tHE tiDE cHAsER: June 2013

Friday, June 28, 2013

Mud Lobsters & Mud Shrimps (Phylum Arthropoda: Infraorder Gebiidea) of Singapore

Gebiideans (phylum Arthropoda, subphylum Crustacea, class Malacostraca, order Decapoda, suborder Pleocyemata, infraorder Gebiidea) are typically burrowing crustaceans with elongate and somewhat flattened abdomens. They are usually found in soft-bottoms of intertidal or subtidal areas. Members of this infraorder that have heavily calcified exoskeletons with spines and tubercles are commonly referred to as mud lobsters, while the more delicate members are usually referred to as mud shrimps.

Mud Lobsters & Mud Shrimps (Infraorder Gebiidea

All gebiideans have strong claws for burrowing, and many species build complex branching burrows in the ground. They mostly feed on decaying organic materials (or detritus), bacteria and other organic matter in the substrate.

Some species may appear similar to the coral ghost shrimps of the infraorder Axiidea, but can be distinguished from the latter by having pincers on the first pair of legs, and very reduced or no pincers on the second pair, instead of having well developed pincers on the first two pairs of legs.

Gebiideans are decapods, and like other members of the order Decapoda, they have five pairs of legs ("deca" means "ten", while "poda" means "feet"). Their body comprises three main parts - a head with five segments, a thorax with eight segments, and an abdomen with six segments. The head is fused with the thorax to form a cephalothorax. The abdomen ends off with a tail-like structure called a telson, and a flattened tail fan is present at the tip.

They have separate sexes, and the females carry the eggs until they are ready to hatch.

In Singapore, I have seen mud lobsters of the family Thalassinidae and mud shrimps of the family Upogebiidae.

A) Mud Lobsters (Family Thalassinidae)

Mud lobsters (family Thalassinidae) are lobster-like crustaceans that live in underground burrows in coastal areas.

Kelanang Mud Lobster (Thalassina kelanang)

Many are found in mangroves, though some also build their burrows along tidal rivers or other coastal habitats on upper shores with soft substrates. Some of the burrows can be very complex with numerous tunnels. As the mud lobster digs into the substrate, the excavated soil is deposited on the surface, and eventually pile up into a mound which can be over a metre tall, appearing much like a miniature volcano.

The mud lobster mound is a very important component in the mangrove ecosystem. The complex burrow systems provide shelter for various other animal species, such as ants, snakes, crabs, lizards etc. Plants also grow on the mound, as the soil that made up the mound are full of nutrients - the mud lobsters thus help to bring nutrient-rich soil from underground to the surface. In addition, the taller mounds are not covered in sea water during high tide. As such, local ecologists often refer to mud lobster mounds as "mud lobster condominium" - they are like "apartments" built by the mud lobsters, but used by many other species.

Mud lobsters are sometimes consumed in the region, and in some countries in the region they are consumed as a remedy for asthma.

Six species of mud lobsters are recorded from Singapore, and so far I have only photographed two of them.

The Scorpion Mud Lobster (Thalassina anomala) is lobster-like, reddish in colour with an elongate abdomen. It is usually found in muddy substrates, and appear to prefer areas with more vegetation. It can get to about 30cm long.

The Kelanang Mud Lobster (Thalassina kelanang) is very similar in appearance to the previous species. It is more commonly found in sandy substrates, and appear to prefer more open areas. The biggest I have seen is about 20cm long.

On the field it can be tentatively distinguished from the previous species by the row of 13-20 blunt spines on the upper edges of its claw, and also by the differences in the markings on the head and the first segment of the abdomen.

In the above picture, the left two images are those of Thalassina kelanang, while the ones on the right are those of Thalassina anomala. Note the differences in the lengths of the ridges on top of the head, and also the aspect ratio of and the markings on the first segment of the abdomen.

B) Mud Shrimps (Family Upogebiidae)

Mud shrimps (family Upogebiidae) appear like small mud lobsters, except that the tail is often broadly fan-shaped. They burrow into the substrates in intertidal areas, and some species even bore into corals. They generally do not build mounds like the ones built by mud lobsters though. They are sometimes confused with the coral ghost shrimps of the infraorder Axiidea, but can be distinguished from the latter by having pincers on the first pair of legs, and very reduced or no pincers on the second pair, instead of having well developed pincers on the first two pairs of legs.

The above picture features an unidentified mud shrimp. It is about 8cm long.

References

Burnie, D. 2001. Animal. London: Dorling Kindersley. 624 pp.
De Grave, S., N. D. Pentcheff , S. T. Ahyong, T.-Y. Chan, K. A. Crandall, P. C. Dworschak, D. L. Felder, R. M. Feldmann, C. H. J. M. Fransen, L. Y. D. Goulding, R. Lemaitre, M. E. Y. Low, J. W. Martin, P. K. L. Ng, C. E. Schweitzer, S. H. Tan, D. Tshudy & R. Wetzer. 2009. A classification of living and fossil genera of decapod crustaceans. The Raffles Bulletin of Zoology, supplement 21, pp. 1-109.
Debelius, H. 1999. Crustacea - Guide of the world. IKAN, Frankfurt. 321pp.
Dworschak, P. C., D. L. Felder & C. C. Tudge. 2012. Infraorders Axiidea de Saint Laurent, 1979 and Gebiidea de Saint Laurent, 1979 (formerly known collectively as Thalassinidea). In: Schram, F.R., J.C. von Vaupel Klein, M. Charmantier-Daures, and J. Forest (eds.) Treatise on zoology - Anatomy, taxonomy, biology - The crustacea, decapoda, Volume 9 Part B Decapoda: Astacidea P.P. (Enoplometopoidea, Nephropoidea), Glypheidea, Axiidea, Gebiidea, and Anomura. Vol. 9B. Pp. 109–219
Moh, H. H. & Chong, V. C. 2009. A new species of Thalassina (Crustacea: Decapoda: Thalassinidea) from Malaysia. Raffles Bulletin of Zoology, 57, 465-473.
Nguyen, N.-H. & M. de Saint Laurent. 2009. The genus Thalassina Latreille, 1806 (Crustacea: Thalassinidea: Thalassinidae). The Ruffles Bulletin of Zoology Suppl. 20: 121-158.
World Register of Marine Species. 2012. Retrieved Jun 10, 2013, from http://www.marinespecies.org.

Wednesday, June 12, 2013

Arthropods (Phylum Arthropoda) of Singapore

Arthropods (phylum Arthropoda) form the largest single phylum in the animal kingdom, with more than a million species that has been described, making up more than 80 percent of all known animal species.

They are bilaterally symmetrical with segmented bodies and jointed (or segmented) limbs. In fact, "arthropoda" means "jointed legs" in ancient Greek.

Their body is enclosed in an external skeleton (or exoskeleton) composed largely of a tough material called chitin. This exoskeleton functions like a protective but rigid armour, and hence as the arthropod develops through it life stages and changes in size and/or shape, it will need to moult, i.e. discard the old skeleton and grow a new one.

