Walking the Intertidal Zone

If you want to see some of Singapore’s wonderful sea creatures without diving under the water, your best bet is to head over to Changi Beach Park just around low tide.

That great flat morass of seaweed, sand, and water is part of the intertidal zone (technically, any shore area between the low and high tide marks). Changi Beach Park 6 is a particularly great place to explore the intertidal zone because there’s an unusually long, flat stretch of barely-submerged beach at low tide (you’ll find more tips at the bottom of this post).

There’s so much to see here if you don’t mind getting your hands and feet wet (but please don’t take any animals home or touch them unless you know it’s safe). Let’s take a look at what I found on two recent visits.

Sea Cucumbers

Most people wouldn’t say that sea cucumbers are very sexy, but I love that they come in such a wide variety of shapes and colors. And they’re all over the place! The ones below include pink warty, sea apple, thorny, orange, and smooth varieties.

If you’re patient, you may even see them put their feeding tentacles out:

Watching a sea cucumber move around can be a truly wonderful (or eerie, or gross, depending on your perspective) experience.

Egg Casings

Again, not usually considered a sexy category, but eggs and the things that hold them can be pretty amazing. Take the structure above, which is what the volute shell uses to house its eggs. Then there’s this creation …

… which the moon snail makes as a combination of mucus, sand, and teeny tiny eggs. One collar can contain thousands of eggs.

The tiny purple and beige fringes below are the egg capsules of the elegant drill shell:

Sea Anemones, Sea Pens, and Jellyfish

Rather amazingly, sea pens (above), anemones, and jellyfish are related to each other (they’re all members of phylum cnidaria). Sean pens usually stick upright in the sand, but you might find them lying flat in the intertidal zone. And if you flip them over, you’ll likely find tiny porcelain crabs living within their polyp leaves:

You might also encounter jellyfish as part of an intertidal walk, though finding a live one isn’t especially common. We were lucky to see this mangrove jellyfish, which had just been freed from a fisherman’s net:

There are plenty of anemones at low tide — watch your step — including carpet anemones and what I think is a common cerianthid.

Sea Stars, Sand Dollars, & Sea Urchins


Sea stars, sand dollars, and sea urchins are all echinoderms (as are sea cucumbers), generally known for their five-point radial symmetry. I think this one is a cake sea star:

Closely related to sea stars are brittle stars, whose legs seem to break off all the time (don’t worry — they grow back).

You may find sea urchin shells with a few legs still attached, or you may find just the husks of their bodies:

Sand dollars — both alive and not so — are plentiful at low tide:

Sea Squirts

Believe it or not, these are our closest invertebrate relatives — apparently, we share similar hearts and nervous systems (and 80% of our genes). Sea squirts are a pretty common sighting along the shores, often attached to sponges.

Crabs & Hermit Crabs

Crabs move quickly, so unless you’re an excellent photographer, you’re mostly likely to find the shells of recently-deceased critters. The flower moon crab is particularly attractive:

It’s much easier to find (and hold) live hermit crabs. Not true crabs (but related, albeit somewhat distantly), hermit crabs move into all different kinds of shells for housing:

We also saw a large cluster of them being very active and wondered what was going on.

Snails & Shells

There are lots of shells on the beaches of Singapore, the largest of which generally include mussels and a wide variety of clams (that’s a fan clam above).

If you’re lucky, you may also find a noble volute snail:

Sponges

Sponges are all over the place along the intertidal zone, sometimes floating freely and sometimes attached to rock formations.

Sponges often support other life forms, including worms, sea squirts, and brittle stars:

Blobs

What is this? A blob is obviously not the name of any kind of intertidal species — it is just something that neither Google nor I have been able to identify. If anyone knows what these things are, could you please leave a comment?

How-Tos

Where to go: Changi Beach Park 6 is your best option. You can also try Changi Beach Park 7, Pasir Ris Beach Park, Coney Island, or St. John’s Island.

When to go: The best time to head out is shortly before low tide (there’s better visibility as the tide is going out than when it’s coming in).

What to bring: Shoes with sturdy bottoms (so you don’t have your foot punctured by a stonefish), mosquito repellant (Changi Beach Park has some monster mozzies), a flashlight (if you’re doing an early morning or evening walk), a plastic bag (to keep your phone dry), sunblock, and a water bottle

Who to go with: You can walk around on your own, of course, but if you want to see and learn a whole lot more, I would recommend that you go with a guide. I took my first trip with Untamed Paths.

Identifying animals: The wildsingapore website is a great help in trying to figure out what you’ve seen.

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