Friday, May 1, 2009

Semakau walk on Labour Day

Today is a Labour Day but that doesn't stop us from exploring the marvellous shore at Semakau!

I was with my group, Jellyfish today at the intertidal area for a guided walk. They are from NUSS and are enthusiastic and sweet participants throughout the morning. We learnt much about the importance of seagrasses and understood why we need a death zone to prevent trampling. And this death zone is already a great place to pose for a whacky photo... since they are all wet! :-)

Oh, we saw lots of marine life but I won't be blogging about all of them as it was difficult to guide and take a good photo at the same time.

Nevertheless there are creatures that I cannot resist taking a photograph. Like this handsome spider conch (Lambis lambis). The spines on the shell improves stability and prevents the snail from toppling over as it hops.

Soon, one of the eagle eyed participants found another smaller spider conch! I personally think that the smaller spider conches have more patterns on the underside of their shell. The spider conch has a curved, knife-shaped operculum (in brown) attached to a long strong foot (in greyish green here). This is used by the animal to 'hop' along the surface.

Another stunning snail will be this noble one... because it is called a Noble volute (Cymbiola nobilis). Anyway, it has a pretty fleshy body that is black in colour with bright orange spots.

Finally for a change, I got to see a juvenile Fluted giant clam (Tridacna squamosa) in the wild for the first time myself. Mei Lin is the expert in clams as she works with many of her own baby clams for research purposes.

The cup shaped structure by the side of this giant clam is called the scute. It has been recently researched to have anti-predatory functions especially against crabs. This giant clam is out of water so you do need see its mantle fully exposed.

The Knobbly sea star (Protoreaster nodosus) is definitely the attention seeker and everyone loves to take group photo with this charismatic animal. I heard later that there was an upside down jellyfish next to it but I guess the attention was diverted away from it.

Though used to be very common in the past, knobbly sea stars are harvested from the wild for the live aquarium trade, often selling for only a few dollars. In captivity, they are unlikely to survive long without expert care. They are now listed as 'Endangered' on the Red List of threatened animals of Singapore.

Talking about sea stars, the rest later also saw a juvenile cushion star! Wow.

The hunter seeker did a great job and also found this Tiger-tailed seahorse (probably Hippocampus comes). Seahorses reproduce in a peculiar way. Why? It is because the males instead of the females that carries the eggs in his body and thus becomes 'pregnant'.

Corals wise, my most favourite is still the Sunflower mushroom hard coral (Heliofungia actiniformis). This coral, unlike most other hard corals, is one individual polyp (aka one animal) and it is free living. We also did saw many other types of corals!

I was surprised to see clusters of these blue ascidians. If I can recall, I have only seen green ones before! Could this be another species?

On the way back, we saw another two noble volutes, but this time they have laid their egg cases which will hatch baby snails in the future!

Nearer back to the mangroves, I saw this live Wandering cowrie (Cypraea errones).

Cowries produce among the most beautiful and highly prized shells. One cowrie was even used as currency by Polynesians in the past. However, I still think that a living cowrie, like this one, is even more fascinating than an empty shell of a dead cowrie.

One of the participants found this snapping shrimp that create clicking sounds to stun away predators. You usually hear them more than you see them in the shores.

Before we end the intertidal walk, it is nice to also share about "kiasu" mangrove trees in this case the Bakau trees that practice vivipary. What is this weird term?

According to the online Chek Jawa guide, the fruit of mangrove trees like the Bakau does not fall away when it ripens. Instead, the single seed within the fruit starts to germinate while it is still on the mother tree, and the mother tree channels nutrients to the growing seedling (which means vivipary). The seedling forms a stem. When the seedling finally falls, at first it floats horizontally, and drifts with the tide. It can survive for long periods at sea. After some weeks, the tip gradually absorbs water and the seedling floats vertically and starts to sprout its first leaf from the top, while tiny roots grow from the bottom. When it hits mud, it grows more roots to anchor itself upright, and then more leaves.

Sounds quite complicated but that is how mangroves have to adapt to living in such an environment. :-)

Today's trip was fantastic, though we were all tanned with the scorching sun. But the most special highlight of today's walk must be the dolphin sightings of today!

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