Story of a Sea Snail

This used to be the entrance to the home of a type of sea slug called Turbinella pyrum, whose habitat is the shoreline of modern day India [Cf]. The shell used to be covered in a dark, protective layer called periostracum, but this has either decomposed or been removed, and the shell has been thoroughly polished. The color of the shell is white with some faded pink areas, and there are many black dots and scratches due to erosion caused by either processing or grease from human skin. The apex of the spiral has been removed so that it can be used as a trumpet. The cotton handgrip did not originally belong to the shell, but we will dive into that later on.

Turbinella pyrum are part of the genus Turbinella, which have appeared off the Indian coast since Oligocene times, 30 million years ago. Our conch likely belongs to either the globosa or acuta variation, based on the shape and size of the shell. This suggests that it comes from shallow waters off the coast of the southeastern tip of India [Aralarusan et al 2016].

Therefore, our story begins with the birth of a sea snail in the Gulf of Mannar, located between India and Sri Lanka. In shallow waters off the coast our sea snail hatches from an egg at the same time as its hundreds of brothers and sisters. He or she is born with its shell and is as big as the tip of a pencil. Within 12 months it grows up to 6 to 7 centimeters in length, the diameter of the shell being around 3 centimeters. At this stage it feeds mostly on its siblings and algae, but as it gets bigger our sea snail starts feeding on bristle worms [Selvakku 2020, p 770]. It spends most of its life roaming grass beds and sandy sea floors, 4 to 8 meters beneath the surface. At a year and a half of age, having reached maturity, it is ready to mate.

The mating season of the Turbinella pyrum starts in late January and early February. A female, often 1.5 times the size of males, attracts a handful of contenders. All alternately take their turn. The eggs that the female carries are fertilized by the retractable penis of the male [Mahadevan et al 1966, p 216].

Another year later, now 2.5 years of age, our sea snail has grown up to 18 centimeters in length. By now it has less to fear from predators such as crabs and sea turtles. The only main predator of adult conches at this stage are humans. And so, one day, as our unfortunate snail ultimately faces its destiny, it is dragged up to the surface by a conch diver and dies soon after…