Monday, October 20, 2008

Exploring Big Sisters

Yesterday, the Semakau guides had an opportunity to go on an exploratory trip to Big Sisters island.

Trying to ID the two species of turban shells that we have locally, I spotted one, probably Turbo burneus (from its rougher operculum) that has white stuff stuck onto its shell. That is probably the eggs of the nerites (Nerita sp.) that were found all over the sea wall. Weird that they will lay them on another live animal though~

This should be the other turban shell, Turbo intercoastalis with its smooth operculum or "cat's eye". These marble like covering was used as buttons in the past.

While we were looking all over the exposed lagoon, July went to search for the endearing land hermit crabs (Coenobita sp.). He found many under a tree and there was one that was too big to hide into its spiral melongena shell (Pugilina cochlidium) so we were able to get a good picture of it.

Octopi are very common in our shores and Robert managed to find one stationary on a rock.

Squids can be normally identifiable by its pair of arrow shaped fins at the end of its body. They also have a thin, transparent quill shaped bone in their body.

There were several genera of hard corals in this lagoon. This is a lettuce coral, Pectinia sp. It can produce lots of muscus when disturbed and it is thought to be one way that can help to remove sediments from itself.

Robert saw this beautiful florescence green Euphyllia sp. Also known as the anchor corals, their tentacles normally end in the shape of an anchor.

This is a turban coral, probably Turbinaria mesenterina. They were so named as some of them can become highly convulated, especially under shallower waters, which is likely to be an adaptative to screen off excess light.

Palythoa tuberculosa
This mat of stuff are zoanthids (Palythoa tuberculosa). Many zoanthids, including this species, incorporate sand to strengthen their tissues as I learnt from Ria's posting when Dr James Reimer came to Singapore.

There were lots of red swimming crabs (Thalamita spinimana) at night. This one was grazing on algae. Swimming crabs belong to the family of crabs called Portunidae and they are characterised by their last pair of paddle-shaped legs.

July and the girls found this reef hermit crab (Dardanus lagopodes) inside a spider conch. This was only my second time seeing this, the first from Raffles Lighthouse.

To me, the most interesting find is this orange moon snail with a pretty translucent mantle. I will try to check out the ID later. Update >>> One of our local molluscs expert, Siong Kiat helped to place an ID on this moon snail. It is Natica zonalis.

There was another moon snail beside it. This pearly white moon snail (Polinices mammatus) is probably the most common species in our shores.

Towards the end of the trip, RY found a school of striped eeltail catfish (Plotosus lineatus), seeking safety in numbers.

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