Sunday, August 31, 2008

Biggest Sea Star in Singapore?

All along, I had thought that the knobbly sea star (Protoreaster nodosus) was probably the biggest sea star in Singapore based on diameter. But that has changed after I saw this carcass this morning.

Went to Changi Beach again, and was about to head back when KS shouted to me. He had found a dead sea star, and it was HUGE!!! Just compare it with my foot. KS has a ruler with him, and we measured it to be about 60cm wide! Ok, I do understand that in other countries, they have sea stars more than a metre wide, but somehow I had never even hoped that with the little wild shores we have left, we can actually find such a huge sea star here!

In fact, we found a total of 4 such dead sea stars! Taking a closer look at them, we decided that they are probably the 8-armed Luidia sea stars (Luidia maculata), but we definitely have never seen such huge specimens during our shore trips before.

Luidia maculata
Here's how the sea star should look like when it's alive. The above photo was taken a few years ago at Beting Bronok, a reef near Pulau Tekong. It was mentioned in "A Guide to Sea Stars and Other Echinoderms of Singapore" that specimens of this sea star often exceed 20cm in radius, so why haven't we seen one of the bigger ones alive?

Could it be that they are only found in the subtidal zone? Do they migrate to a different habitat when they mature? Whatever it is, I'm definitely going to visiting this same spot again more regularly in future.

Anyway, KS and I went to Changi to look for other Luidia species - L. hardwicki and L. penangensis. We didn't managed to find any of them though. However, we had plenty of other interesting finds to keep us occupied, apart from the huge 8-armed sea stars that got us really excited.

Cake sea star, Anthenea aspera
KS spotted this pretty pinkish cake sea star (Anthenea aspera). Cake sea stars are rather common at Changi, but this was the first time I saw a pink one!

Cake sea star, Anthenea aspera
Most of the time, the cake sea stars we saw had rather dull colours, like the one above, though we had occasionally seen bright orange or red ones before.

Four armed Gymnanthenea laevis starfish
I also found this four-armed Gymnanthenea laevis sea star.

Gymnanthenea laevis starfish
They normally come with 5 arms.

Biscuit sea star, Goniodiscaster scaber
Biscuit sea stars (Goniodiscaster scaber) are also very common here, but this was the first time I saw such a pretty one in bright orange.

Biscuit sea star, Goniodiscaster scaber
They are usually brown in colour.

Warty sea cucumber, Cercodemas anceps
The warty sea cucumber (Cercodemas anceps) appeared to be in season, and we saw several of them.

White Salmacis sea urchin
The white Salmacis sea urchin (Salmacis sp.) seemed to be making a come back too.

This unfortunate stingray was caught and killed by a disused fishing line.

Spotted seahorse, Hippocampus kuda
I also found a spotted seahorse (Hippocampus kuda) that's orange in colour instead of the usual yellow or brown!

While I didn't managed to find the sea stars I was looking for, it was nonetheless still a really exciting and colourful trip! :)

Saturday, August 30, 2008

Starry Changi

My luck wasn't too good the last time I explored Changi Beach, so decided so pay another visit to it today with a few other friends. And it seemed like my luck has improved this time round. We saw lots of interesting stuff, including many sea stars!

Among the various Singapore shores that I've visited, Changi probably has one of the most variety of sea stars.

Sand star, Astropecten sp.
The most commonly encountered one must be the sand star (Astropecten sp.), which feed on small bivalves by swallowing them whole. It has pointed tube feet which allow it to burrow quickly into the sand.

Rock stars, Asterina coronata
At the rocky area, there were plenty of rock stars (Asterina coronata). Most rock stars are brownish in colour, which allow them to camouflage very nicely into the surrounding. But once in a while, we encounter some, like the one above, which are brilliantly coloured.

Six-armed sea star, Luidia penangensis
As we were walking along the upper, ST found this six-armed sea star (Luidia penangensis) stranded on the sand.

Underside of six-armed sea star, Luidia penangensis
Looking at the underside, we can see the orange tube feet. This sea star supposedly feeds on other smaller sea stars by swallowing them whole!

