At Surface Value
The next time you are at a marina, don’t just admire the vessels on the water. Look also at the pontoons that serve as docks for yachts and small boats!
Besides “housing” boats, pontoons provide shelter for a variety of marine organisms. The submerged sides of pontoons provide homes for immobile life forms near the water’s surface where light can penetrate more easily than at greater depths. The immobile life forms in turn serve as habitat for mobile organisms. Thus, the pontoons create conditions for a variety of marine life to thrive.
The seawalls of marinas are also ideal for the establishment of marine organisms. The cracks and crevices on the seawalls provide stable places for marine plants and animals to attach themselves to and grow.
Find out more about the variety of unique organisms that can be found just beneath the water’s surface in our City in Nature.
Coin Green Seaweed
One of the best-known kinds of surface marine life, seaweed is found throughout our marinas. Green seaweeds, like the species that we consume, can actually be found in a diverse array of forms. While some have soft tissue, others have a more rigid structure due to calcium in their cell walls; some have smooth edges while those of others are serrated. They also come in a variety of shapes, with some even resembling grapes.
It may surprise some to know that species of red seaweed contain chlorophyll and are able to photosynthesise. Compared to their green counterparts, however, red seaweeds contain additional pigments that allow them to be better adapted to lower light levels. Hence, they can be found not only in shallow bright areas near the water’s surface, but also in deeper waters where green seaweeds may not survive.
Soft Like Jelly
Soft corals, as their name suggests, are soft and flexible. Unlike hard corals, they do not have a stony skeleton and this allows them to sway beautifully with the current. When exposed to air, they flop over and often look deceptively like a pile of jelly. In fact, soft corals are relatives of jellyfishes, belonging to the phylum Cnidaria.
The most common soft corals found in our marinas belong to the family Nephtheidae. These
flowery soft corals come in bright colours such as cream, yellow, orange, brown and pink. One such example is the bushy looking soft coral, a species of Dendronephthya. Its vivid pink colour makes it hard to miss as it stands out against the background. What is easier to miss are the small brittle stars or crustaceans that are often found hiding and seeking shelter among its branches!
A wide variety of sponges can be found in our marinas, adding vibrant colours and textures to the otherwise dull-looking pontoons and seawalls. Sponges feed by filtering plankton from the water and, in doing so, improve the water’s clarity.
One of these, Lendenfeldia chondrodes, is a sponge that forms a layer over coral rubble and is often seen on our southern shores. Like icing on a cake, this sponge has a glossy, smooth but rubbery texture. Sometimes it can also exist as irregularly shaped knobs, folds or lobes.
Thumbs-up Sea Squirt
Sea squirts are sedentary organisms that grow on hard surfaces such as the pontoons and seawalls in marinas. Also known as ascidians, they can be solitary or form colonies. Solitary ones, like the Thumbs-up Sea Squirt, look like a thumbs-up sign protruding from the rest of the epibiota (organisms that live on the surface of another one). Colonial ascidians, on the other hand, form smooth mats comprising many small individuals.
Sea squirts are also filter feeders. By drawing water into their body through one of their siphons, they feed by filtering plankton from the water, and then eject the waste through another siphon.
These odd looking blobs may appear to be simple animals but they are actually complex organisms with circulatory and digestive systems. Believe it or not, they are more closely related to humans than to other marine invertebrates (animals without a backbone). For example, one characteristic is that their larvae possess a backbone-like structure that is lost upon maturity.
Frilly Sea Anemone
Sea anemones are close relatives of jellyfishes and corals. They can attach themselves to any hard surface in a marina, such as the sides of pontoons. They can be as small as one centimetre or grow up to as big as two meters, a size that is visible even to an observer on a pontoon.
Sea anemones are carnivorous predators. They capture their prey by using their stinging tentacles to immobilise small animals within their reach. However, as seen in the animated movie Finding Nemo, some of them can be homes for small fishes and shrimps that have developed an immunity to their stings.
Found in our waters are marine flatworms (phylum Platyhelminthes). These are ferocious predators that glide around seeking out unfortunate prey. The marine flatworms range from tiny ones found under rocks to larger specimens that roam about in the open. Some have vibrant colours and patterns while others camouflage well with the background.
Marine flatworms are usually more active in the dark. By undulating the elegant ruffles of their body edges, they are able to “swim” gracefully in the water. No wonder they are called dancing ribbons! Some species of marine flatworms have interesting mating rituals called penis fencing which involves the male flatworm “stabbing” the female with its penis to transfer its sperm!
Can’t get enough? Watch this clip to learn more about the fish you can find in our streams. The enhancement of such ecosystems and conservation of our marine species contribute towards efforts to transform Singapore into our City in Nature.
Learn more about our Nature Conservation Masterplan, particularly the Marine Conservation Action Plan that aims to safeguard marine life and environment. You can also read more about our coastal and marine ecosystem here as well as how you can help out in conservation efforts.
You can contribute by participating in the Plant-A-Coral, Seed-A-Reef Programme, a platform for organisations and individuals to support habitat enhancement efforts at the Sisters’ Islands Marine Park. Visit the Garden City Fund here for more information.
Visit NParksSG, our refreshed YouTube Channel that serves as a one-stop repository for close to 300 video resources. It also provides you a platform for existing and future digital outreach including DIY gardening and related crafts, virtual tours of our green spaces, and livestream events.
If you are heading to our green spaces, do the right thing and be socially responsible. Maintain a safe distance from other park goers and keep to not more than five persons in a group. Always wear a mask except when you are engaged in strenuous exercise or when consuming food, drink or medication.
Do check out the visitorship levels of our parks using our safe distancing portal before you head down and avoid the ones with high visitorship.
For more information about the flora and fauna found in Singapore, please visit NParks Flora and Fauna Web.
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Text by Bryan Wu and Zhang Wei Qing
Photos by NUS Reef Ecology Lab
Certain parts of this article are adapted from Hidden Havens: Exploring Marine Life in Singapore’s Marinas.
A collaboration between NParks and partners at the National University of Singapore, this book brings readers into the hidden world under the sea. Admire the colourful and fascinating creatures showcased and learn about where they can be found. Follow the journey from the submerged surfaces of floating pontoons in marinas, through the water column and to the seafloor. Download the book here www.go.gov.sg/hiddenhavensbook.
About the writers
Bryan Wu is a third year Journalism student from Nanyang Technological University’s Wee Kim Wee School of Communications and Information. As part of his school’s professional internship programme he chose to intern at NParks’ Communications and Community Engagement department. In this time, he has created posts for NParks’ social media platforms, assisted with NParks video productions and written articles for NParksBuzz.
Zhang WeiQing is a Life Sciences graduate from the National University of Singapore. She recently completed her final year internship with the Coastal & Marine Branch of the National Biodiversity Centre in NParks where she was tasked with the planning and running of Intertidal Watch surveys and other events. An animal and marine lover, she chose to specialise in environmental biology for her education and hopes to contribute towards the safeguarding of our marine biodiversity and habitats.
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