Saturday, May 10, 2008

Semakau's cryptic stars

The team seagrassers are out at Semakau today. After a downpour and some rain, we did our monitoring of seagrasses. Not long after I completed my transect with my partner, Ria called out to me and shares with me her find of the cryptic stars.

This is the underneath of a rock and if you do not notice closely, you might have missed the cryptic stars (Cryptasterina sp.).

According to Dr Lane's "A Guide to Sea Stars and Other Echinoderms of Singapore", the cryptic stars live amongst rocks and stones on the upper to mid-shore level. They have a mottled, but variable, colouration which is actually for camouflage to be inconspicious to predators. That's how their name come from and also why their colors are quite close to that of rocks as shown in photograph above.

It is also noted that these cryptic stars can also occasionally come in 4 or 6 arms known normally will be 5 arms like the ones we found. Check out the sixed armed one at July's discovery blog.

Dr Lane stated in his book that species identification is difficult and subtle differences can only be differentiated by molecular methods.

Dr Lane had recorded these cryptic stars from Pulau Semakau before too. The aboral surface shows the mottled yet variable colouration.

Another cryptic star's aboral surface.

The third star's aboral surface. As you can see, they do not look exactly the same.

The underside of these interesting sea stars show even nicer patterns, in my opinion :-)

Below are the oral views or underside shots of the three different cryptic stars. These stars actually feed on algae or small animals attached to rocks.

Furthermore, Dr Lane says in his book that "undisturbed rocky shore habitats suitable for this sea star tend to be rare and vulnerable in the tropics, including Singapore, and this, together with the tendency for speciation of isolated populations, has implications for biodiversity and conservation."

In all, it's exciting to see these cryptic stars for the first time. So next time when you encounter rocks on the mid to high shore area, turn it around- you might see something interesting. But don't forget to turn them back yeah ;-)

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