A Date with Mumbai’s Marine Wildlife

It’s a Sunday Funday of a different kind. We are a motley group gathered on Mumbai’s Juhu Beach, garbed in hats, sunglasses, gumboots, and shoes. It’s a purposeful lot, brimming with anticipation and questions. The truth is, we have all been to Juhu Beach before. It’s a beach that has many a reputation: of being heavily polluted, of being a crowded immersion site, of being home to a dizzying array of street food, and even being a coveted make-out spot.

One February Sunday, we are there to uncover a new side to this beach, to explore its marine wildlife. No, not the selfie-clicking kind.

If the collective Marine Life of Mumbai (MLOM) is to be believed, there’s a treasure trove of wildlife to be spotted along the city’s coast. We just have to look for it. “These animals are really tiny, so it is difficult to sight them. But, once you start, you will see them all around you,” says marine biologist Gaurav Patil.

Patil is leading a shore walk, as part of the Coastwise 2020 festival. The event is a collaborative effort between MLOM, WWF India, and the Mangrove Foundation of Maharashtra.

MLOM just completed three years of educating and informing people about the coastal biodiversity and habitats in the urban environs of Mumbai. In these three years, they’ve seen changes — in the animal diversity, their personalities, and in the shore too.  They’ve also become well versed with what to expect and where to find it.

To begin, we get handy little booklets entitled, Common Shore Life of Mumbai. It’s a colourful user-friendly guide to help spot marine animals. Our shore walk doesn’t need the books because we have real-life guides, Patil, Pradip Patade, one of the founding members of MLOM, and Caroline Pais of WWF India.

Our walk begins at the water line, at which point most people are already regretting not wearing appropriate footwear (pro tip: sneakers don’t help). With the previous night being a full moon night, today’s low tide is at the lowest point possible. The area where the ocean meets the land between the high and low tide forms the intertidal zone, itself divided into three parts – upper, middle, and lower. Patil explains that the animals in the upper zone are more resilient to temperature, wind, and increase in salinity than those in the lower zone. Being the city known for its “spirit”, we can only guess that its marine wildlife is abundant in resilient upper tidal zone creatures.

Proof of this is the decorator worm. Patade spots it and gathers us around. The worm gets its moniker from using whatever it can find around it as a solid decorative shield. “It’s an indicator of pollution,” he says pointing out how the worm has used plastic and other rubbish to “decorate” itself. “In Goa, they attach coconut husks and seashells to themselves. The worm secretes a parchment tube and attracts materials from the surroundings to camouflage itself. It lives underground.” The trick to spotting this worm through its brilliant camouflage is to look for the opening of the tube. “These polychaete worms have many legs. When tides rise, the entire structure is erect and forms a miniature reef that creates a shelter for smaller creatures. It’s essentially attracting its prey,” adds Patade. It’s essentially a well-disguised scavenger.

Another scavenger is the marine snail. This tiny creature, faster in movement than its terrestrial counterpart, has muscular feet and leaves a trail behind. Though tiny, it’s a predator that feeds on creatures its own size. Immediately, there’s a clamour of questions: how can something so tiny feed on something as big as itself? Patil smiles at our confusion. “The general rule of terrestrial wildlife isn’t applicable here.”

The commonest creatures we suddenly spot everywhere are snails. Babylonia are orange in colour with patchy markings in a spiral. They are found in the region below the sub-tidal and rarely surface. Indothais have spikes or protrusions on their body. Patil says if you cut a snail in half, it reveals a series of chambers. As the snail grows, it closes one chamber and occupies the outermost one. Their shells have a chalky lid that they can “lock” to protect their body inside. As snails have to keep their body moist at all times and reduce water evaporation, they sometimes huddle together on rocks. Spiral melongena are large snails found on the shore that migrate to a rocky surface to lay eggs. They lay thousands of eggs in zipper-like capsules. It’s common to find these white capsules lining rocky surfaces.

As newbies to the marine world, the only creatures we can spot easily are mollusca, soft-bodied invertebrates with a shell made of calcium carbonate. Beyond the plain ones, we spy a brilliant purple-and-white lined one called sunset siliqua, named because of the “rays” on its back. The shells remain closed when alive, the dead ones are found scattered on the sand. Pais tells us it’s a bad idea to collect these seashells or even discarded conches. “The shells are made of calcium carbonate. Animals collect calcium carbonate from the sea and synthesise it into shells. Once they die, the shells are used by other organisms or disintegrate, and the calcium carbonate goes back into the sea,” she says.

Her advice is accompanied by a warning. “The conus are sea snails with intricately patterned shells. If alive, it is venomous and able to kill humans with a single sting,” adds Patade, showing us a dead shell. Cone snails are built to kill and paralyse their prey before eating them; only the fish-eating snails are harmful to humans. The shells are pretty to look at but, I can almost sense the group make a collective resolution to not touch shells anymore.

Another good piece of advice is to avoid eating oysters in Mumbai and big cities. “Oysters and clams may accidentally consume pollutants from the sea and store it in their bodies. When you eat it, these get passed on to you and are harmful to your body,” says Patil, even as we admire the vibrant white shells of the oysters on the rocks.

These discarded shells are also prime real estate, for creatures like the hermit crab. It is the hermit crab that embodies the true “spirit of Mumbai”. They have soft abdomens with no protective cover and carry discarded snail shells, replete with calcium and iron sourced from the water, to protect themselves. If they don’t find shells, they use other trash available on the shore. When they outgrow their shells, they find larger ones and often fight and kill for them. We spot hermit crabs in different snail shells, and even one recently victorious specimen, scurrying along, dragging its new trophy.

The stories we hear aren’t all about resilience and adapting to changing shores. There are diseased anemones, dying because of lack of oxygen. Anemones are multi-cellular organisms that hunt using their tentacles. Patade points out a spotted swimming crab, missing its claws. These crabs don’t belong to the sandy shore, but are brought in by fisherman’s nets and then discarded. These crabs are pelagic – live in open waters – and often don’t survive on the shore. Swimming crabs are distinguished by their last pair of legs, which are flat like paddles.

As we walk along the waterline, the sand suddenly appears to be teeming with creatures. There are snails leaving trails everywhere and we gingerly step around them and the anemones and hermit crabs hiding in shells. A tiny blob in the sand reveals itself to be a jellyfish, which glows when disturbed. “At night, when crashing waves break, you can sometimes see lines of them glowing,” says Patil. Elsewhere, we spot a beautiful porcelain crab, belonging to the squat lobster group. Its tail is folded and if threatened, it will lose its arms and legs and regrow them. Another resilient creature is the octopus. “When handled, they can sense our hormones, and change their behaviour, body texture, and colour, accordingly,” says Patil. For a creature that changes colour, it can only see black and white.

Over on the rocks, exposed because of the low tide, we find sponges — brown, purple, and green in colour. They look like moss, but have open pores and are soft to touch. “They’re filter feeders that suck in water through small pores, and shoot it out from the bigger ones. They usually get washed off in the monsoons,” says Patil. As we move along, he lifts rocks to reveal the various species that have made it their home.

The word spoken at the beginning of the class suddenly make sense. Now that we’ve learned to identify these creatures, we suddenly spot them everywhere. From stomping on the sand, we have now become careful, gingerly stepping on the sand to avoid crushing mollusc, snails or sea anemones beneath our feet. The tide pools are home to many creatures – colourful sponges clinging to rocks, pearly white oyster shells, shy octupuses hiding as soon as they sense us, and snapping crab. If we look closely, we can spot jets of water spurting in the air.

“The beach has suddenly come alive,” says one of the participants. We nod in agreement.