Starfish, Luidia cf. hardwicki
SY later found another one. Initially, I just assumed that it should be an L. penangensis as well, until after the trip ST told me he found the colour to be kind of pinkish, similar to another Luidia that KS found recently. Unfortunately, we didn't take any photos of its underside. I decided to blow up some of the photos I've taken to see if I can spot any tube feet.

Starfish, Luidia cf. hardwicki
And in one of the photos, I managed to see some tube feet as the sea star lifted up its arm! And it's not orange in colour! Could it be a six-armed variety of the sea star that KS saw last time? We thought it could be a Luidia hardwicki, but these days I'm beginning to wonder if it could be some other species that hasn't been recorded.

Biscuit sea star, Goniodiscaster scaber
Anyway, at another patch of exposed shore, we saw lots of biscuit sea star (Goniodiscaster scaber).

Starfish, Gymnanthenea laevis
And also, several Gymnanthenea laevis.

Cake sea star, Anthenea aspera
As the tide was rising, I also found a cake sea star (Anthenea aspera).

Pink thorny sea cucumber, Colochirus quadrangularis
We also saw several sea cucumbers, inlcuding the pink thorny sea cucumber (Colochirus quadrangularis) above among the green algae and red algae.

Ball sea cucumber, Phyllophorus sp.
There were several ball sea cucumber (Phyllophorus sp.) emerging from the sand too. This one has a hermit crab next to it.

Orange striped hermit crab, Clibanarius infraspinatus
And here's the orange striped hermit crab (Clibanarius infraspinatus).

Hell's Fire Anemone (probably Actinostephanus haeckeli)
I also found an uncommon Hell's Fire Anemone (probably Actinostephanus haeckeli). Have seen several other species of Hell's Fire Anemone from the Actinodendron and also probably the Megalactis genus, but this is the first time I'm seeing one an Actinostephanus! Was rather excited about this :)

Sea anemone
Also saw several of this anemone that we always see at Changi, but have no idea of the exact ID.

Tube anemone
There we lots of tube anemones too! They were like bunches of flowers scattered around the intertidal aarea. Very pretty!

Striped eeltail catfish, Plotosus lineatus
We also found a striped eeltail catfish (Plotosus lineatus) in one of the tidal pools. Earlier, we saw a whole school of juveniles swimming around, but unfortunately, the water was too murky to take any decent photos.

There were several halfbeaks (Hemiramphidae) swimming near the water surface too.

Again, this was a good trip with several interesting finds. Changi is surely one of my favourite local shore! :)

Tuesday, August 19, 2008

Otter at Sungei Buloh

Today, SY and I went to Sungei Buloh Wetland Reserve and Kranji Nature Trail for a recce. Have to say that we were really lucky, because the moment we stepped onto the main bridge, we saw a smooth otter (Lutrogale perspicillata)!

Smooth otter, Lutrogale perspicillata
It was swimming around, hunting for fish.

Smooth otter, Lutrogale perspicillata
After a while, it got one!

Smooth otter, Lutrogale perspicillata
The otter then swam over to a pillar of the main bridge to feast on its catch.

Smooth otter, Lutrogale perspicillata
But probably got tired of swimming and eating at the same time...

Smooth otter, Lutrogale perspicillata
So it swam over to shallow water under some mangrove trees instead.

Smooth otter, Lutrogale perspicillata
Got startled by a plantain squirrel jumping on the mangrove tree near it.

Smooth otter, Lutrogale perspicillata
The last few mouthful... Yum yum!

Really glad that I decided to take a cab in instead of waiting for the bus. I could have missed all these by the time I walk all the way from the bus stop to the reserve!!!

And now, finally, I have a few decent shots of a smooth otter :)

Anyway, here are some of the other interesting things we saw at Sungei Buloh and Kranji Nature Trail.

Managed to find a little mangrove horseshoe crab (Carcinoscorpius rotundicauda) at the usual area below the mangrove boardwalk. Had to look really hard though, since it was really small and it's definitely not easy trying to find something so small looking down from the boardwalk.

