To commemorate International Day for Biological Diversity on 22 May, ISTS brings you another edition of Weird, Wild, Wonderful!
Singapore’s marine life is more diverse than you might think – and many can be easily found at our numerous beaches and reefs. This article introduces just a tiny fraction of the amazing creatures found on Singapore’s shores, showcasing the stranger and more beautiful representatives from the major marine animal groups.
To locate Singapore’s numerous pulau (islands), terumbu (reefs), and beting (shelfs), you can use this map of Singapore waters. Most of these intertidal areas are open to public, though the most accessible intertidal areas to visit are at our mainland beaches (Changi, East Coast Park), and at Sentosa (Tanjong Rimau).
Many of these creatures are revealed during spring tides when the moon is either new or full, so do check the tide timings on NEA’s website before planning your visit!
Cnidaria
Coral, sea anemones and jellyfish are all cnidarians. Cnidaria are a group of organisms with stinging cells that shoot out tiny harpoons, mainly used for catching prey or as defense against threats.
A majestic view of plate-like coral at Kusu Island. These hard corals (Scleractinia) form stone-like structures in which they live. 
This nightmarish creature can be found at a few of our beaches, including Pasir Ris beach. It is actually a sea anemone (Actinostephanus haeckeli) reputed to have a very nasty sting; do not touch it! 
Sea fans (Gorgonacea) found at Marina at Keppel Bay. Like their name suggests, Sea fans build fan-like structures, which often host other creatures like snails and brittle stars.
Clams (Bivalvia)
Clams have two shells, e.g. cockles, oysters and scallops. Some live buried in the sand, others attach themselves to rock, and some even swim.
A file clam (Limidae) with its bizarre collection of tentacles, found at Sisters Island. Some file clams can swim by clapping their shells together, pushing water in one direction while propelling themselves in the opposite direction. 
A giant clam (Tridacna sp.) with a beautiful blue mantle found at Pulau Semakau. Giant clams are essentially very large cockles. They carry photosynthetic organisms (zooxanthellae) in the fleshy flaps (mantle) that line the opening of their shells.
Gastropoda
Snails and slugs are a diverse group of organisms found in a wide variety of habitats. Snails are gastropods with a single shell, while slugs do not have a visible shell. Nudibranchs are some of the most beautiful slugs found in the oceans.
A sea hare (Anaspidea) found at Pasir Ris beach. Sea hares are some of the largest and strangest looking slugs found on our shores. They do have shells, though reduced and hidden under their skin. 
A Bornella nudibranch (Bornella stellifer) found at Cyrene Reef. They are also found at many of our reefs and beaches including Sisters Island and East Coast beach. They have two rows of finger-like projections on their body, where their gills are found. 
A Blue Dragon nudibranch (Pteraeolidia ianthina). These beautiful creatures are found at various intertidal areas around Singapore, including Beting Bronok where this individual was photographed. Blue dragon nudibranchs carry photosynthetic organisms (zooxanthellae) in the projections (cerata) on their bodies. 
A tiny ovulid snail (Ovulidae) found on a sea fan at Changi Beach. Some ovulid snails have shells that look like spinning spindles and are also called spindle cowries. Ovulid snails live on other organisms like sea fans and soft coral, feeding on the polyps of their host. 
A majestic bailer snail (Melo melo) seen on Beting Bronok. These huge snails (20 cm long shells) feed on other snails, using their large foot to enclose their prey.
Decapoda
Crustaceans, such as shrimp, prawns and crabs belong to a group of organisms called Decapoda, meaning ten (deca) legs (poda). They however have more than ten appendages, used for feeding, gripping things, walking, and swimming.
Echinodermata
Echinoderms, such as sea stars, feather stars, brittle stars, sea cucumbers, and sea urchins have radial symmetry, usually five-fold.
A knobbly sea star (Protoreaster nodosus) on the beach at Pulau Semakau. Though large and scary looking, these sea stars are not venomous. They eat a variety of things including algal films, detritus, sessile organisms like sponges and soft coral, and gastropods. 
A feather star (Comatulida) sitting on a bed of cnidarians (Zoantharia) at Sisters Island. We can sometimes see tiny creatures like crabs, shrimp, worms, and brittle stars living on feather stars. 
A basket star (Euryalidae) found at Sisters Island. Basket stars belong to the same group of animals as the more commonly seen brittle stars. They have fractal-like arms that branch repeatedly. 
A pink sea cucumber spotted at East Coast beach, with its mouthparts extended for filter-feeding (right). Sea cucumbers are move along the ocean floor on their tube feet. Some can expel their internal body parts as a defensive behavior when threatened. 
A stranger variety of sea urchin found at Pulau Hantu. Shaped like hearts, they are commonly called heart urchins. They are often completely buried in the sand.
Cephalopoda
Squids, octopuses and cuttlefish are known for having tentacles, the ability to change color and skin texture, and releasing ink as a defense mechanism. More often encountered as food, these creatures are actually very beautiful when alive.
Fish
Fish are probably the most well-recognised of marine animals. Singapore is home to some very strange looking fish!
To learn more about Singapore’s shore life, a good place to start would be WildSingapore, which archives a vast record of our intertidal biodiversity. The website also includes a photo index for easy identification of the wildlife you might spot.
Due to our location, Singapore supports diverse marine habitats capable of hosting such a rich variety of intertidal wildlife. Our warm waters and sheltered coasts are suitable for key habitats like mangroves, seagrass and coral.
As a global shipping hub and whose 25% of land area has been reclaimed, the marine wildlife in our small island is particularly vulnerable. So, in your next trip to our coasts, do respect these nature spaces as wildlife habitats and only leave your footprints behind!
Written by James Koh and Kow Zi Shan
Photos by Loh Kok Sheng
Illustrations by Jia Qi
Your photos are simply impressive. Thanks for sharing! I am thrilled to learn more about Singapore’s marine life!