With a population of four million, an exceedingly urbanised landscape, and the busiest port in the world, not many would expect that the waters off Singapore are able to support any marine life that is of interest. Motivated by the threats of coastal development and a lack of awareness, a group of volunteers, known simply as The Hantu Bloggers, have been working tirelessly for the past seven years to shed some light on the diversity of marine life that can be uncovered in the nooks and crannies of one of Singapore’s most popular reefs, Pulau Hantu.
(Left) The Blue dragon nudibranch (Pteraeolidia ianthina) is commonly found on the sandy seabed or upon rocks along Pulau Hantu’s reef. Although those encountered were mostly blue, this sea slug reportedly comes in various colours from yellow to green. It is identified by the purple bands on its long oral tentacles. What’s fascinating about the Blue dragon nudibranch is its ability to capture zooxanthellae and store these within its body. Zooxanthellae are microscopic plants that live in the tissues of animals. Here, the zooxanthellae get protection and in turn provides the nudibranch with much of the nutrients produced through photosynthesis.
Text by Debby Ng. Photos by Jimmy Goh
Pulau Hantu, Malay for “Ghost Island”, is located just 13 kilometers from Singapore’s city center. It was once a home for hundreds of coastal villagers, and a rest stop for coastal birds, until it was developed in the 1980s for high-end tourism. Although much of the original mangrove forest and coral reef was destroyed in the development process, organisms have recolonised the reclaimed areas over the past 20 years. Today, much marine life remains to be discovered in its small and shallow reefs.
Left: Carpet eel blennies (Congrogadus subducens) are extremely shy, and tend to slip away before they are noticed. This one however was very curious and swam out from the safety of the coral to greet the photographer. Often mistaken for a snake or an eel, the Carpet eel blenny is actually a harmless fish that is commonly found on Singapore shores, hidden among coral rubble or near seagrasses.
Gobies are abundant on many of our shores. But they are hard to spot. At the slightest sign of danger, they bolt into burrows or dart under rocks. Even in plain sight, they blend in with the sand and mud. Several of them reside in burrows dug into the sandy seabed or along reef slopes.
Blue-spotted fantail rays (Taeniura lymma) are commonly found in the reefs of Pulau Hantu. They are usually found hiding under corals or large boulders. They are rarely found buried under sand. The ray moves into shallow sandy areas with the rising tide to forage for snails and clams, worms, shrimps and crabs. This beautiful ray is under pressure from over-collection for the aquarium trade and destruction of its reef habitat. It is considered near threatened.
This rare and brilliant nudibranch was recently spotted at Pulau Hantu as it was feeding on a colony of hydroids. Hydroids are colonies of tiny stinging jellies, best described as hundreds of inverted jellyfish attached to a feather- or seaweed-like base. They are in fact, related to jellyfish. Hydroids grow on boulders and coral rubble, and are often overlooked as it resembles a plant.
Filefish are commonly found throughout Singapore’s waters, but this amazing Feathery filefish (Chaetodermis penicilligerus) is a little more special. It is distinguished from other filefish by thick feathery extensions all over its body including the dorsal spine. It has dark stripes along the sides of the body, sometimes with short bright blue lines. The fish may be greenish, bluish or purplish. It is also commonly known as the prickly, tasselled or leafy filefish.
The Snakey bornella (Bornella anguilla) is a beautiful nudibranch has a very characteristic mosaic-like colour pattern. Its name (anguilla = eel) refers to its method of swimming. While most species of Bornella can swim by flexing their bodies laterally, generates a muscular wave that travels down its body to produce an eel-like motion. It is a relatively large species of Bornella, growing up to 80mm, and is just one of the many beautiful species of sea slugs that can be found at Pulau Hantu.
The Tigertail seahorse (Hippocampus comes) is one of the mascots of Pulau Hantu’s reef. This individual is still a juvenile and has yet to develop its brilliant adult colours and stripes that are its namesake. Seahorses can be found throughout Singapore’s coast, and can even be spotted along its major beaches during low tides. This little one was spotted “running about” in the open sandy bottom. Seahorses are the slowest fish in the ocean.
Sawtooth Shrimp (Tozeuma sp.) were first spotted on Pulau Hantu’s reef by The Hantu Bloggers in 2003. Though they are found throughout the Indo-Pacific, these shrimp are rare in Singapore and little is known about them. These beautiful and cryptic shrimp hides by clinging onto Whip corals or Black corals, and blending in with the thin “fronds” by swaying along with the current.
The Striped Fang Blenny is also referred to as Gammistes Blenny, Striped Blenny, or Striped Poison-Fang Blenny. It has alternating black and yellow stripes that run the entire length of the body. This individual has made a home out of a discarded glass bottle on the reef. These shy fish usually hide in cracks or funnel like structures on the reef, retreating into the safety of their home tail first, which allows them to peek out at passing divers.
The dazzling colours of the Yellow shrimp goby (Cryptocentrus cinctus) stand out against the monotonous colours of the seabed. The pelvic fins of this fish are fused into a disc, which helps keep the goby propped up as it rests on the seabed. This individual shares a burrow with an alpheid (pistol) shrimp. The shrimp, which has poor eyesight, relies on the goby’s good vision to be alerted to danger. In return for this favour, the shrimp works hard to maintain the structure of the burrow. It is very tricky to photograph the two together as they usually dart into the depths of the burrow if so much as a shadow of a diver is seen.
Hypselodoris bullocki is a species of beautiful nudibranch that never fails to delight divers. Its bright colours are a warning to predators that it is best left alone. This sea slug feeds on venomous hydroids, ingests the toxins and stores it in its body to be used as a defense against predators. The slug in this picture is laying a bright yellow-coloured ribbon of eggs. The word “nudibranch” is Latin for “naked gills”. The flower-like appendage on the back of this sea slug are its gills. Some species are able to retract their gills into their abdomen at the sense of danger.
The Slender Ceratosoma (Ceratosoma gracillimum) is one of the brilliant nudibranchs that can be seen in in Singapore waters throughout the year. This sea slug allegedly “hardens” when it senses danger. It is distinguished from other sea slugs by its well-developed lateral lobes on each side, just in front of the gills. It can grow up to about 12cm in length. These sea slugs notably feed on sponges and incidentally resembles the appearance of its prey.
This fish with a flat head and a delicate fringe over its eyes is commonly seen on many of our shores, in sandy and coral rubble areas near reefs. The Fringe-eyed flathead (Cymbacephalus nematophthalmus) is a stealthy fish that hides in the cover of the sand and waits patiently for passing prey.
Cuttlefish are amazing animals that are seasonally common on many of Singapore’s shores. Although better known as seafood, these delightful creatures are equally delicious to observe, with their colour changes, busy behaviour and curious demeanour. Like squid, cuttlefish squirt a jet of water out of a funnel while they zoom off in the opposite direction. They can move in any direction, but move fastest backwards. Cuttlefish can hover or swim slowly by undulating the fins along the sides of its body. Squid do not have this all-round fin. Instead, squid have a triangular flap at the tip of their bodies, which act as stabilisers. Though cuttelfish are more active at night, they can still be spotted during the daytime by The Hantu Blog’s keen-eyed and experienced volunteers.