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Tide-pooling for starters

The world of wonders that lie underwater

Low tide zone in a tide pool. (Source: Wikimedia Commons)

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I’ve lived in coastal cities (Chennai and Mumbai) for 20 years, vacation often in Goa and have always loved the beach. But until I was sent Sejal Mehta’s sparkling gem of a book, Superpowers on the Shore (Penguin, 2022) to review, I had no idea of what I had been missing right under my nose all this time — the vast intertidal zone that was exposed when the tides retreated. So, on this trip to Goa I decided to make amends and walk hawk-eyed among the rock pools shimmering in the retreating tide and see what treasures lay in wait to be discovered.

The first thing that caught my eye were little bubbles in the wet sand appearing everywhere when a wave retreated. And then just a glimpse of what were tiny pearl-white crabs: they knew a heavy-footed newbie was around and with a disdainful shimmer buried themselves under. Everywhere there were little balls of sand arranged in tasteful rangoli-like patterns. Hmm…it was time to start pestering Sejal about who were responsible for these. Turns out it was the work of sand-bubbler crabs (what a wonderful name!) and their relatives, soldier crabs. Soldier crabs would take in small globs of sand, mumble at them, filtering out all the microscopic goodness, leaving neat little balls of sand tastefully arranged on the sand.

Then, I approached the exposed rocks themselves: my sense of balance is not to be trusted so I dared not clamber over them – they were armed with razor-sharp barnacles that could lacerate you like a cheese-grater.

Barnacles, incidentally, superglue themselves upside down onto rock surfaces – and anywhere suitable, including the hulls of ships – and look like little volcanoes. When a wave washes over, a slit appears on the top as do two legs with which it takes in whatever it can snag, the slit shutting tight when the wave withdraws.

Splattered everywhere were also what looked like bird droppings: some were dry, others shone with a mother-of-pearl sheen. It was apparently just possible that they were oysters that the fishers had divested of all pearls!

Slowly, I got my eye in, occasionally being distracted by, and trying to sneak up to, a Kentish plover (not really meant to be here at this time of year) darting over the rocks and cocking its head at me inquiringly. A furtive movement caught my eye: there it was, a crab in rock-camouflage colours, then another and another. They seemed to sense they were under scrutiny, for they quickly snuck into dark niches in the rocks, a pair even plopping into a rock pool and swimming briskly across it before disappearing. These were possibly swimming crabs, though I didn’t see the flippers they were supposed to have. A dead fish, maybe six inches long, floated past in the rock pool and I could see the shadow of a crab sneak out from its submerged hideout and try to reel it in. The crabs could have really thrown the mother of all parties with that fish, but it was let go of quite quickly. (Not fresh enough maybe?) Other little fish with large anxious eyes twisted and turned speedily after one another in the pools.

Also in the crevasses of the rocks were clusters of grey and white carunculated snails, as secretive as conspirators, whispering bad things about the government. Each snail is both a he and a she, and the he of one snail makes out with the she of another and vice versa. With some species, a he can turn into a she!

Just under the level of the water in one pool, I spotted a pale flower-like creature, with delicate white chrysanthemum-like petals: Anemone! Sejal responded enthusiastically. There are hordes of different kinds and those flowery petals were usually poison-tipped tentacles which they waved around and caught their prey with.

Strewn across the sand were tiny white butterfly shells, and, occasionally, a larger one with an attractive wavy pattern sketched over it. A heap of really tiny scallop-like shells clustered over what seemed to have once been a crab. Meet one, eat one, eh?

But what really made my day was the tiny hermit crab I met, tucked away in a shell that looked like a spiral cone very like the old swirly ice-cream cones of yore. Curiously, I picked it up and the resident peeked out of the entrance before hastily ducking back in.

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Hermit crabs have a wonderful (if often fractious) living arrangement. They accommodate themselves in the discarded shells of other creatures like snails. But they keep growing, and so, need newer larger quarters every so often. So, they squeeze out of their old homes and go in search of more commodious accommodation. Outside, there are others waiting to claim this newly vacated property and ready to fight for it, if necessary, though some queue up like polite Britishers waiting for a bus.