These must really migrate because we found two of these while diving in Cozumel last week!
They are kind of creepy looking given the fact they resemble a spinal cord.
Mating and egg laying occur during the spring and fall migration. Internally fertilized eggs are surrounded by a transparent mass of albumen, a gel-like material, and are laid in protective flat, rounded egg capsules joined to form a paper-like chain of egg cases, also known as a “Mermaid’s Necklace”.
On average each capsule contains 0-99 eggs, with most strings having 40-160 capsules. After laying their egg cases, female knobbed whelk will bury one end of the egg case into the substrate, thus providing an anchor for the developing fertilized eggs and preventing the string of egg cases from washing ashore where it would dehydrate. Fertilized eggs emerge as juvenile knobbed whelks approximately .15” (4 mm) in length.
Knobbed whelks are native to the North Atlantic coast of North America from Cape Cod, Massachusetts to northern Florida. This species is common along the Georgian coast. It is the state shell of New Jersey and Georgia.
Knobbed Whelk Shells
The knobbed whelk lives sub tidally and is migratory, alternating between deep or shallow water, depending on the time of year.
During the weather extremes of the summer and winter months, these sea snails live in deep water, at depths of up to 157’ (48 m). In the milder weather of the spring and fall they live in shallow water, on near-shore or intertidal mud flats and sand flats.
In the shallow-water mud flats whelk prey on oysters, clams, and other marine bivalves. They wedge a bivalve open by inserting the edge of their shell, and insert their long proboscis to eat the flesh of their victim. They rasp at the flesh using their rough tongue-like organ that has thousands of tiny tooth-like protrusions.
One of the many reasons scuba diving is so fascinating!