At low tide, a handful of people—couples, adventurers, and lately marine life enthusiasts—can often be seen clambering out on the rocks near Haji Ali. When they arrive at the farthest edge, they usually find they’ve been beaten to it. Fisherwomen are here already, digging out

to sell across the city.

The oyster women have long known what Mumbaikars have only recently begun to discover: the rocky shores of Haji Ali and Worli are teeming with diverse and productive life.

More than 350 marine species have been identified on the city’s intertidal zone—the area submerged at high tide—in recent years, thanks largely to volunteer group Marine Life of Mumbai (MLOM). At least 36 can be found on the Worli stretch, according to a study by Sagarshakti, including corals protected under the Wildlife Protection Act. The denizens include: snapping shrimp, clapping crab, Asian green mussels, eels, and sea sponge, which recent research suggests were among the first animals in the world.

All of them will vanish under the

road, including the oyster beds. As Sagarshakti’s report notes, creatures dependent on the nexus of air and water cannot survive burial by non-oceanic mud and concrete. Corals and

cannot be relocated like tigers.

Hints of this life are abundant during low tide at Haji Ali. Sand is brushed with the trails of sea snails. Rocks are speckled white with their eggs. Barnacles make clambering over the jagged shore easy but falls blistering. Algae slips and slides underfooot. At one end, squirts of water hit you as if little people were hiding underground with tiny water-guns. They are molluscs or bivalves, explains MLOM’s Shaunak Modi, creatures that live under sand or rock, taking in nutrients from the water before shooting it back out through siphons.

Closer inspection reveals a complex and varied society, not unlike our own. Each species does its best to survive in this polluted urban ecosystem. The male fiddler crab waves its one gigantic arm to attract females (in Japan, says Modi, they are known as “the ones who beckon the waves”). The deceptively fragile sea anemone, with its translucent tentacles, is a predator that grabs any passing plankton. Coral and algae strike a symbiotic deal: coral provides shelter; algae reciprocates with colour and energy.

And what appears to be bits of tangled string and rubbish on the sandy patches turn out to be decorator worms. The worm produces a cement to build a protective tube around itself, usually from shells. But on this city’s shores, the tube is also woven with bits of plastic wrap. A true Mumbaikar.

These creatures dwell permanently at the junction of water and land. Others come and go. They arrive from the sea to shelter or breed. Eggs and baby fish are found in the intertidal area, even the occasional octopus. A study by the Collective for Spatial Alternatives notes that while the shallow seas comprise only 8% of the ocean, they are the most productive part.

The shore’s tiny creatures provide food and income for artisanal fishing communities. A recent survey by the Central Marine Fisheries Research Institute found that reclamation would likely destroy the livelihood of the women who collect oysters here. Those who pick clams, crabs, and even lobsters, will also be affected.

The shoreline is often seen as only a transit from land to ocean, an in-between place of no importance. Fisherwomen like Ira, who routinely comes from Trombay to Haji Ali to dig out oysters to sell at Rs 800 a pail, know better. It’s a hidden world of riches – perhaps soon to be a lost world.