Saturday, April 21, 2007

Semakau Walk on 21 April 2007

Am flying off to New Zealand this evening, so doesn't have much time to blog actually :P

Just a few pictures and some basic notes to record some of the things we saw.

We departed from Pasir Panjang Ferry Terminal instead of West Coast Pier today. Helen found a container with some red seaweed and some anemone inside in the female toilet. The male toilet was quite bare though. Still, the poor anemone probably won't be able to survive long... sigh...

Here a group shot of my group just before we entre the forest. They are from IDA and our group name is Sea Stars.

Even before we enter the sea grass lagoon, we found this scallop (Family Pectinidae).

Scallops are filter feeders - they open their shells slightly during high tide to suck in water and collect edible particles. At low tide, they will shut their shells tightly. Scallops can also "swim" by flapping their valves.

We also saw a pair of common sea stars (Archaster typicus), getting ready to perform external fertilisation.

During high tide, the male (on top) and the female (bottom) will release sperm and eggs together. These sea stars can actually burrow into the sand! As a sea star uses sea water to support its body and move its little tube feet. Thus, never take them out of seawater for too long, as it is very stressful for them.

And here's the traditional shot of the group crossing the sea grass lagoon...

As we stepped onto dry land again, we have this sandfish sea cucumber (Holothuria scraba) waiting for us.

This sea cucumber is edible, but must be properly treated before consumption.

On a rock in the coral rubble, we found a cute little onchidium sea slug (Onchidium sp.)! Can you find it in the photo below?

And of course, there was no lack of the master of camouflage - the hariy crab (Family Pilumnidae)!

It can be quite difficult to spot them sometimes since they blend in very well with the rocks.

We saw several pretty fanworms (Family Sabellidae), and here's one of the orange ones we found.

These worms live in flexible tubes. The feathery fan, which is stuck on the worm's head, is used to filter edible particles in the water so that the worm can feed on them.

We found a lovely sunflower mushroom coral (Heliofungia actiniformis) in one of the tidal pools too.

They usually come in brown, but this one was in a lovely shade of green, probably due to the colour of the symbiotic alge (aka zooxanthallae) which lived in it. The algae can actually provide the coral with food from photosynthesis.

There were lots of other hard corals (below top 2), soft corals (below bottom left), and sea anemones (below bottom right) too.

And we also saw several sponges. Here's a Neptune's cup sponge.

And the highlights of the day were usually these knobbly sea stars (Protoreaster nodosus).

And here's the traditional group shot taken with the knobbly sea stars.

We also saw some egg capsules. These were probably squid eggs.

We also saw a few nudibranchs. The name nudibranch actually means "naked gills". Below is a polka dot nudibranch (Jorunna funebris).

Most nudibranchs can secrete chemicals that make them very distasteful or even toxic, while others harbour stinging cells from the animals they feed on.

The nudibranch below is a pustulose phyllid nudibranch (Pyhllidiella pustulosa), which is said to be able to secrete toxins when they are stressed.

The one below is not a nudibranch though, but a sacoglossan, or what we call a sap-suckling slug. This is probably a Thuridilla gracilis.

They normally feed on algae by biting a hole on the latter and suck the cell sap out of it.

We saw a flatworm (Class Turbellaria) too!

Flatworms are so flat that they can easily crawl into tiny cracks on the rocks to hide from predators and also to find preys.

And here's a noble volute (Cymbiola nobilis).

These huge snail normally feed on clams and other shells.

And there were also two cute upside-down jellyfish (Cassiopea sp.).

This jellyfish has symbiotic algae, mostly in its tentacles, which photosynthesises better with it being upside-down. Some of the food made by the algae will leak and get absorbed by the jellyfish.

And on our way back, I saw a trail and scooping under the sand, I found a moon snail (Family Naticidae). It has a really smooth and pretty shell.

I found a heart cockle too!

Well, on the whole, we had a great trip today. Thanks to all the enthusiastic visitors!


TS said...

Have fun in ur trip! And wish me luck in my exams too :)

Ron Yeo said...

Thanks! And good luck for your exams :)

nadz ruslan said...

woa i never seen that much at beaches i've visited so far. that was sooo much fun!!!!

Naidu, SA said...

Hai here i saw new photos of benthos,good work