Sunday, June 8, 2008

Semakau Inter-Tidal Walk on 7 June 2008

Sixty Second Discovery Posting:

Back at Semakau again, this time we were guiding a group of students from Jurongville Secondary and 'Octopus ' was the group of people I was guiding.

Side note:
I finally saw dolphins in our waters, actually SY spotted them as we were on the boat towards Semakau, I saw 3 dolphins while others spotted a total of 5! Wow! Too bad none of us managed to get a picture of them in action.

Here are the octopus-es or octopi on the move towards the forest trail which we had to go through before reaching the Inter-tidal area (picture below)
Upon reaching the Inter-tidal area, we headed straight out to escape from the mozzies, as we were literally 'food' for them. =P

After an explanation of the many things one can find if you look closely, seagrass and sponges, we proceed to cross the seagrass lagoon and with the a group photo (picture below).
After crossing the lagoon, we saw the first 'discovery' of the day, the ocellated sea cucumber (picture below).
Discovery Note:
1. Do you know they belong to the same phylum as the sea stars? This family is called echinoderms, or in simple terms, spiny skinned animals.
2. Sea cucumbers has a water vascular system compared to the blood vascular system for us (humans).
3. Therefore they will feel 'stressed' if removed from water, and when that happens, they may eject water, sticky threads or even their internal organs.
4. For this species of sea cucumber, this is said that they may eject their internal organs, and it's not hard to guess that if this goes on for too long, they will eventually die.

And the second 'discovery' is something related to the sea cucumber, the common sea star (picture below).
Discovery Note:
1. Yes, they belong to the same phylum of animals as the sea cucumber, the spiny skinned animals or echinoderms.
2. An interesting thing about some sea stars is that, when they feed, they actually push out their stomachs to engulf and digest food. They might also use their limbs to help engulf their food.
3. Some species take advantage of the great endurance of their water vascular systems to open the shells of molluscs (clams, mussels and the like), and inject their stomachs into the shells. Once the stomach is inserted inside the shell it digests the mollusk in place. Because of this ability to digest food outside of its body, the sea star is able to hunt prey that are much larger than its mouth would otherwise allow (including mollusks, arthropods, and even small fish)

Reference for point 3:

The octopus-es also spotted a number of hairy crabs as we explored the inter-tidal area. Third 'discovery' is one of them(picture below).
Discovery Note:
1. They are NOT the same hairy crab which some people eat.
2. They are actually poisonous due to what they eat, zoanthids or colonial anemones which scientists have found one of the most toxic poison in a type of colonial anemone.

Fourth 'discovery' is a cowrie, something which I have not taken a good photo for some time (picture below).
Discovery Note:
1. They have shells but it is usually covered completely by their mantle.
2. This mantle prevents algae and encrusting animals from settling on their shell.
3. The mantles of cowries have historically been used as currency in several parts of the world, as well as being used, in the past and present, very extensively in jewelry and for other decorative and ceremonial purposes, therefore the fate of over-collection for them.
4. They feed on algae and seaweed.

And for fifth 'discovery', we saw a puffer fish (picture below)!
Discovery note:
1. They are named for their ability to inflate themselves to several times their normal size by swallowing water or air when threatened.
2. They have four large teeth, fused into an upper and lower plate, which are used for crushing the shells of crustaceans and mollusks, their natural prey. They also enjoy the occasional bloodworm
3. The eyes and internal organs of most puffer fish are highly toxic, but nevertheless the meat is considered a delicacy in Japan and Korea.

We were really lucky today, as this is the first time I have seen a seahorse today (picture below)! Sixth 'discovery'.
Discovery Note:
1. Seahorses are poor swimmers, thus they are most likely to be found resting in sea grasses or coral reefs with their prehensile tails wound around a stationary object.
2. They have long snouts, which they use to suck up food, and eyes that can move independently of each other. Seahorses eat small shrimp, tiny fish and plankton.
3. An interesting fact about them is that the male seahorses actually carries the fertilized eggs into its pouch.
4. Depending on the species, a male seahorse can give birth to as many as 2,000 babies at a time and pregnancies last anywhere from 40 to 50 days.

The seventh 'discovery' is a marginated glossodoris nudibranch (picture below).Discovery Note:
1. 'Nudibranch' means 'naked gills'. The name comes from the flower-like gills found on the back of many nudibranchs. These nudibranchs use the gills to breathe.
2. Nudibranchs are related to snails. Little baby nudibranchs are born with shells, but they lose them when they become adults.
3. Most nudibranchs are carnivores, they eat immobile or small, slow-moving prey. Examples are sponges, ascidians, hard corals, soft corals, sea anemones etc.

And Octopus-es also got the chance to meet themselves, an octopus!

Here's another group shot of all Octopus-es at the southern most point of Semakau (picture below).
Thanks everyone for being attentive and fun, you were a great lot! =)

a) Read Tidechaser's blog entry on what his group saw.
b) Check out Manta's blog to see what he found as a hunter seeker.

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