Most species reproduce by sexual reproduction, though some species are known to reproduce by parthenogenesis (the embryos develop without fertilisation). Some species are hermaphroditic (possessing both male and female reproductive parts), but most have separate sexes and remain the same sex throughout their lives. For those that reproduce sexually, fertilisation is usually internal. The male either inserts its reproductive structure directly into the female's reproductive parts, or deposits a sperm package to be picked up by the female. Some aquatic species may perform external fertilisation, with the female laying the eggs to be fertilised subsequently by the male.

The extant groups of arthropods that can be seen in Singapore are as follow:

A) Subphylum Myriapoda

Myriapods (subphylum Myriapoda) are typically elongate arthropods which possess numerous pairs of legs ("myriapoda" means "10,000 legs" in ancient Greek), a trunk with many segments, and a head with one pair each of mandibles and antennae at the front end. The cuticle (i.e. outer covering) of myriapods is not waterproof, and hence they are largely terrestrial. Most species are also nocturnal to avoid water loss, and are most readily found in damp habitats such as the leaf litter or underground. They can breathe by taking in air through openings in the cuticle.

Myriapods are generally harmless to human, except for some venomous species. The bites may be painful, but are rarely fatal unless the victim is allergic to the venom.

The myriapods that I have photographed in Singapore include:

1. Millipedes (Class Diplopoda)

Millipedes (class Diplopoda) are easily recognised by their long segmented body with two pairs of legs on most segments, except for the first few and last segments. The name means "a thousand legs", and the ones seen in Singapore can have more than 300 legs. Most species feed on decaying organic matter or fungi. They are not venomous, and protect themselves either by secreting toxic or distasteful chemicals, or roll up to protect their softer underparts, exposing only the tougher upperparts. To breed, the males usually twist their bodies around the females to transfer the sperm, and the females will lay the eggs inside a nest in the soil.

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2. Centipedes (Class Chilopoda)

Centipedes (class Chilopoda) are myriapods with an elongate and flattened body made up of at least 16 segments. Each segment has one pair of legs. Interestingly, they always have an odd number of pairs of legs, with the last pair longer than the rest, and the first pair modified into venomous fangs (or forcipules). They use their venomous fangs to hunt smaller animals. While the venom is generally not fatal to human, been bitten by the bigger species can be very painful. To breed, the males usually drop the sperm on the ground that the females pick up. The eggs may be laid singly or brooded in batches underground.

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3. Symphylans (Class Symphyla)

Symphylans (class Symphyla) are small, whitish myriapods with a soft body made up of 15 segments, including a head with a pair of long antennae and three pairs of mouthparts, and a trunk made up of 14 segments. A pair of tail-like structures (or spinnerets) extends from the last segment. They have no eyes, and are often found in the soil or in the leaf litter, feeding on plant materials. Some species are perceived as garden pest, as they feed on living plant matter, such as the roots. To breed, the males deposit sperm packages that are picked up by the females. The above photo features an unidentified symphylan found among the leaf litter.

B) Subphylum Chelicerata

Chelicerates (subphylum Chelicerata) are arthropods which possess two main body parts - the cephalothorax (head and thorax fused together) and the abdomen, though for some the division between the two parts may not be visible. They have specialised appendages called chelicerae that are used mostly for feeding, positioned before the mouth. The marine species breathe with gills, while terrestrial species may have either book lungs (composed of stacks of alternating air pockets and hemolymph-filled tissues) or tracheae (a system of tubes).

Most chelicerates are harmless to human, including many of the venomous species. The bites may be painful, but are rarely fatal unless the victim is allergic to the venom. The venoms of the species found in Singapore are not known to be lethal, and no one in Singapore is known to have died from chelicerate bites/stings.

Here are some examples of the many chelicerate groups that can be seen in Singapore.

1. Horseshoe Crabs (Class Merostomata)

Horseshoe Crabs (order Xiphosura, family Limulidae) are the only extant members of the class Merostomata. They can be recognised by the horseshoe-shaped carapace, and a long, spine-like tail. On the underside, there are six pairs of appendages. The mouth part is located in the middle. During the breeding season, the male will be seen riding on the larger female's back. Fertilisation is external though - the female will lay the eggs, and the male will then deposit the sperm on them.

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2. Arachnids (Class Arachnida)

Arachnids (class Arachnida) can be distinguished from other chelicerates by having six pairs of appendages on the underside of the cephalothorax - a pair of fang-like or pincer-like chelicarae, a pair of leg-like or pincer-like pedipalps, and four pairs of walking legs. Most are predators, though there are also several species that scavenge and some others that parasitise other animals. In most species, the males will pass a sperm package to the female to fertilise the eggs. Many arachnids are observed to provide parental care by guarding the eggs or even the newly hatched.

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3. Sea Spiders (Class Pycnogonida)

Sea spiders (class Pycnogonida) are not true spiders, but a group of marine arthropods with mostly four pairs of long walking legs (some species may have five or six pairs), hence resembling the latter superficially. They have a head with two pairs of eyes, a proboscis used for feeding, and most species have two clawed appendages (or chelifers) and a pair of pedipalps. Fused to the head is a cylindrical thorax (usually with three segments) where the legs are attached to, and at the end is a short abdomen without any segments. Sea spiders lack respiratory organs and gases are absorbed/released by diffusion. They usually feed on sessile marine invertebrates. There is much dispute over whether the sea spiders should be a chelicerate or a separate lineage of their own.

C) Subphylum Hexapoda

Hexapods (subphylum Hexapoda) are arthropods with six walking legs. Their body is divided into three main parts - the head, the thorax and the abdomen. The legs are attached to the thorax. Most species have a pair of antennae on their head. They usually reproduce by sexual reproduction, though some species are known to reproduce by parthenogenesis.

Here are the hexapod groups that can be seen in Singapore.

1. Insects (Class Insecta)

Insects (class Insecta) form the largest group of animals on Earth, with more than a million species being described. Like other hexapods, they have three pairs of legs, and the body is made up of a head, thorax and abdomen. They are distinguished from other hexapods by their external mouthparts. Many insects also have wings, and they are the only group of arthropods capable of powered flight. They mostly reproduce by sexual reproduction, with the male either inserting its reproductive structure directly into the female's reproductive parts, or depositing a sperm package to be picked up by the female.

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2. Non-insect Hexapods (Class Entognatha)

Non-insect hexapods (class Entognatha) include the springtails (order Collembola), Diplurans (order Diplura) and Proturans (order Protura). They are distinguished from the insects by having their mouthparts enclosed within a pouch on the underside of their head. They also lack wings, and some species may even lack eyes and antennae. The above photo features a springtails about 3mm long. Most springtails have a tail-like structure folded beneath the body which snaps against the ground to fling the animal into the air when threatened. They mostly feed on decaying organic materials, though some are carnivorous. They usually reproduce sexually, with the males depositing sperm packages to be picked up by the females. The eggs are laid in the soil or leaf litter, and upon hatching, develop quickly into adults, and continue to moult after reaching adulthood.

