Friday, January 01, 2010

New Year's Day on Pulau Hantu

It's New Year's day, and we were at Pulau Hantu doing our recce for our upcoming intertidal walks. Unfortunately, even before we went onto the intertidal area, it started pouring, and didn't stop until about an hour later.

Still, we were really thankful that it did stop after all, and our trip was not wasted sitting inside the shelter.

Sargassum Bloom
But when we reached the reef area, we were greeted by a sargassum bloom! Almost everything was covered, and we could hardly see anything! We had to move near the edge of the sargassum bloom most of the time as we won't know what we were stepping on if we were to go into middle of it!

Still, at the edge of the bloom, there were a number of things to see.

Lobed Leather Coral (Lobophytum sp.)
Hantu has lots of these Lobed Leather Corals (Lobophytum sp.). These are soft corals, and do not have the hard calcium carbonate skeleton that hard corals possess. There are still colonial animals though, comprising lots of coral animals (aka polyps) connected by a shared tissue. Many of these colonies are known to be able to secrete chemicals to prevent other encrusting organisms from growing over them.

Red Egg Crab (Atergatis integerrimus)
I came across this huge Red Egg Crab (Atergatis integerrimus) trapped in a small tidal pool. This crab got its common name from its somewhat oval-shaped carapace. While the Red Egg Crab may look like a "cooked" crab since it is red in colour, it is certainly not something you want to have for a meal. This crab is known to be mildly venomous, and its bright colour advertises this fact to would-be predators that they are no good for eating.

Bohol's Nudibranch (Discodoris boholiensis)
The only nudibranch I found was this Bohol's Nudibranch (Discodoris boholiensis), and it certainly did not look too healthy, probably due to the rain earlier which exposed it to too much fresh water. The term "nudibranch" means "naked gills", refering to the exposed gills on the back of most species. This nudibranch has a rather interesting defence mechanism - it is able to break off part of it's wide mantle skirt when disturbed. So while the predator is distracted by the broken bit, it escapes to safety.

Tigertail Seahorse (Hippocampus comes)
One of the volunteer found this Tigertail Seahorse (Hippocampus comes). This seahorse is a female, and I know because it lacks a pouch on its belly, but has a protruding structure called an ovipositor instead. This ovipositor is used for depositing eggs into the male's pouch. And indeed, male seahorses are among the best fathers in the animal world! They are the ones who will carry the eggs, fertilise them, and protect them until they are hatched! So if you see a pregnant seahorse next time, take note that it is a male seahorse, not a female.

Red Shrimp
As we were heading back to the lagoon, I came across this little red shrimp, which I had no idea of its ID.

Phymanthus Anemone
There were several Phymanthus Anemone (Phymanthus sp.) too. While they look like flowers, sea anemones are actually animals that need to feed on other things to gain energy. To feed, they sting and capture small animals with their stinging tentacles, and move them to the mouth in the middle. The meat and soft tissues will be digested, while the hard skeleton or shells will be spitted out. So as you can see, they have no need of an anus, since everything goes in and gets out from the same opening!

Black Flatworm
We also saw a few flatworms, including this back one, possibly a Pseudoceros sp. Flatworms got they name from there very flat bodies that are seldom more than 1 mm thick! Being flat has it advantages, as it can easily squeeze into narrow cracks and crevices to escape from predator and also to seek for small or sessile animals they feed on in these places. However, being flat also means that they are very fragile and tear easily when handled, so please do not hold up a flatworm when you see one.

Branching Hard Corals (Montipora sp.)
As we were in the lagoon, I noticed several huge colonies of Branching Hard Corals (Montipora sp.). Like the soft corals mentioned earlier, these colony comprise lots and lots of polyps living together. But unlike the soft corals, they have a hard calcium carbonate skeleton instead of a shared tissue. Most hard corals exhibit a characteristic brownish tone, as they harbour a golden brown algae inside them. Called zooxanthellae, these algae photosynthesizes and share some of the food with the coral, and in return, the hard coral provides a shelter and nutrients from its waste products for the algae.

Sand-sifting Sea Stars (Archaster typicus)
Just before we left the lagoon, we saw lots of Sand-sifting Sea Stars (Archaster typicus)! These sea stars burrows into the sand to escape predators and to feed on the tiny decaying matter among the sand particles, hence the common name. The above photo shows two sea stars that had paired up! The one on top is the male. No internal fertilisation takes place while the sea stars are pair up in this position, and thus this behaviour is called pseudocopulation, which basically means fake sex. They may pair up for up to 2 months before they spray their eggs and sperm into the water. It is believed that chances of fertilisation is higher when they are in this position.

We saw a number of dead heart cockles too, and Peiya eventually found a living one. Unfortunately, I wasn't there when she found it, so did not have a photo. Check out Marcus's new blog for the photo :P

All too soon, it's time to go! Fortunately, despite the rain, we still managed to had a good time and finalised the route we would during the guided walk! :)

Afternote: Heard that Ivan got stung by a stonefish. Do hope that he will get well soon!

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