Several violet tree-climbing crabs (Episesarma versicolor) were resting in a hole on a tree.

Beneath one of the shelters, there were lots of mangrove anemones.

And of course, Malayan water monitors (Varanus salvator) were a common sight.

We also saw this stork-billed kingfisher (Pelargopsis capensis) looking at its own reflection in the window pane.

While we were taking photos, it jumped around and faced us a few times before jumping back to face the window pance again.

We also saw a few Pacific swallow (Hirundo tahitica) at Kranji Nature Trail.

And a spider with eggs!

Several huge golden orb web spiders (Nephila spp.) were spotted too.

We also saw a few small red coloured spiders on the web of the golden orb web spider, which were probably parasites feeding off the latter's catch. One of the little spiders could be the male golden orb web spider though :P

Sunday, August 17, 2008

Semakau Walk on 17 Aug 2008

We were out on Semakau on a guided walk again. This time round, my group name was "Volute", and I had D with me doing on-the-job training.

It was a very pleasant morning when we set off from Marina South Pier - cooling, but not windy. On the boat, we were talking about it being full-moon, and so it should be rather bright relatively when we make our way to the intertidal area. So you can imagine how surprised we were when we saw this:

lunar eclipse
The first thing that came to my head was - did I remember wrongly and we're not supposed to be having full moon today? And then, it suddenly dawn on me that we're witnessing a lunar eclipse! Wow!

That was certainly a very nice start for the guided walk! Anyway, as per most of the walks I led, I couldn't really spare much time to take photos. So please pardon the quality :P

Gigantic anemone, Stichodactyla gigantea, with anemone shrimp
As usual, the resident gigantic anemone (Stichodactyla gigantea) was waiting for us at the same spot, and so was the anemone shrimp. Not sure what has happened to the bigger female shrimp though, as I had been seeing the male only for the past 2 trips. Anemone shrimps (Periclimenes brevicarpalis) are commonly seen on several species of sea anemones at our reefs. The shrimps usually scavenge for food among the tentacles of the anemone. When there is insufficient food, it may actually feed on the anemone’s tentacles! They protect themselves from the anemone’s stinging cells by coating their body with the mucus secreted by the anemone.

Kite butterflyfish, Parachaetodon ocellatus
And in the very same tidal pool, I saw this kite butterflyfish (Parachaetodon ocellatus). I've seen such butterflyfish feeding on carpet anemones before. Was it happily feeding when the tide went down too quickly, thus trapping it in this little tidal pool? Hmm...

Stinging anemone, Family Aliciidae
Another resident anemone we saw was this stinging anemone (Family Aliciidae), which supposedly gives painful stings. Been seeing it around the same spot for the past few months! Seemed to have grown bigger though :P

Acanthozoon flatworms
It was certainly a morning for Acanthozoon flatworms (Acanthozoon sp.), and I saw at least 10 of them. Being very flat and fragile, they tear very easily, so please avoid handling them. Fortunately, they can regenerate lost body parts, and I'll assume that to be a painful process.

Sunflower mushroom corals, Heliofungia actiniformis
We saw several sunflower mushroom corals (Heliofungia actiniformis) too. They have long tentacles, and are thus often mistaken to be anemones.

Funeral nudibranch, Jorunna funebris
We saw several species of nudibranchs (Order Nudibranchia) too, and I'll just highlight some of them here, such as the funeral nudibranch (Jorunna funebris) above. This one looked really fat. Wonder if it's pregnant or something. Anyway, "nudibranch" means "naked gills", refering to the flower-like gills on the back of many species of nudibranchs.

Glossodoris nudibranch, Glossodoris atromarginata
Nudibranchs are also hermaphrodites, meaning they have both male and female reproductive systems. When they mate, they usually fertilise each other in a 69 position, and it appeared that the glossodoris nudibranch (Glossodoris atromarginata) above were doing just that!

Discodoris nudibranch, Discodoris boholensis
This little fellow looked very much like a flatworm, but is in fact a discodoris nudibranch (Discodoris boholensis)! Look closely and you may be able to see the gills on its back.

