First guided walk at Pulau Hantu - 2 Apr 2010

My first public walk of the year was at Pulau Hantu. My group consists of participants who were not new to intertidal walks as they have joined us on walks at Pulau Semakau previously. Their enthusiasm and interest in nature made guiding very much enjoyable!

The island is actually made up of two islets: Pulau Hantu Besar (Big Ghost Island) and Pulau Hantu Kechil (Little Ghost Island), and is aptly named as "island of ghosts". It was here that 2 great ancient Malay warriors dueled fiercely to their death. The gods then transformed the two warriors into islets and their ghosts are said to wander the isle.

Warriors wannabes?

Despite its proximity to the Pulau Bukom's refineries, a wide variety of corals can be found on Pulau Hantu coupled with fairly rich marine life. Our first star (pun not intended) of the day was the Sand-sifting Sea Star (Archaster typicus). These 2 individuals had a few shorter arms probably chomped off by predators. Although they can regenerate their arms, it is a long process and I would imagine it to be quite an unpleasant experience.

We were thrilled by the male Fiddler Crab's (Uca spp.) morning greetings. It was really quite a spectacular sight to see them waving their enlarged claw, as if playing the fiddler. Not sure if it was the mating season, but they sure were eager to capture attention. We even saw 2 fighting each other, likely for territory or a mate. The enlarged claw is a great asset in courtship, as females are likely to be attracted to those with larger claws since it is quite a feat to be able to survive with this 'liability' which requires more to maintain.

 

The Hairy Crab (Pilumnus vespertilio) attracted praises of  'so cuuuute' as it hid in one corner of the container. Also fondly known as the Teddybear crab to some, the Hairy crab got its common name from its appearance. The hairs fluff up when the crab in water thus breaking its outline and results in some really good camouflaging performance. Note that this is not the Hairy Crab some Chinese deem as a delicacy, in fact, this crab is mildly poisonous.

The Orange Striped Hermit Crab (Clibanarius infraspinatus) was quite shy that day, and there wasnt time to wait for a nice photo opportunity. Unlike real crabs, the hermit crab actually has a soft abdomen thus requires the protection of an empty shell as its home. So, think twice when you next think of collecting an empty shell from the shore 'cos you may be depriving our friend of its potential home.

My guests laughed when I asked if the Black-lipped Conch (Strombus urceus) reminded them of a woman's lips with black lipstick. Like other Conches, the Black-lipped Conch also uses its operculum to hop along the surface.

The Spider Conch (Lambis lambis) is named so, after the spikes on the sides of its thick shell, resembling the legs of a spider. The conch's humble appearance makes it difficult to spot among its home, but turn it over, you will be awed by its pretty shell, just like many of our participants were. Apart from being a master of camouflage, the Spider Conch is a great pole vaulter with the use of its knife-life operculum to hope along the surface.

This is a probably a Wandering Cowrie (Cypraea errones) strolling around, 'feeling' and 'tasting' the water with its siphons. This snail is a great master at maintain its looks. See the shiny and smooth shell without scars and scratches, all thanks to its intelligence use of its own mantle to cover its shell. While I have all praises for the cowrie, I wish its shell wasnt as pretty to prevent it from being a victim of over-collection.

 

Nudibranches never fails to fascinate me with their bright colours. 'Nudi' is translated as naked in Latin and 'Branchia' as gills. The Nudibranch's naked gills (see the feathery structures) is thus what gave its name. This sea slug actually possesses a shell when young, but sheds it thereafter. It thus develops defense mechanisms such as bad tasting glands, and depicts the poison through its bright colours to warn predators.

Heres the pretty Chomodoris lineolata.

   

The colours of the Black Margined Nudibranch (Glossodoris atromarginata) were also fascinating.

   

While the Phyllid Nudibranch (Phyllidiella pustulosa) may look puny and cute, it is actually deadly to other marine life. Try placing this nudibranch in an aquarium , stress it and the entire tank could be wiped out by the milky substance it secretes. This is typical of its family which feeds on poisonous sponges, and concentrate the toxin in its tissues as a defense mechanism.

    

An animal that many people can recognise at first sight, the Jellyfish (Chrysaora sp.) can sometimes be seen at our popular beaches at Changi or East Coast. One should avoid touching one though, because of its stinging tentacles. A friend had complained of discomfort after being stung by a jellyfish during her swimming lap of a biathlon.

   

Giving us the Puss-in-boots looks was this Octopus (Order Octopoda), known to us as one of the smartest invertebrates that can recognise its tracks and even open the lids of jars. Another master of camouflage, it can change its colour and even texture of skin to match that of its surrounding within the snap of the finger, all thanks to special pigment cells.

My favourite of the trip was this Red Feather Star (Class Crinoidea), although it reminded me of the feather duster my mum used to cane me with. Although it has a mouth in the middle of its top surface, the Feather Star feeds by filtering small particles of food from the sea water with their feeding feathery arms. Like other echinoderms, the Feather Star has a symmetry of 5 - this individual apparently has 25 arms (go on, count it!).