C) Subphylum Crustacea

Crustaceans (subphylum Crustacea) are arthropods with two pairs of antennae, compound eyes on stalks, and an exoskeleton that is usually reinforced with calcium carbonate. For most species, the head and the thorax are covered with a shield-like structure called a carapace, and the abdomen ends off with a tail-like structure called a telson. They often have a variety of appendages for feeding, walking, swimming, mating and sensory purposes.

Most crustaceans reproduce sexually, though some are known to reproduce by parthenogenesis (the embryos develop without fertilisation). A number of species are hermaphroditic (possessing both male and female reproductive parts), and some may change sex during the course of their lives. Some aquatic species broadcast their fertilised eggs into the water column, while others may carry the eggs until they are ready to hatch, or attach the eggs to rocks, plants or other objects. For aquatic species, the eggs will hatch into larvae that usually appear very different from the adults. For terrestrial species like the woodlouse, the young may appear similar to the adult but has fewer legs.

A wide variety of crustaceans can be found in Singapore, but only a few groups are readily seen and easy enough to distinguish from others. Hence, I will only include the few crustacean groups that I have photographed in Singapore here.

1. Malacostracans (Class Malacostraca)

Malacostracans (class Malacostraca) have bodies made up of three main parts - a head with five segments, a thorax with eight segments, and an abdomen with 6 segments. The head may be fused with the thorax to form a cephalothorax. They often have a tough exoskeleton strengthened with calcium carbonate, and the carapace (if present) covers the gills but not the abdomen. Most species have stalked eyes. They have prominent antennae, and up to three pairs of appendages may be modified into mouthparts for manipulating food. The tail usually has a flattened tail fan. Most malacostracans have separate sexes, though a number of species are hermaphroditic (possessing both male and female reproductive parts).

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2. Barnacles & Allies (Class Maxillopoda)

$Barnacles (infraclass Cirripedia)$
Barnacles (infraclass Cirripedia) and several tiny crustaceans such copepods and fishlice made up the class Maxillopoda, of which the barnacles are the most readily seen on our seashores. Most barnacles appear like miniature volcanoes or limpets attached to rocks and other hard structures. During their larva stage, however, they resemble small shrimps with a segmented body and jointed legs. The larva eventually finds a suitable substrate and attaches itself permanently to it with a cement-like substance it produces, and secrete a conical shell around it. There is a hole at the top of the shell, which allows the animal to extend its hairy appendages to filter plankton from the water during high tide. During low tide, the animal will hide in the shell and block the opening with a trapdoor-like operculum. Not all barnacles have this volcano-like appearance, and some species are stalked - appearing somewhat like a germinating seed. Some barnacles are parasitic, and have no legs and shells.

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References

Bartlett, T. & J. VanDyk. 2003. BugGuide. Retrieved May 24, 2013, http://bugguide.net.
Burnie, D. 2001. Animal. London: Dorling Kindersley. 624 pp.
Decker, P. & T. Tertilt. 2012. First records of two introduced millipedes Anoplodesmus saussurii and Chondromorpha xanthotricha (Diplopoda: Polydesmida: Paradoxosomatidae) in Singapore. Nature in Singapore, 5: 141–149.
Ecological Research & Development Group. The Horseshoe Crab. Retrieved May 24, 2013, http://www.horseshoecrab.org.
McGavin, G. 2000. Dorling Kindersley Handbooks: Insects, spiders and other terrestrial arthropods. London: Dorling Kindersley. 255 pp.
Ng, P. K .L., R.T. Corlett & H.T.W. Tan (eds.). 2011. Singapore Biodiversity: An Encyclopedia of the Natural Environment and Sustainable Development. Singapore: Editions Didier Millet. 552 pp.

Prawns (Phylum Arthropoda: Suborder Dendrobranchiata) of Singapore

Prawns (phylum Arthropoda, subphylum Crustacea, class Malacostraca, order Decapoda, suborder Dendrobranchiata) can be distinguished from other similar looking decapods by having gills that are branch-like, instead of leaf-like. They also do not hold their eggs until they hatch, but release the fertilised eggs directly into the water column. While they are commonly called prawns in the region, they may be referred to as shrimps (not to be confused with the caridean shrimps) in other countries. Unlike the penaeid prawns, caridean shrimps does not have pincers at the tip of the third pair of walking legs, and also, the "shell" of the second segment of the abdomen is enlarged, overlapping and covering part of the first segment and the third segment.

Their body typically comprises three main parts - a head with five segments, a thorax with eight segments, and an abdomen with six segments. They have two pairs of antennae on their head - the first pair is usually very reduced, while the second pair can be much longer than the body. They have a pair of compound eyes on stalks. As with most other decapods, they have five pairs of walking legs or pereiopods ("deca" means "ten", while "poda" means "feet") attached to the thorax. The first three pairs of legs have small pincers at the tip to assist with feeding. The abdomen is elongate, bearing five pairs of swimming appendages (or pleopods) and ends off with a tail fan comprising a pointed, tail-like structure (or telson) in the middle and a pair of flattened appendages (or uropods) by the sides. The pleopods are used for for swimming, while the uropods are used for steering while swimming.

Prawns are very important in commercial fishing, as many species are consumed in the region.

A) Sergestid Prawns (Family Sergestidae)

The sergestid prawns (family Sergestidae) seen in Singapore usually swarm in the hundreds and thousands, feeding on algae and plankton. Some species are often collected to make prawn paste (belachan), and hence locally they are commonly called Belachan Prawns. Generally, their carapace has poorly developed crests and grooves, and the rostrum (pointed, "nose-like" structure on the forehead) is shorter than the eye-stalk. The first pair of walking legs may or may not have pincers, but the second and third pairs definitely come with mall pincers. Meanwhile, the fourth and fifth pairs of walking legs are shorter than the rest or even absent.

The Belachan Prawns (Acetes spp.) can be differentiated from other sergestid prawns by the lacking of the fourth and fifth pairs of walking legs altogether. They occur in huge swarms, and sometimes several thousands can be seen in shallow waters or in tidal pools. While they are quite small sized, being not more than 4cm long, they are collected by the locals to make into prawn paste, or dried under the sun and cooked with other ingredients. Since they occur in huge numbers, they are an important source of protein for fishing villagers.

The above picture features a small part of a huge swarm of Belachan Prawns in a tidal pool.

B) Penaeid Prawns (Family Penaeidae)

Penaeid prawns (family Penaeidae) are typically much larger than those of the previous family. They have a very well-developed and toothed rostrum (pointed, "nose-like" structure on the forehead) which usually extends beyond the eyes. The fourth and fifth pairs of walking legs are very well developed, and are about the same size as the others. Penaeid prawns are very important commercially, being widely consumed in the region, and some species are thus farmed in prawn ponds.

