Monday, May 25, 2009

Echinoderm hangout at Changi

Echinodermata is my most favourite Phylum! In case you are not sure what is "phylum", it is a taxonomic rank where animals of similar distinctive traits are grouped together. They include sea stars, sea urchins, sea cucumbers, sand dollars, feather stars and brittle stars.

Probably the best mainland shore to find out more about Singapore's echinoderms will be at Changi! While most Singaporeans are snoozing away at 4am, the animals are all out during a super low tide this morning.

Not only do we have many sea stars, one can find a wide variety of different looking stars at Changi. The bigger sea star on the right is a Biscuit sea star (Gonodiscaster scaber). There are many biscuit sea stars at Changi in different sizes from very tiny ones to huge ones.

One of the many species of sea stars at Changi will be the Cake sea star (Anthenea aspera). Cake sea stars are known to come in different patterns and colours and this is my first time seeing one that has a red pigment at the centre of the star. How cool!

Yes, this is also a cake sea star and as for this particular star, it is in a stunning orange uniform colour.

As usual, the most abundant star in Changi must be the sand stars. And we usually see two different types, probably two different species. The left one is the Painted Sand star and the right one is the Plain Sand star (both Astropecten sp.).

And once in a while, one might also stumble upon the pretty orange-tipped Spiny sea star (Gymnanthenea laevis). If you are already confused about identifying these sea stars, you might want to check this out.

Chay Hoon shared with me her find of these two tiny yet delightful Luidia sand stars which are probably Luidia hardwicki. These are rare stars and I was of course thrilled to see them again. They have only been recorded from Sultan Shoal and the Pulau Ayer Chawan islands that have since been reclaimed to form Jurong Island. Last year, I had two occurence of these stars at around the same Changi location too. Glad that they are still around.

Knowing that this shore has other Luidia species, I went on to do more exploring and found yet another tiny Eight-armed sea star (Luidia maculata)! Though the much rarer six-armed sea star (Luidia penangensis) was not sighted (which Ron and friends saw it before), it was already quite a good day of starry finds!

Moving on to sea urchins, James found this yet another super tiny sea urchin that is probably the White sea urchin (Salmacis sp.). Shu Yi also found the bigger ones.

But I was more amazed at the huge mass of Black sea urchin (Temnopleurus toreumaticus). What intrigues me will be the large pool of the dead Asian date mussel (Musculista senhausia) at the same spot too. Is there any link between the sea urchin and the mussels? Hmmmm.

A closer look at the mass of the black sea urchin reveals more life like the octopus, a stranded fish, and the eggs of a drill.

Usually people only look at the spines of the sea urchin which are in black here. But they are like sea stars, in that they also have tube feet. Look closely among and in between the black spines to see the almost translucent tube feet.

And towards the end of today's trip, I chanced upon a solo Pencil sea urchin (Prionocidaris sp.). Being pink in colour with stripey patterns on its spines, it is prettier as compared to the black and the white sea urchins.

There are also many different types of sea cucumbers at Changi but I shall be biased to the more colourful ones like this Pink warty sea cucumber (Cercodemas anceps).

And Chay Hoon found the most special cucumber find which is the Sea apple sea cucumber (Pseudocolochirus violaceaus)! This is only my second time seeing this special sea cucumber on our shores.

These sea cucumbers are unfortunately harvested for the aquarium trade. Ironically, they do not make good aquarium specimens as they are often toxic to their tank mates.

There were also quite a number of Brittle stars (Subclass Ophiuroidea) zipping around the shore during low tide. My most favourite must be this stunning yellow brittle star.

More special finds of the day's trip here.

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