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
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.
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