The Western King Prawn (Melicertus latisulcatus) is very commonly seen in Singapore, especially in sandy lagoons where they are often seen scampering around or partially buried under the sand, revealing only the eyes. It can be recognised by the bluish tail, and obvious black spots on the sides of its abdomen. Those without the black spots are deemed to be a different species. This prawn can get to about 20cm long.

The Longarm Prawn (Heteropenaeus longimanus) is usually seen in coral reefs, and hence rarely seen in the intertidal area. It does not get longer than 10cm, and is less often consumed due to the smaller size compared to the other prawn species.

This Penaeus sp. with red appendages is often seen in seagrass meadows. The biggest Penaeus species can get to over 30cm long, though I am not sure the exact species of the one featured in the above photo and hence cannot provide the length. Some Penaeus species are reared in prawn ponds in the region, and the creation of these ponds has resulted in the destruction of many mangrove forests.

This Penaeus sp. which is all greenish in colour is a juvenile. The colour helps it to blend into the surrounding seaweed and seagass.

This unidentified penaeid prawn was seen once swimming near the surface of the water. It is a rather big prawn, about 20cm long.

References

De Grave, S., N. D. Pentcheff , S. T. Ahyong, T.-Y. Chan, K. A. Crandall, P. C. Dworschak, D. L. Felder, R. M. Feldmann, C. H. J. M. Fransen, L. Y. D. Goulding, R. Lemaitre, M. E. Y. Low, J. W. Martin, P. K. L. Ng, C. E. Schweitzer, S. H. Tan, D. Tshudy & R. Wetzer. 2009. A classification of living and fossil genera of decapod crustaceans. The Raffles Bulletin of Zoology, supplement 21, pp. 1-109.
Carpenter, K. E. & V. H. Niem (eds), 1998-2001. FAO species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. Volumes 1 to 6. FAO, Rome. pp. 1-4218.
Debelius, H. 1999. Crustacea - Guide of the world. IKAN, Frankfurt. 321pp.
Ng, P. K. L., S. S. L. Lim, L. K. Wang & L. W. H. Tan. 2007. Private lives: An exposé of Singapore's shores. The Raffles Museum of Biodiversity Research, Department of Biological Sciences, National University of Singapore. 212 pp.
Ng, P. K .L., R.T. Corlett & H.T.W. Tan (eds.). 2011. Singapore biodiversity: An encyclopedia of the natural environment and sustainable development. Singapore: Editions Didier Millet. 552 pp.
Tan, L. W. H. & P. K. L. Ng. 1988. A guide to seashore life. Singapore Science Centre. Singapore. 160 pp.
World Register of Marine Species. 2012. Retrieved Jun 10, 2013, from http://www.marinespecies.org.

Isopods (Phylum Arthropoda: Order Isopoda) of Singapore

Isopods (phylum Arthropoda, subphylum Crustacea, class Malacostraca, order Isopoda) probably has the most diverse appearance among the crustaceans, ranging from flattened and bug-like, to longish and worm-like. Most of the ones seen on land and in shallow water have the former appearance though.

They lack an obvious carapace, or have a very reduced one. With regards to their diet, some species are scavengers or detrital feeders, some are known to feed on algae, and some parasitise other animals, but generally, little is known about the diet of most isopods.

Here are some of the isopods that I have photographed in Singapore:

The Woodlouse (Suborder Oniscidea) is commonly seen in damp areas in parks and forests, such as in the leaf litter or under logs. They have the typical flattened appearance and clearly segmented bodies. Like most terrestrial crustaceans, they have brood pouches on the underside of their bodies to keep the fertilised eggs until they hatch. Woodlice seen in Singapore are seldom more than 1cm long, and most are just a few mm long.

Some woodlice may roll into a ball when disturb, and are often called pillbugs. Generally, woodlice play the important role as decomposers in terrestrial ecosystems, though some species may feed on shoots and young fruits and hence are sometimes considered minor pest in gardens.

The Sea Slater (Ligia sp.) is an isopod commonly seen on seashores, especially rocky areas, moving quickly around and scampering away in a split second when disturbed. They are scavengers, and thus help to keep the shoreline clean as they feed on any dead animal materials on the shore. Like the woodlice, female Sea Slaters also have brood pouches to keep the fertilised eggs until they hatch. Sea Slaters in Singapore are mostly less than 2cm long (head to end of abdomen).

Bopyrid Isopods (family Bopyridae) are parasitic isopods which live in the gill chambers of bigger crustaceans, causing a lump-like swelling. The picture above features a shrimp with a parasitic isopod on one side of its gill chamber, resulting in a big, tumour-like lump. These isopods attached themselves to the gills with strong, hook-like appendages, feeding on the blood from the gills.

References

Bartlett, T. & J. VanDyk. 2003. BugGuide. Retrieved May 24, 2013, http://bugguide.net.
Burnie, D. 2001. Animal. London: Dorling Kindersley. 624 pp.
Debelius, H. 1999. Crustacea - Guide of the world. IKAN, Frankfurt. 321pp.
McGavin, G. 2000. Dorling Kindersley Handbooks: Insects, spiders and other terrestrial arthropods. London: Dorling Kindersley. 255 pp.
Ng, P. K. L., S. S. L. Lim, L. K. Wang & L. W. H. Tan. 2007. Private lives: An exposé of Singapore's shores. The Raffles Museum of Biodiversity Research, Department of Biological Sciences, National University of Singapore. 212 pp.
Ng, P. K .L., R.T. Corlett & H.T.W. Tan (eds.). 2011. Singapore biodiversity: An encyclopedia of the natural environment and sustainable development. Singapore: Editions Didier Millet. 552 pp.
World Register of Marine Species. 2012. Retrieved Jun 10, 2013, from http://www.marinespecies.org.

Amphipods (Phylum Arthropoda: Order Amphipoda) of Singapore

Amphipods (phylum Arthropoda, subphylum Crustacea, class Malacostraca, order Amphipoda) are crustaceans that lack a carapace and often appear laterally compressed. They are very diverse but often overlooked due to the small sizes of terrestrial and intertidal species. The deep water species can get to about 30cm long though.

Unlike many crustaceans, their eyes are unstalked, and in front of the eyes are two pairs of antennae. They typically have seven pairs of walking legs (pereopods), with the first two pairs modified to assist in feeding. They have an additional three pairs of swimming legs (pleopods) at the back, and three more appendages (uropods) to help with locomotion. In some groups, these appendages may be very much reduced or absent.

Some amphipods scavenge, while others may feed on decaying organic particles (detritus) on the substrate or filter plankton. The females carry their eggs in a brood pouch on the underside, and the eggs hatch directly into miniature adults.

As amphipods are very small and hard to photograph, I only have photos of a few local examples.

The Landhopper (family Talitridae) is commonly seen among the leaf litter or in moist areas in forests or gardens. They got their common name from their habit of flexing their abdomens and flicking themselves into the air when disturbed. It is usually just about 5mm long or shorter.