Swallowtail headshield slug, Chelidonura pallida
We also had an uncommon sighting- a swallowtail headshield slug (Chelidonura pallida)! This was the second time I've seen this slug on Semakau! Like other headshield slugs (Order Cephalaspidea), the swallowtail headshield slug has well-developed headshield, which is a broadening at the head used to plow beneath the sand surface and help prevents the sand entering the mantle cavity. The term "swallowtail" refers to the characteristic long split in the tail, of which the left side is always longer than the right. These slugs feed on tiny acoel flatworms living on coral reef substrate.

Headshield slugs "smell" or sense their prey with a pair of round, bristle covered structures on either side of the head. These sensory structures are used also by the slugs to find mates too!

Sand-sifting sea stars, Archaster typicus
We saw several species of sea stars too. The above are sand-sifting sea stars (Archaster typicus) in a shallow tidal pool. Interestingly, the one with four arms kept sliding over the pair which were getting ready for fertilisation. Not sure what was it trying to do.

Cushion star, Culcita novaeguineae
We were quite luck to saw a cushion star (Culcita novaeguineae) too. This one appears to be a different individual from the previous 2 that we've seen on our walks, as the markings and colours on its back are different. Cushion stars feed on corals.

Knobbly sea star, Protoreaster nodosus
And one of the highlights of the day will be seeing the knobbly sea star (Protoreaster nodosus). This is probably the biggest sea star in Singapore based on body width, and can grow to about 30cm wide. This sea star apparently feeds on micro-organisms on seagrass or sediment surface, but is known to feed on soft corals, sponges, clams etc in captivity as well. However, they are not known to survive long in captivity, which suggest that the latter may not be the preferred natural diet.

Knobby starfish, Protoreaster nodosus
We also saw this knobbly sea star again which didn't look too healthy. We saw it during our last walk which it already look rather unwell, but before that we had not seen it for more than a year. Several of its knobs appeared to be missing.

And here's a group shot of the the Volutes...

Dragonfish sea cucumber, Stichopus horrens
We had quite a bit of luck with sea cucumbers too, and saw 4 out of the 5 sea cucumbers commonly seen on Semakau. The above is a dragonfish sea cucumber (Stichopus horrens). This interesting sea cucumber gets very stress when it's out of water for too long, and in fact, is known to somewhat "melt" and disintegrate if left in the hot sun for too long, and may eventually die unless it's returned to water before it's totally gone.

Sandfish sea cucumber, Holothuria scabra
This sandfish sea cucumber (Holothuria scabra) is the one often served in Chinese restaurants. They must be probably treated to remove their toxin before they can be consumed though.

Ocellated sea cucumber, Stichopus ocellatus
This pretty ocellated sea cucumber (Stichopus ocellatus) which has lots of "eyespots" on its body, which are basically dark papillae surrounded by a white ring.

Synaptid sea cucumber, Family Synaptidae
This worm-like thing is actually a synaptid sea cucumber (Family Synaptidae). When fully stretched, it's probably about 2m long!

Noble volutes, Cymbiola nobilis
My group name was "Volute", and we're quite lucky to spot 3 noble volutes (Cymbiola nobilis) with their eggs. It's always nice to see animal eggs here, as it just shows how much alive our shores are! The juveniles will eventually hatch as little snails crawling out of the egg capsules.

Spiral melongena, Pugilina cochlidium
We also saw a spiral melongena (Pugilina cochlidium) laying eggs! This snail supposedly feed on barnacles.

Mangrove horseshoe crab, Carcinoscorpius rotundicauda
Our hunter-seeker also found us a mangrove horseshoe crab (Carcinoscorpius rotundicauda). This is a living fossil that existed even as far back as more than 400 million years ago! Known to be scavengers, Mangrove horseshoe crabs are also known to feed on worms and clams. The mouth is located on the underside, and interestingly, they have no teeth! Basically, they grind their food with their legs as they move around!

Little egret, Egretta garzetta
We also saw a little egret (Egretta garzetta) hunting for fish, rushing around the among the shallow tidal pools to flush out its prey.

On the whole, this was certainly a great day with lots of interesting sightings!