Discovering Our Seas – The Amazing North Coasts of Singapore

May 19, 2023
Neo Xiaoyun

Growing up, my dreams of the sea included scenes of Atlantica (from Disney’s The Little Mermaid). When I went to the beach in Singapore, I was disappointed in comparison. Thus began years of distancing myself from the sea, because I associated seas/coastlines in Singapore as lifeless places, where the waters were dull brown/olive green (instead of turquoise/aquamarine/green/light blue), waves lacklustre, with brown/grey sand that was coarse to the touch. In fact, there is a lot of marine wildlife in Singapore if only we know where to look!

I started walking along the Northern shores of Changi Beach for intertidal explorations with like-minded friends in Jan 2020. Treading carefully, life seemed to teem everywhere we looked— seagrass, crabs, shrimp, clams, fish, stars, urchins. We were moving from tide pool to tide pool, identifying between different species of sea stars, clams and crabs. Innocuous enough – this walking between sand, sea and sky. Little did I know: this would be the start of my long and still ongoing journey of environmental, cultural – and even emotional – reconnection to the sea.

My favourite intertidal explorations are pre-dawn explorations. In the words of Elton John, there’s a calm surrender to the rush of day. With the stars twinkling above and the moon reflecting on the water’s surface, I relish the palpable sense of freshness of a new day mixed into the brine of the sea breeze.

Initially, I was almost biodiversity-illiterate. Thumbs-up sea squirts, sea cucumbers, ascidians, anemones, corals, polychaetes, basically all the ‘non-charismatic’ marine life… looked alien to me. Slowly, curiosity overtook apathy. The more I learnt, the more I wanted to know.

Diversity abound

Despite being a teeny island just half-marathon across from north to south, I notice that our southern shores, for instance St John’s Island, Sentosa and Pulau Hantu, somewhat have a different intertidal biodiversity from our northern shores like Pasir Ris and Changi. I find different species of octopi, sea stars, anemones, sea cucumbers… and the list goes on.

This is because the two environments face different pressures: our northern shores face Johor, and are heavily influenced by the 50km-long Johor River which injects a ton of freshwater from Peninsula Malaysia. This means that our northern shores are less saline and more loaded with nutrients, and some marine creatures thrive in these conditions:

The eight-armed Luidia (luidia maculata) is an active and predatory sea star. They move quicker and usually bury themselves in the sand using their ‘combs’ (sharp edges) which can be found along their arms. Sea stars themselves are predators and they use their tube feet to source for clams.
Not much is known about the biscuit sea star (goniodiscaster scaber) due to limited research. This photo is interesting, however, as it captures the ability of sea stars to regenerate their arms. Sea stars would shed their arms as a means of defence. They take some time to regenerate lost or damaged arms — so beware of stressing a sea star unnecessarily.
The slender seagrass octopus is sometimes found among seagrasses on North shores. They have a deep purplish tinge and rather long arms. The octopus above was hardly bigger than a seagrass blade, which reminds us that intertidal environments serve as “nurseries” for the young of many creatures, a haven where they can hide from predators while also hunting for prey such as crustaceans and stranded fish among the tidal pools.
Carpet anemones are unassuming, yet fascinating. In their bodies, they shelter symbiotic algae known as zooxanthellae that photosynthesise and make food for their carpet anemone host. To diversify its nutrition, carpet anemones also possess tentacles that shoot stinging cells into little critters near it, paralysing them before moving them to her mouth. I’ve seen anemones swallowing various animals, sometimes even large ones like crabs! Its body column is able to expand accordingly to consume large meals.
The garlic bread sea cucumber (Holothuria scabra) is a loaf-shaped sea cucumber commonly seen in seagrass meadows of our Northern shores, and occasionally in the south. It gathers and feeds on detritus. Studies have found that sea cucumbers play an important role in the health of seagrasses—by eating sediments and burrowing, it facilitates and enables the nutrient cycle for seagrass growth. Harvesting sea cucumber (called trepang in Malay) is an age-old practice in coastal regions of the world from Madagascar and Malaysia to the Philippines. However, the consumer demand for sea cucumbers has led to overcollection and drastic reductions in population numbers.
The bobtail squid (Sepiolidae) belongs to a group of squids that tend to be found close to the sea bed, in sandy or muddy habitats where they lie buried and camouflaged during the day. They use their tiny rounded fins to bury themselves, and flick soft substrate and sand over themselves. At night, they come out to hunt for small prey such as shrimp. While I’ve spotted one bobtail squid in Pulau Hantu, they are often more found on the Northern shores.
Mactra clams are often seen on our Northern shores, preferring the silt, sand and seagrass. About 7cm long, it has a short siphon for filter feeding particles in the water column. Sometimes the mactra lies buried beneath the surface with only its siphon sticking out. It has a long foot that can elongate outside its body and be used as a “pole vault” to escape from predatory snails such as moon snails and noble volutes.

This is the first of a two-part series that introduces marine biodiversity typically and commonly found on the Northern Shores of Singapore. Check out part two to learn more about marine biodiversity at the Southern Shores here!