The Sandhopper (family Talitridae) is of the same family as the previous group, but is found on the beach instead. Like their relatives, they are often "hop" away when disturbed. Sandhoppers are mostly scavengers and detrital feeders, and are often seen foraging on vegetative materials washed up by the currents. The biggest that I have seen is about 5mm long.

The Skeleton Shrimp (family Caprellidae) is a rather "atypical" amphipod since it lacks the many legs found in most species. They usually appear elongated, having a thin and long thorax with a pair of large claws near the front end, appearing somewhat like a crunching skeleton, and hence the common name. They do not swim, but instead cling to seaweed or other sessile organisms and catch food particles that drift by. The ones in Singapore are mostly just a few mm long.

References

Bartlett, T. & J. VanDyk. 2003. BugGuide. Retrieved May 24, 2013, http://bugguide.net.
Burnie, D. 2001. Animal. London: Dorling Kindersley. 624 pp.
Debelius, H. 1999. Crustacea - Guide of the world. IKAN, Frankfurt. 321pp.
McGavin, G. 2000. Dorling Kindersley Handbooks: Insects, spiders and other terrestrial arthropods. London: Dorling Kindersley. 255 pp.
Ng, P. K. L., S. S. L. Lim, L. K. Wang & L. W. H. Tan. 2007. Private lives: An exposé of Singapore's shores. The Raffles Museum of Biodiversity Research, Department of Biological Sciences, National University of Singapore. 212 pp.
World Register of Marine Species. 2012. Retrieved Jun 10, 2013, from http://www.marinespecies.org.

Mantis Shrimps (Phylum Arthropoda: Order Stomatopoda) of Singapore

Mantis shrimps (phylum Arthropoda, subphylum Crustacea, class Malacostraca, order Stomatopoda) are crustaceans with a pair of enlarged appendages that they carry folded beneath the head, somewhat similar to the forelimbs of a praying mantis. The way they strike the prey is different though - the mantis strikes its prey overhand, while the mantis shrimp strikes its prey underhand, thus hitting the fish or other smaller crustaceans from below where they are more vulnerable. The strike is very fast, taking as little as three milliseconds, making it hard to avoid.

As with other crustaceans from the class Malacostraca, their body typically comprises three main parts - a head with five segments, a thorax with eight segments, and an abdomen with six segments. The head is fused with the thorax to form a cephalothorax. They have a tough exoskeleton strengthened with calcium carbonate, and the carapace covers the gills but not the abdomen. The abdomen is elongate, and ends off with a tail-like structure called a telson, and and a flattened tail fan is usually present at the tip.

Mantis shrimps can generally be divided into two main groups - the smashers and the spearers - based on the appearance of their striking appendages and how they are used. The smashers have a heavily calcified knob at the tip of the appendages, which they use to punch their prey, including crabs and snails, breaking theirs shells before they are consumed. The punch of these smashers is so strong, that they cannot be kept in normal fish tanks because they can easily break the glass. There are also many stories of mantis shrimps being unknowingly introduced aquariums, killing the other inhabitants and smashing the corals and other sessile animals into pieces.

The spearers lack the knob at the tip of the hunting appendages, but instead the last segment is armed with numerous sharp spines. They often prey on fishes and other soft-bodied animals, striking them at high speed and impaling them on the sharp spines.

Mantis shrimps have a pair of compound eyes, and each compound eye has been modified to be able to accurately judge distance (unlike human and many animals, which need both eyes to do so). This allows the animal to effectively hunt even in confined spaces.

Many spearers are known to ambush prey near their burrows or come out to hunt actively at night. As a result, their eyes have developed such that they can see well in the dark, and only possess single visual pigment which does not allow them to distinguish colours. This basically means that they will not be distracted by the different colours, and have an easier task of watching out for movements of prey and predators. Smashers, on the other hand, hunt in the day, and studies have shown that many of them have at least 10 visual pigments and several colour filters. It is impossible for humans to imagine the colourful world viewed by a smasher shrimp, when we only have three visual pigments.

Mantis shrimps have separate sexes, and reproduce sexually. Depending on the species, the female may lay the eggs in a burrow, or carry them with her.

Here are the mantis shrimps that I have photographed in Singapore so far:

A) Smashers

The smashers I have seen in Singapore are from the family Gonodactylidae, and can be easily recognised by the heavily calcified knob at the tip of their hunting appendages.

This Green Smasher (Gonodactylus sp.) is sometimes found under rocks or foraging among the seagrass. The ones I have seen are usually not more than 7-8cm long.

B) Spearers

The spearers I have photographed in Singapore are from the family Squillidae, though members of the families Lysiosquillidae and Harpiosquillidae have also been recorded. They are often collected by commercial trawls as bycatch, but the numbers are significant enough for a steady supply to some of the regional markets.

Squillids can be distinguished lysiosquillids by having an obvious "ridge line" in the middle of its tail, and from harpiosquillids by the lack of an angular corner on the sides of the carapace.

The Spotted Squillid Mantis Shrimp (Chloridopsis scorpio) is easily recognised by having a black patch on the forward-curving spine at its collar. It is usually seen among the seagrass on sandy bottoms, and can grow to about 10cm.

This Oratosquilla sp. can be recognised by having an obvious and unbroken Y-shaped ridge on the back of its carapace in the middle (see earlier picture on squillid mantis shrimps for a close-up of the carapace). It is a rather big mantis shrimp, and the biggest I have seen is probably about 15cm long.

This unknown squillid mantis shrimp with a vague "ridge-line" in the middle of its carapace is seldom seen, and I have not been able to identify it yet. It is only about 10cm long.

References

Burnie, D. 2001. Animal. London: Dorling Kindersley. 624 pp.
Carpenter, K. E. & V. H. Niem (eds), 1998-2001. FAO species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. Volumes 1 to 6. FAO, Rome. pp. 1-4218.
Debelius, H. 1999. Crustacea - Guide of the world. IKAN, Frankfurt. 321pp.
McGavin, G. 2000. Dorling Kindersley Handbooks: Insects, spiders and other terrestrial arthropods. London: Dorling Kindersley. 255 pp.
Ng, P. K. L., S. S. L. Lim, L. K. Wang & L. W. H. Tan. 2007. Private lives: An exposé of Singapore's shores. The Raffles Museum of Biodiversity Research, Department of Biological Sciences, National University of Singapore. 212 pp.
Ng, P. K .L., R.T. Corlett & H.T.W. Tan (eds.). 2011. Singapore biodiversity: An encyclopedia of the natural environment and sustainable development. Singapore: Editions Didier Millet. 552 pp.
World Register of Marine Species. 2012. Retrieved Jun 10, 2013, from http://www.marinespecies.org.

Barnacles (Phylum Arthropoda: Infraclass Cirripedia) of Singapore

Barnacles (phylum Arthropoda, subphylum Crustacea, class Maxillopoda, infraclass Cirripedia) are most easily seen on the upper shores, where they appear like miniature volcanoes attached to rocks and other hard structures.

