A quite overdued post, was super busy these days =/ Haha. Went to Semakau for Walk last sunday. It was my 3rd OJT and my lead guide was Marcus! (: LOL. We had a group of bio students from Xinmin Sec and a bio teacher attached to our group. I was supposed to guide half of the stations.. and I believed there's a super big room for improvement. LOL. And I managed to snap a few shots every now and then. Haha.
Marcus in action introducing the Bakau Tree (Rhizophora sp.)! The Bakau Tree is one of the mangroves that are more common in Singapore. Mangroves are very important as their roots can help to hold the soil together and prevent soil erosion. They're also homes for many intertidal animals like the mudskippers. Mangroves have adaptation like prop roots to help them balance on the unstable ground. As the ground is mostly made up of slit and mud, it is low in oxygen, so the exposed prop roots can take in oxygen from the atmosphere.
One animal that lives around the roots of the Bakau trees is the Porcelain Fiddler Crab (Uca annulipes). The males of the Fiddler Crabs have a super big claw to attract the attention of their mates, and also to fend off other males. This is very important in the animal world as they need to pass on their genes to ensure the survival of their own kind. However, the big claw may be a handicap to the males too because it makes them more obvious to their predators, and they cannot use the big claw to feed as it is too big for their mouth. Thus, the females have two equal sized claws as they need to eat double fast to gain more energy for laying eggs which is very energy consuming.
As usual, we saw many Creeper Snails around. There are many of them around probably due to the abundance of food as they feed on algae. Thus, it is important that we walk in a single file whenever we visit the intertidal areas to minimize the damage we do to the life out there.
Sponges are also commonly seen on Semakau. Some may think that Sponges are plants, but they are actually animals! They have pores in them which enable them to suck in water and feed on the tiny particles in the water. In the past, people used the dried sea sponges to clean and to bathe, but nowadays those sponges that we use are mostly synthetic sponges. The sponges have to be processed before they can be used as they contain tiny spikes in them called spicules. It can sting quite badly if you touch them.
There are many Sand-sifting Sea Stars (Archaster typicus) around and some of them are in the pseudo-copulation position. It is said that this position will increase the chances of external fertilization when the males and females release their eggs and sperms into the surrounding water.
Besides the Sand-sifting Sea Star, we also saw quite a few Cushion Stars (Culcita novaeguineae) that day and here are 2 of them! (: Saw the individual in the bottom picture for quite a few times during the past trips and it has definitely grown bigger!
And of course, we have the Knobbly Sea Stars (Protoreaster nodosus)! They are named the Knobblies as they have many knobs on their body, and they also have a hard calcium carbonate skeleton which protects it like an armour from its predators. They can grow really huge and some may even be bigger than the size of our plates! Sea Stars have a water vascular system which acts like the circulatory system in our body. However, the Sea Stars circulates sea water in them instead of blood.
And here's the Sandfish Sea Cucumber (Holothuria scabra). They can burrow very well and similar to the Sea Stars, they have a water vascular system in them too! Some may recognise this as the Sea Cucumber that we have on our plates during Chinese New Year. Although they may be edible, they have to be properly processed first as they contain toxins in them.
We also saw the Stonefish Sea Cucumber (Actinopyga lecanora). This Sea Cucumber has a smooth skin, unlike the Sandfish Sea Cucumber which has a rough skin.
The 3rd Sea Cucumber of the day - the Synaptid Sea Cucumber (Family Synaptidae). They may look like a gigantic worm from far but it is the longest Sea Cucumber. They have very thin body wall that may break apart when they are handled out of water. These sea cucumbers have tentacles that help them feed on tiny organic particles that float around in the sea water.
Our hunter seekers also found us a Flower Crab (Portunus pelagicus) moult! Crabs are crustaceans that moult to grow bigger. When they are moulting, they will pump water into their body so that the new shell that hardens will be slightly larger. Thus, sometimes, when we buy the Crabs from the market, we may think we're paying for a very fleshy crab, but actually we're paying for the water in them if they just moulted not long ago.
One of our participants saw this Snapping Shrimp (Alpheus sp.)along the way. They are usually hard to spot but we always hear them snapping. The Snapping Shrimps have an enlarged pincer that can produce a loud exploding sound to stun their prey like little fishes.
One of the guides found this Starry Bornella (Bornella stellifer). Was quite excited when i saw this as it is my first time seeing this Nudibranch! (:
We also saw this Polka Dot Nudibranch (Jorunna funebris) that we commonly see on Semakau. Nudibranch literally means naked gills. Unlike the fishes which have gills under their gill covers, the Nudibranchs have feathery gills that are exposed on their back. Some of the nudibranches may secrete toxins into the water when they are stressed thus we should not touch them.
Can you spot the Anemone shrimp (Periclimenes brevicarpalis) beside the Anemone? Similar to the Nemo, the Anemone shrimps have a layer of mucus around their body to protect them from the tentacles of the Anemone. The Anemone provides protection and shelter for the shrimp and the shrimp feeds on the leftover food from the Anemone.
As we walked out to the reef, we saw many Corals around, like the Boulder Coral in the picture above. Coral reefs are massive structures that are made of calcium carbonate. The corals are like our HBD buildings which houses many animals. They grow in colonies with lots of little coral animals living inside called the polyps. Although the corals are filter feeders, they also have algae living in them which supply most of the nutrients needed by the corals. In return, the coral provides the algae with protection and carbon dioxide to make food.
Although this may look like an Anemone, it is actually a Hard Coral! This is a Sunflower Mushroom Coral and is named so because it has a stalk that is stuck to a substrate when it is a juvenile and it looks like a mushroom! Also, they have long tentacles that contain stinging cells. Unlike most of the other corals that exist in colonies, this is actually a solitary animal.
Besides the Hard Corals, we also have the Soft Corals! (: This is a beautiful soft coral, which is commonly known as the Dead Men's Fingers. When the tide is high, the tentacles float around in the water and resembles the fingers of humans! x_x Unlike the Hard Corals, the Soft Corals do not have a hard exoskeleton.
People said that good things come in pairs, and we're lucky to see not one, but TWO Tigertail Seahorses (Hippocampus comes)! As the seahorses are very small, they usually use their long tail to wrap around nearby vegetation, like seagrasses, in order not to be swept away by the strong currents. Sometimes, they also like to swim in pairs, with their tails hooked together! Unlike most animals, instead of the mummies who get pregnant, it is the daddies that carry the eggs till they are hatched! The mummies will deposit the eggs into the pouches of the daddies and then he'll fertilize them.
And here's our resident Giant Clam (Tridacna squamosa)! It is amazing to see a Giant Clam in such shallow waters as they are usually found in deeper waters. They are the largest clams in the world and have symbiotic algae living in them which can photosynthesize and shares its food with the clam.
And lastly, we also saw the Spider Conch (Lambis lambis)! It has been some time since i last saw them. They have a very strong foot which allows them to hop around on the shores. The spines on their shells makes them look like spiders, and also help them maintain stability and prevent the snail from toppling over as it hops. Although it is quite large, it is may be very hard to spot as the top side is usually very well camouflaged. However, the underside is still as beautiful as ever and if you look at it closely, you'll be able to see a tiny pair of eyes looking back at you!
Although it was a hot day at Semakau, everyone surely enjoyed themselves! (:
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