Wednesday, November 7, 2007

Semakau Island, Singapore (2): 28Oct07

Semakau Guides Explorary Trip

At West Coast Pier, we were greeted by some rubbish, suspected just dumped by some boat. The rubbish floated on the water and sometimes i really couldnt understand people who relies on the sea but yet 'trying' so hard to destroy it as well.

This sea hibiscus flowers are beautiful.
In mangroves, the sea hibiscus indicates the high water mark and the boundary between the end of salt water penetration and the beginning of freshwater swamp.

Sea lime. The skin is a bit bitter, so we sucked the juice and a bit of the flesh. It taste good. A mixture of sour and sweet.

This cute little fellow, mangrove horseshoe crab.
The mouth is in between of its legs.

Roy found this Scale Worm under the rock while trying to search for rock seastar, some other species of rock seastar (i don't fancy scientific name, so i couldn't remember it now :).
The free-swimming scale worm is brown, fuzzy in appearance and covered with a double row of oval-shaped scales which protect its body like an armour. They may be observed among brown and green seaweed or on the mud along the coasts.

The river mouth and the mangrove.
We have never had a chance to explore to this area during public walk.

Love is growing .... Common seastar.
Shh.... Don't disturb.

Reproductive biology of Seastar

Most sea stars have separate sexes with no visible differences between them. Internally, each arm contains a pair of gonads that become almost filled with eggs or sperm, depending on the sex, at the time of breeding. The majority of species are broadcast spawners where eggs and sperm are released into the water column to be fertilized. To increase the chances of fertilization, sea stars aggregate when they are ready to spawn. These events usually rely on environmental cues, such as day length, to coordinate timing and may use chemical signals to indicate readiness. The crown-of-thorns sea star, for example, releases a potent chemical into the water column to attract the opposite sex. Fertilized eggs rapidly develop into free-living bipinnaria and later brachiolaria larvae that are planktonic. Eventually, they undergo metamorphosis and settle on the seabed to grow into adults. This type of reproductive strategy is known as indirect-development.

... Too much theory... but doesn't this interesting?
Take a break with juvenile Knobby Star.

Some sea stars brood their young, where females hold their fertilized eggs in a brood space under the arm (e.g., Asterina phylactica), in the stomach (e.g., Leptasterias hexactis), or incubate them in the gonads (e.g., Patiriella parvivipara). In the last two cases, young develop internally and escape through small openings the female's body wall called gonopores. Many brooding sea stars inhabit polar and deep-sea regions. Some brooding sea stars, however, produce unguarded egg masses that they attach to the seabed (Asterina gibbosa).

Another break ...
This is the rock seastar that Roy was looking for.
He ended up found a few. :) ... Wish fulfilled.

Asexual reproduction is another method of development that involves either fission or regeneration of entire animal from arm parts. Almost a dozen species divide through their disc, producing clones with identical genetic makeup (e.g., Linckia laevigata). Seven species are known to voluntarily pinch off one or more arms (autotomous asexual reproduction) that subsequently regenerate a complete new disc and arms; these species tend to be very small. Even sexually reproducing animals can show asexual characteristics at different stages of their life cycle. For example, larvae can pinch off body structures capable of growing into another independent feeding larvae.

This poor fellow was under great stress when July caught it into a container. We finally released it to its anemone but it remained disoriented for quite a while.
Anemonefish (or clown fish) have a special symbiotic (mutually beneficial) relationship with sea anemones. Normally, the nematocysts (stinging cells) of an anemone's tentacles discharge when fish brush against the tentacles, paralyzing the fish.
The False-Clown Anemonefish is orange with black markings on the fins. It has a white bar on the head, body and caudal peduncle (the region of the body between the end of the anal fin and the base of the caudal fin).
The Clown Anemonefish was brought to international stardom in the Pixar animated film Finding Nemo.

Curryfish Sea Cucumber.
It seems like this kind of sea cucumber is commercially harvested in many countries as Chinese delicacy.
This one has long body and smooth underside. It is dark brown in color and covered with small orange spots.

Juvenile Damsel fish. Damsel fishes are generally very territorial. Their diet can include small crustaceans, plankton, and algae.

The petrol chemical plant, Bukom Island at night. Doesn't the chimney look like a decorated Xmas tree?

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