Right beside the Feather Star was a humble looking (and therefore very well camouflaged) Onch slug (Family Onchididae) that I did not spot, if not for Ruixiang's obvious hint. Breathing through simplified lungs, this slug is more related to land snails and slugs. Its often seen on the surface of rocks as it is where it finds algae, its source of food. Without a hardy shell, the Onch slug secretes a supposed bad tasting mucus that covers its skin to ward off predators.

An intertidal trip is always precious and never possible for one to see everything. Apart from having to abide by the rules of the changing tides, our marine life roams freely and is thus never predictable. Such is nature, but this also make every experience special and unique. Come explore our shores and sign up for the next available trip! 

First intertidal walk of 2010!

I was a zombie on Pulau Hantu (pun not intended - hantu means ghost in Malay) on New Year's day, with little sleep the night before, and after a strenuous badminton game that morning. Nonetheless, it was all worthwhile for my first encounter with the seahorse (yes... after 1 yr in the intertidal area...), and a photo of the utterflyfish.

We arrived at our destination after an hour-long boat ride. The skies were getting a little dark, and we were getting a weeeee bit worried but tried to be as optimistic about the weather as we can.

After a short briefing, we headed towards the intertidal area but end up racing back to the hut some 2 minutes later because it started pouring! Thankfully the rain stopped after an hour else the trip will be in vain.

We started our recce which was conducted in preparation of the public walks in 2010. After walking past the mangroves, we reached the intertidal area and I was greeted by (my guess) the inspiration of Spongbob Square Pants - Sponges!

Sponges are actually animals and not plants, despite its appearance. They are the simplest form of animal with no respiratory or circulation system, and feeds by filter feeding ie they pump water in and out of itself and pick up edible particles.

Interestingly, this is also the sponge that we use at home, or rather, used to use at home. Nowadays, we use synthetic sponges now instead of real dried sea sponges.

Sexy lips, aren't they? =P This is the Black-Lipped Conch (Strombus urceus) and is easily recognisd by the black border around the edges of the shell's underside. This is yet another animal that is vulnerable on our shores, due to the loss of habitat because of our land reclamation & development, and also due to over collection of its shell.

I didn't see as many Sand-sifting Sea Star (Archaster typicus) as I did on Semakau, but still managed to capture a phone of one. This Sea Star burrows into and sifts the sand, thus its name. They move with their tube feet, which also helps to bring food to its mouth, both found on its underside.

One of the more exciting sighting on the trip was this Red Egg Crab (Atergatis integerrimus). I've never seen the full view of one before. It was hiding under rocks (and therefore partially hidden) the last few times I chanced upon it. Looking red and succulent, some people might mistake it as a delicious delicacy, just like the chilli crabs that some people are in love with. Rule of thumb in the animal kingdom: Bright colours, avoid. This is in fact a highly poisonous crab, in fact, the toxins can't be rid of even after cooking.

In a tidal pool, the Bohol Nudibranch (Discodoris boholiensis) was showing us its elegant slow dance moves. Named after the exposed breathing gills found at the back of its body (Nudibranch = naked gills in latin), Nudibranchs are sea slugs with shells when young. Interestingly they lose their shells as they grow older, and develop other defense mechanisms such as toxic or bad tasting glands, and warns predators with their bright colours.

As we walked on, we were greeted by iterally, a sea of Sargassum. This is probably the most common brown algae on rocky shores, and are easily recognised by the air-filled bladders that keeps the plant body afloat. Algae (also called Seaweed) have no roots, fruits nor flowers, and are usually of a consistent colour.

While we are likely to find lots of animals beneath the Sargassum since it provides good shelter, we were treading really carefully for fear of stepping on something that we really shouldn't be, or don't want to (eg like Stonefish!).
 

Indeed, a volunteer spotted an animal that was maybe seeking solace among the seaweed. My first time meeting Mrs Tigertail Seahorse (Hippocampus comes), named after the its tiger-like rings on its tail. This is probably a female as it does not have a pouch. The envy of some ladies, the male seahorse shoulders the responsibility of carrying the eggs, placed by the females in their pouch. Apparently, these sea horses are normally found in pairs so not sure whether its buddy went into hiding. Although the Seahorse does not look like it, it is actually a fish! But, without scales and it swims upright instead of horizontally!

(Again) Another endangered animal (again) due to habitat destruction. In addition, its also used for traditional Chinese medicine, resulting in over fishing.

At the corner of my eye, I saw a flash of orange, which disappeared the minute I turned in its direction. Suspecting that its the Butterflyfish (Chelmon rostratus*) , I stood motionless, hoping to prove myself right, and I was! If you thought that the black dot is the eye of the fish, then you would have been fooled, just like the Butterflyfish's predators. It is said that the butterflyfish uses the false eyespots to create an impression of a head at the wrong end, thus misleading predator in attacking the less vital body areas. Sometimes, the predator may completely misses the butterflyfish with a wrong plan of attack.

Unfortunately these beautiful fishes are popular in the live aquarium trade although I'm sure they would very much prefer their freedom in the open sea.

 

I was surprised that this Swimming Crab (Thalamita danae) did not showed its usual aggressive stance when I approached it. It merely moved its pincer a little when it sensed my presence. As the name suggests, its a really good swimmer thanks to its last pair of paddle-like legs.

Although we were stranded for an hour, we were lucky to have some time to explore the area. Looking forward to sharing the wonders of the intertidal area at Pulau Hantu!