One of the nature activities that I personally enjoy the most, intertidal walks, may actually be a foreign concept to many – so if you don’t know exactly what they are right now, fret not and just keep reading to find out!
The “tide” in “intertidal”, as you may have guessed, is a reference to the tides of the sea. These are walks done on beaches during low tide, during day or night, where one wanders around anticipating the discoveries of fascinating marine life that are otherwise inconspicuous. Another reason for the nomenclature is the specific zone at which these walks happen, the intertidal zone. Intertidal, or littoral, zones exist on every coastline, the piece of seabed linked to the beach which is submerged during high tides and exposed when the tide recedes. Water levels are generally low, with a relatively shallow depth of water even during higher tides. Spring tides, which are the highest and lowest tides, demarcate the start and the end of the intertidal zone.
Biodiversity varies vastly even within the intertidal zone itself. Differing tide levels equate to fluctuating submersion times and thus exposure to oxygen and sunlight, with areas further from the beachline increasingly submerged. Chances of tides low enough to expose that region of land thus also are more limited. These factors in turn influence physical and chemical parameters which results in the segregation of organisms along the intertidal zone, dependent upon their capacity to survive and thrive in the specific conditions of that area. This zonation distribution across the elevation gradient, of both aquatic flora and fauna, is one of the interesting things you will be able to observe during your own intertidal walks, with a visualization shown below.
Distribution of biodiversity in the intertidal zone (Source: Pearson)
The type of biomes where one can gain the intertidal experience also diverge. Other than the sandy shores that most of us think of, there are also really interesting areas like rocky shores, seagrass beds and even mangrove swamps! Each are different in how they support life, with rocky shores having more tide pools that hold enough water to support organisms that cannot typically survive in exposed low tide conditions, and sandy beaches with its softer substrate allowing for more burrowing to escape continuous exposure and take a respite from the heat of the boiling sun. In Singapore, sandy beaches are the dominant type, while rocky shores are limited to the areas of Labrador Nature Park and Tanjong Rimau in Sentosa. Seagrass beds can be found at some areas of Changi Beach and Pasir Ris Park, and the Chek Jawa Wetlands is a famous intertidal hotspot that is the intersection point of 6 different habitats. Therefore, the Singapore coastlines are actually really diverse and are wonderful places to explore!
We’ve been talking about this intertidal zone a lot and some of the things you can expect, but how does one actually do an intertidal walk? Well, it’s much simpler than you’d expect! Intertidal zones are generally accessible, being mostly located at beaches that are open to the general public. However, take note that some areas like Labrador are nature reserves and thus protected and closed off, or require prior signups for access through guided tours. Chek Jawa is an example of the latter – so if you want to experience the unique wetlands for yourself, be sure to keep an eye out for NParks’ guided tours (they fill up fast)!
Other than these specific places, it is entirely possible for you to go on intertidal walks yourself, with your family, or with friends. Just remember to check tide tables (can be found on NEA’s website) for the specific days and timings where tides are low (the lower the better; try for 0.5 and below) so that your visit will coincide with the periods where tides have receded enough to expose more of the intertidal zone for optimal exploration. If you’re just starting out and is feeling uncertain, or want a more scientific and educational experience, check out Young Nautilus! They specialize in guided walks (with a focus on intertidal) and have wonderful friendly guides who will bring you on either public or private walks where you will be exposed to the world of the marine, complete with all the fun facts and scientific knowledge you need! Remember to change into appropriate footwear like water booties so that you can walk around with a minimal risk of slipping or cutting your feet on rocks or corals. Other forms of protection like hats, sunscreen and gloves are also encouraged.
Once geared up, it’s time to begin! Finding cool creatures is easier than one may think. A huge diversity of aquatic life is hidden in plain sight, just waiting for people to keep their eyes peeled and spot them while they go around their usual activities. Just by staying alert and having a sharp eye, one can spot a plethora of organisms that are always there but never taken note of previously. When you see something, always try not to touch it without knowing what it is, both for the animal and for your own safety as some can be venomous or dangerous.
It’s that easy! Go out there, look for things, and take cool pictures to record your finds! Some examples from my own walks are included below, just to give you a picture of what you can expect to find.
Orange-striped hermit crab at Changi Beach
Pink warty sea cucumber at Changi Beach
Ghost crab at Changi Beach
Lined chromodoris nudibranch at Tanjong Rimau
Hope you find these as cool as I do! They are a mix of some of the more common organisms and some slightly harder to find ones, but these are only the tip of the iceberg. There is an entire world to explore out there and a multitude of creatures in all shapes and sizes just waiting to be discovered – so pull on your booties and go on an intertidal walk!
Written by: Estella