Hunting Seeking at P.Semakau

We were back at Pulau Semakau on 30 May to hunt & seek. Our primary task this time round, was to look for species of algae, particularly the unidentified ones. Yet another challenging task (second to seagrass transect), we ended up collecting samples of almost every species of algae we saw since we were not certain of their identity. Our guiding principle for the day was 宁可杀错 不可放过. =)

I was so focused on identifying the seaweeds that I only remembered to take photos of 2 species. =P

Algae, or seaweeds, do not have a root system and also rarely have strong supporting stem-like structure. Unlike many plants, it has no veins, no flowers and typically has a similar colour throughout the entire plant.

Now, if you think that seaweeds/ algae are only green in colour, you will be surprised (like how I was ,prior to joining this project) to know that they are commonly clad in red or brown too!

This algae, which I'm not sure of the species, is likely to be from the genus of brown alga Sargassum. However, we observed that it does not have a living life jacket ie special gas-filled sacs, to help it float.



We also saw plenty of Napoleon's hat (Avrainvillea sp). This green algae is velvety and soft to the touch. Unusally flattened, it grows on soft sand/ mud, with its fan-shaped blade sticking out from the substrate.



We were lucky to come across this Sea Anemone, likely to be the Giant Carpet Anemone (Stichodactyla gigantea). While they may looked harmless, their showy tentacles contains nasty stinging cells. The stings however, do not hurt human beings, but may leave welts on sensitive skin.

Carpet anemones may come in array of colours due to the presence of symbiotic algae (called zooxanthallae). The algae photosynthesizes to produce food and shares it with the sea anemone, which in return provides the algae with shelter and minerals.

Knowing that the sea anemone also has a symbiotic relationship with the Ocellated Clownfish(Amphiprion ocellaris), we embarked on the mission of 'Finding Nemo' and were elated to spot 2 clownfishes darting about its home (try spotting one in video below!)

The anemonefish escapes the stings of the sea anemone by secreting a special mucus that covers its body. It enjoys protection from the sea anemone and may also feed on leftovers of prey captured by the host. In return, it protects its host from predatory fishes such as butterflyfish, removes parasites/ dead tissues and may even attract other fishes for the sea anemone's consumption.

A few steps away, the Synaptid Sea Cucumber was gingerly lashing its feeding tentacles in the water to pick out tiny organic particles/ detritus. One of the longest sea cucumber in existance, it can grow up to 3m long! I am not sure how long this chap is, as most of the body was hidden in the seaweed. I was wary of checking out its length (using my metal chopsticks) because of its thin body wall that causes it to be more dedicate than other sea cucumbers.

If you touch it gently, you will realised that the Synaptid sea cucumber sticks to your hands. This is due to their hooked spicules (instead of tube feet) which poke out of its soft body - works just like velcro!

Although a master of camouflage, this common Hairy crab or fondly known as teddy bear crab (Pilumnus vespertilio) could not escape our keen eyes! It is covered with long hairs which traps lots of mud and detritus. When we placed it in water, the hair instantly puffed up, breaking the outline of this creature - its way of fooling its predators.

When I showed this picture to my friends whom I met after the trip, it was not surprising that they very quickly associated this common hairy crab with 大閘蟹/ 上海毛蟹. They were visibly upset when I told them that this hairy crab is not edible, instead it is mildly poisonous due to its diet of zoantids!

While it was a short trip, it was still a fruitful one. At least now I know Ascidians (which we innocently collected, mistaking it for algae) are animals, filter feeders and commonly known as sea squirts (due to their ability to squirt jets of water). Their small short-lived tadpole-like larvae has notochord, thus they belong to the Phylum Chordata, just like you and I!