They may resemble limpets (which are molluscs), but they are crustaceans, most obvious in their larva stage when they superficially resemble small shrimps with a segmented body and jointed legs. The larva eventually finds a suitable substrate and attaches itself permanently to it with a cement-like substance it produces, and secretes a conical shell around it. There is a hole at the top of the shell (hence appearing like a miniature volcano), which allows the animal to extend its hairy appendages to filter plankton from the water during high tide. During low tide, the animal will hide in the shell and block the opening with a trapdoor-like operculum.

Not all barnacles have this volcano-like appearance, and some species are stalked - appearing somewhat like a germinating seed. These are often called goose barnacles as some species resemble the head and neck of a goose (with some imagination), and may attach to rocks or flotsam.

Some barnacles are parasitic, and are found attached to the gills or other internal parts of other animals. These crustaceans have lost their legs and shells, and feed on the tissues of the hosts. Some parasitic barnacles may damage the reproductive systems of their hosts.

Most barnacles are hermaphroditic, and being sessile makes sexual reproduction a challenge. These barnacles have thus developed very long penises which extend out of their shells to fertilise other neighbouring barnacles. It is believed that barnacles probably have the longest penises relatively to the body size in the animal kingdom. For some species that have separate sexes, a tiny male often lives within the shell of a much larger female to make fertilisation easier. The fertilised eggs will hatch into planktonic larvae.

As barnacles tend to stick to any hard surfaces, including marine vessels and port structures, they are often viewed as a problem in the maritime industry (readers of the comic series Tin Tin will remember Captain Haddock cursing, "Billions of bilious blue blistering barnacles!"). Barnacles that grow on marine vessels add weight and slow down them down, while those that grow on maritime equipment may cause them to malfunction, or make them difficult to handle as the edges of these barnacles can be quite sharp, causing cuts and blisters. The research on reducing barnacle growth is hence a huge industry itself.

Some of the bigger barnacle species are consumed by human.

Several groups/species of barnacles can be found in Singapore, though the ones I have photographed so far are all from the superorder Thoracica. Members of this order may be sessile (stuck to hard surfaces in conical shells) or stalked.

A) Order Sessilia

This order comprises the sessile barnacles which secrete a conical shell permanently stuck to a hard surface. They normally feed by actively waving their "hairy" appendages during high tide to filter food particles from the water column.

Volcano Barnacles (Tetraclita sp.) form hard, conical shells. The thick wall of the shell has numerous holes and gaps internally (much like a sponge!), holding many pockets of air for heat insulation. The width of the barnacle can get to about 3cm. It is often found on huge rocks, and unlike most of the other species below, does not usually occur in huge clusters.

Star Barnacles (Euraphia sp.) has a star-like appearance, and are usually not more than 1cm wide. They often occur high up on the shore, forming huge clusters on areas above the other barnacles.

Acorn Barnacles (Balanus sp.) are possibly the most commonly seen barnacles. They often form a continuous layer on rocks and other hard structures on the high shore.

Acorn Barnacles can also be found growing on the shells of other living things, such as the ones above growing on the shell of a crab hiding under the sand.

Here is another example of Acorn Barnacles growing on the exoskeleton of a crab.

Coral Barnalces (Pyrgomatidae, Megabalanidae or Balanidae)

Many species of barnacles from the family Pyrgomatidae, Megabalanidae and Balanidae are known to embed themselves in corals. They are commonly called Coral Barnacles, and can be differentiated by the number of calcareous shell plates they posses. These plates, however, can only be examined if the specimen is removed from the coral host, and hence identification is usually hard in the field. The unidentified species featured in the above picture has a bluish coloration, and the specimens are embedded in a coral of the family Faviidae.

This unidentified species appeared to have gained some control over the hard coral's calcification ability, as the corallites which they are embedded in are much larger than the unaffected surrounding ones. The host coral appears to be of the family Faviidae.

B) Order Pedunculata

This order comprises barnacles that are attached to surfaces via a flexible stalk. Unlike the previous group, they are dependent on water movement to filter food particles, and generally do not actively move their "hairy" appendages.

Parasitic Goose Barnacles (Octolasmis sp.)

Commensal Goose Barnacles (Octolasmis sp.) are sometimes found attached to the gills of crustaceans. They do not cause much harm to the host, but are just hitching a ride and benefiting from the water currents created by the gills, which bring plankton and other suspended food particles. However, when the crustacean hosts moult, these barnacles will be discarded with the old exoskeleton.

References

Achituv, Y. & N. Simon-Blecher. 2006. Pyrgopsella (Cirripedia: Balanomorpha: Pyrgomatidae) is not a sponge-inhabiting barnacle. Zootaxa (1319): 29-41.
Burnie, D. 2001. Animal. London: Dorling Kindersley. 624 pp.
Debelius, H. 1999. Crustacea - Guide of the world. IKAN, Frankfurt. 321pp.
Ng, P. K .L., R.T. Corlett & H.T.W. Tan (eds.). 2011. Singapore Biodiversity: An Encyclopedia of the Natural Environment and Sustainable Development. Singapore: Editions Didier Millet. 552 pp.
Ng, P. K. L., S. S. L. Lim, L. K. Wang & L. W. H. Tan. 2007. Private lives: An exposé of Singapore's shores. The Raffles Museum of Biodiversity Research, Department of Biological Sciences, National University of Singapore. 212 pp.
Simon-Blecher, N., D. Huchon & Y. Achituv. 2007. Phylogeny of coral-inhabiting barnacles Cirripedia; Thoracica; Pyrgomatidae based on 12S, 16S and 18S rDNA analysis. Molecular Phylogenetics and Evolution 44(3): 1333-1341

Insects (Phylum Arthropoda: Class Insecta) of Singapore

Insects (phylum Arthropoda, subphylum Hexapoda, class Insecta) form the largest group of arthropods on Earth, with more than a million species being described. Insecta is also the class with the most number of known animal species - roughly one out of every four known animal species is an insect. In fact, more than half of the known species of livings things on Earth are insects.

As with other arthropods, insects have jointed legs ("arthropoda" means "jointed legs" in ancient Greek), a bilaterally symmetrical body, and an exoskeleton (or external skeleton) composed largely of a tough material called chitin. As they grow, they need to moult, i.e. discard the old skeleton and grow a new one.

They have three pairs of legs, and hence they are placed in the subphylum Hexapoda, which means "six legs". Their body is made up of a head, thorax and abdomen. Insects, however, can be distinguished from other hexapods by their external mouthparts. Many species also have wings, and they are the only group of arthropods capable of powered flight.

While they can be found on land, in the air, underground, or even in the water, all adult insects breathe air through openings in the cuticle called spiracles. The nymph or larvae of some species have gills to breathe in water though. Most insects have two types of eyes - compound eyes which consist of hundreds of light-sensitive units giving them true vision, or simple eyes which mostly can only sense light and darkness.

Most insects reproduce by sexual reproduction, though some species are known to reproduce by parthenogenesis (the embryos develop without fertilisation). Fertilisation is usually internal, with the male either inserting its reproductive structure directly into the female's reproductive parts, or depositing a sperm package to be picked up by the female.

Insects generally begin their lives as an egg, but may subsequently undergo an ametabolous development, an incomplete metamorphosis, or a complete metamorphosis. Ametabolous development occurs in some wingless insects, whereby a nymph with little difference from the adult emerges from the egg, and moults several times to grow bigger into an adult. In an incomplete metamorphosis, the nymph appears similar to the adult but lacks wings and reproductive organs. It gradually moults several times to become an adult (with wings and reproductive parts). In a complete metamorphosis, a larva (usually appear worm-like looking nothing like the adult) emerges from the egg. It will moult several times, and become a pupa within a protective rigid covering or cocoon during the last moult. Eventually, an adult will emerge from the pupa.

As there are many species of insects in Singapore, and I am certainly no expert in this area, I will only attempt to provide an introduction to identifying some of the common insects groups to their order, but will not go into the exact species.

A) Bristletails (Order Archaeognatha)

Bristletails (order Archaeognatha) are primitive, wingless insects with three long tail filaments. They usually appear a humpbacked when viewed from the sides. They have simple mouthparts and feed mostly on algae and plant materials. Bristletails have a pair of large compound eyes that meet at the top of their head, unlike the similar-looking silverfishes which have relatively widely separated eyes or none at all. They can also jump (silverfishes do not jump), and hence they are also sometimes called jumping bristletails.

Bristletails are ametabolous, meaning the nymph does not differ much from the adult, and moults several times to grow bigger into an adult. Unlike most insects, they will continue to moult even after reaching adulthood. To breed, the males will deposit a sperm package for the female to pick up with her genitalia, and the fertilised eggs are usually laid in cracks and crevices.

B) Cockroaches & Termites (Order Blattodea)

Cockroaches and termites (order Blattodea) may appear rather different at first look, but both have chewing mouthparts, sturdy legs, an abdomen with 10 segments for adults, and two pairs of membranous wings when present. The wings are usually folded left over right when at rest. They undergo an incomplete metamorphosis (see introduction at the top) in their life cycle.

The cockroaches (left three photos) generally have flattened, oval-shaped bodies. The head is usually covered by a shield-like plate. The top pair of wings are usually tougher. Some are solitary, while others may live in small family groups. They generally feed on dead or decaying organic matter (including household items made from plant or animal products).

The termites (right-top and right-bottom) have a soft and roundish abdomen. These are eusocial (means true social) animals living in huge colonies with caste systems, with a reproductive caste comprising a pair or more reproductives (kings and queens which can reproduce), a worker caste comprising numerous sterile workers which gather food and maintain the nest, and a soldier caste (only in some colonies) comprising bigger termites with enlarged jaws for protecting the colony. They feed on dead plant material, such as wood and leaf litter.

C) Beetles (Order Coleoptera)

Beetles (order Coleoptera) made up about one-third of the known insect species in the world. They can be easily recognised by the pair hardened forewings (also known as the elytra) which meet along the centre of the body, protecting the folded membranous hindwings underneath. The protective elytra allows the various species of beetles to survive well in a variety of habitats, such as underground or even underwater.

Beetles mostly feed on plant materials, but some species are known to be scavengers or predators. To breed, the male will usually ride on the back of the female. They undergo a complete metamorphosis in their life cycle. The above picture features a few beetles that can be seen in Singapore, including (clockwise from the main picture) a longhorn beetle, a ladybird, a female trilobite beetle (which stays in the larvae form), a firefly, a weevil, a leaf beetle, and a tortoise beetle.

D) Earwigs (Order Dermaptera)

Earwigs (order Dermaptera) got its common name from old wive's tale that they can crawl into a sleeping person's ear, causing pain or even death. They generally have flattened bodies and at the end of their abdomens are a pair of forceps-like pincers for capturing prey or defense. Interestingly, the pincers of males are more curved, while those of females are straight. The wings are short and seldom used, with the forewings being harder and usually shorter than the hindwings. Some species may lack wings altogether.

Depending on the species, earwigs can be omnivorous or mostly predatory, and their flattened bodies allow them to creep into cracks and crevices to forage for food and also to hide from predators. They go through an incomplete metamorphosis in their life cycle, and the females are often observed to provide maternal care for the young, including guarding the eggs and feeding the nymph.

E) Flies (Order Diptera)

True flies (order Diptera) are easily distinguished from other flying insects by having only one obvious pair of flight wings - the hindwings have been modified to become tiny, club-like structures called halteres which help them to balance. Some are wingless.

Examples from Singapore include (clockwise from biggest picture) the long-legged fly, cranefly, houseflies, stilt-legged fly, hoverfly, and mosquito. Many fly species are important pollinators and predators of pests, but others could be parasites, carrier of diseases and pests of crops. Flies go through a complete metamorphosis in their life cycle.

F) True Bugs (Order Hemiptera)

True bugs (order Hemiptera) comprise a wide variety of insects, with diverse shapes, sizes and colours. They all have tube-like mouthparts for piercing into and sucking up their food, and while some are predacious, most species feed on plant sap. The wings can be membranous, or in some species the forewings may be partially hardened.

Some bugs (such as the jewel bug in the left-top picture) may be mistaken for beetles due to their partially hardened forewings, others (such as the planthopper in the middle) may be mistaken for a moth due to the broad wings, while some others (such as the cicada in the right-bottom picture) may be mistaken for flies due to the membranous wings. Hence, checking the mouthparts is probably a more reliable way when identifying unfamiliar species as bugs. The other bugs featured above include the Thespesia firebugs (middle-top), a backswimmer (right-top), a leafhopper (middle-bottom), and mealybugs (left-bottom).

Hemipterans go through an incomplete metamorphosis, and the eggs may be laid on plants or underground. Some species produce live young, and some can reproduce without mating. Due to their sap diet, many hemiterans, such as aphids, mealybugs, leafhoppers and cotton stainers are considered agricultural and garden pests.

Many bugs (such as the cotton stainers and the jewel bug) can secrete distasteful or bad-smell chemicals to deter predators. Some, such as the male cicadas, can make loud screeching noises to attract mates. This sound is created by repeatedly contracting the abdomen, making a continuous "click" sound which becomes a screeching sound when heard.

G) Bees, Wasps, Sawflies & Ants (Order Hymenoptera)

Bees, wasps, sawflies and ants (order Hymenoptera) form a diverse group of insects with a variety of behaviours and shapes. Their wings, if present, are joined in flight by tiny hooks, and the forewings are usually larger than the hindwings. Most species have a constricted waist, and many are eusocial insects living in huge colonies with caste systems. These colonies may have one or more egg-laying queens, with the bulk of the population comprising workers which gather food, feed the young, maintain the nest, and defend the colony. A colony may have one or more nests.

Examples of hymenopterans from Singapore include (clockwise from biggest picture) the spider wasp, the giant forest ant, the red weaver ants, the honey bee, and the cuckoo bee. Many bees and wasps have a stinger at the tip of the abdomen, and can give painful stings. The venoms of some wasp species are known to be lethal. While ants lack the stingers, many species can spray acid to deter predators. Many hymenopterans are important pollinators and very important in crop and fruit production. Some prey on insects and help to regulate pest population. The young undergo a complete metamorphosis.

H) Butterflies & Moths (Order Lepidoptera)

Butterflies and moths (order Lepidoptera) can be distinguished from other similar-looking insects by the tiny overlapping scales covering their body and wings, and most species (except some primitive groups with mandibles) the long, tube-like proboscis for sucking nectar and other liquid. When not in use, the proboscis is rolled up into a coil.

Technically, the butterflies are day-flying lepidopterans with club-shaped antennae, while all others without the club-shaped antennae are called moths. They are very important pollinators, though their young, the caterpillars, are sometimes regarded as pests since they feed on leaves. They undergo a complete metamorphosis.

The above photo features a Painted Jezebel butterfly with the caterpillars and pupa in the three pictures on top-left, and an Atlas Moth and its caterpillar and cocoon in the three pictures on the right panel. The bottom pictures features two unidentified moths and in the third bottom picture from the right, the protective case of a bagworm moth built with leaf materials.

I) Mantises (Order Mantodea)

Mantises (order Mantodea) can be recognised by their triangular heads with large, forward pointing eyes, giving them a binocular vision to seek out prey and judge distance accurately. When a prey is sighted, they will pounce and seize it very quickly with their modified front legs, which are armed with tiny spines so that they can have a firm grip. Most species have colours and forms which allow them to camouflage with their habitats. They are mostly diurnal, and feed on a wide variety of small animals, including small arthropods and even small frogs and lizards.

Mantises are also commonly known as praying mantises due to their habits of holding up their front legs as if in a prayer. They undergo an incomplete metamorphosis, and the eggs are laid in cases attached to plant parts. Male mantises are often eaten by the females during/after copulation, and the actual reason for this sexual cannibalism is still under much debate. The above picture features a variety of mantises seen in Singapore.

J) Netwings (Order Neuroptera)

Netwings (Order Neuroptera), or net-winged insects, comprise insects with net-like wing venations with many cross veins. The wings are equal-sized, and usually held over the body like a roof when not in use. They have chewing mouthparts, and some are known to bite when disturbed. They are mostly predatory, except a few that feeds on plant materials like pollen and nectar. Due to their predatory habits, they are sometimes used biological pest control against garden pests, such as aphids and mites.

Netwings undergo a complete metamorphosis in their life cycle. Many species have larvae with jaws to catch prey and curved mouthparts (forming a tube) to suck up the juices of the latter. The picture above features (clockwise from the left) a lacewing, an adult antlion, an antlion larva, and an owlfly. Antlion larvae are usually seen creating small round depressions on sandy grounds to trap passing ants. Owlflies are sometimes confused with dragonflies, but can be distinguished from the latter by the long antennae.

K) Dragonflies & Damselflies (Order Odonata)

Dragonflies and damselflies (order Odonata) are predacious insects with biting mouthparts, short antennae, very large compound eyes and membranous wings. Dragonflies are more robust and usually hold their wings apart to the sides at rest, while damselflies are more slender and tend to close their wings together above the long abdomen while resting. They undergo an incomplete metamorphosis, and the eggs are usually laid in water or on aquatic plants, since the nymphs live in water.

Both adult and young feeds on other arthropods and sometimes other smaller animals (the young may feed on small fishes and tadpoles), and hence they are sometimes regarded as important biological pest controls, especially against insect pests such as mosquitoes and houseflies. The picture above features a damselfly larva in the middle, and three dragonflies on the left panel, and two damselflies on the right panel.

L) Grasshoppers, Katydids & Crickets (Order Orthoptera)

Grasshoppers, katydids and crickets (order Orthoptera) can usually be distinguished from other insects by their tough, leathery forewings and enlarged/lengthened hindlegs adapted for jumping. Many species can produce sounds by rubbing their wings or legs, usually to attract mates. They have chewing mouthparts, and feed on plant materials. Some species can be very serious agricultural pests when they occur in huge populations and high densities.

Orthopterans go through an incomplete metamorphosis, and females usually lay their eggs in holes they have dug in the ground. A number of species are consumed by human. The above picture features three examples of grasshoppers on the left panel, a cricket in the right-top picture, and a katydid in the right-bottom picture.

M) Leaf & Stick Insects (Order Phasmatodea)

Leaf and stick insects (order Phasmatodea) typically have long, leaf- or stick-like bodies, blending nicely into the environment. They are usually slow-moving, and remain motionless when disturbed. These insects feed mostly on leaves. The males of many species have wings, but the females are usually wingless.

Leaf and stick insects go through an incomplete metamorphosis. The females may just drop the eggs or the ground, or attach them to plants. In traditional Chinese medicine, the droppings of stick insects fed with guava leaves are used to treat stomach complaints.

N) Barklice & Booklice (Order Psocoptera)

Barklice and booklice (order Psocoptera) typically have soft and short bodies with a relatively large head and long, thread-like antennae. Adults often appear humpbacked when viewed from the front or the sides. The wings are membranous, and are held over the back like a roof when they are not in use.

Psocopterans are herbivorous, feeding on a variety of plant or fungi materials, such as algae, lichen, pollens and other plant tissues. Some species are gregarious, while others are solitary. A number of species build a continuous layer of web over the stem and hide underneath, where they will feed and breed. They undergo an incomplete metamorphosis, with most species laying eggs and a few bearing live young. The above picture features two unidentified barklice and the web built by an unidentified barklice.

References

Bartlett, T. & J. VanDyk. 2003. BugGuide. Retrieved May 24, 2013, http://bugguide.net.
Burnie, D. 2001. Animal. London: Dorling Kindersley. 624 pp.
Ecological Research & Development Group. The Horseshoe Crab. Retrieved May 24, 2013, http://www.horseshoecrab.org
Koh, J. K. H. 1989. A Guide to Common Singapore Spiders. Singapore Science Centre, Singapore. 160 pp.
McGavin, G. 2000. Dorling Kindersley Handbooks: Insects, spiders and other terrestrial arthropods. London: Dorling Kindersley. 255 pp
Ng, P. K. L. & N. Sivasothi (eds.), 1999. A guide to the mangroves of Singapore II: animal diversity. Singapore Science Centre. 168p.
Ng, P. K .L., R.T. Corlett & H.T.W. Tan (eds.). 2011. Singapore Biodiversity: An Encyclopedia of the Natural Environment and Sustainable Development. Singapore: Editions Didier Millet. 552 pp.
Wang, L. K. & R. Tan. 2007. Fascinating Insects Of Singapore. (Guidesheet). Raffles Museum of Biodiversity Research.