At times, finding shells on the beaches of Hilton Head can be a bit difficult.
One of the most coveted shells to find is that of a whelk. They are the beautiful conical shaped shells that we hold to our ears to hear the ocean. While there are four varietal species that can be found in our waters, the knobbed whelk is the most abundant.
Knobbed whelks, Busycon carica, are large predatory gastropods. They are large sea snails that can vary in color, size and features depending on their distribution along the coast. They have been found in both tidal estuaries and deeper waters of the Atlantic coast. Knobbed whelks are distributed from Cape Cod all the way through Florida and have been found in depths of up to 150 feet, but tend to stay in more shallow waters. They prefer to live in sandy or muddy bottoms and can be found congregated on oyster and clam beds. Knobbed whelks have very little long shore movement, but have been known to travel to deeper waters because of water temperature and breeding. During winter storms they are known to bury themselves and go dormant until the weather gets better.
Knobbed whelks can reach up to nine inches in length.
They grow by extending their shell around a central axis. When looking at a whelk, the very top peak of the shell is where the creature began. From the top whelks creates turns (known as whorls) as they evolve. The final whorl becomes the largest and is known as the body whorl. This is the area that creates the opening that the snail withdraws into. Knobbed whelks are identified by low knobs found on the shoulders of the whorl. Their withdrawing aperture is on the right hand side. They can range in color from light orange or yellow all the way to brick red.
Knob length, color and size can all be determined by the specific habitat along the Atlantic coast that the whelk lives in. Diet and natural camouflage are all factors that cause differences in shells. All whelks have a hard horny plate known as an operculum. This acts as a protective cover for the snail when it retreats into its shell and protects it from predators. This plate is also referred to as the shoe. The operculum is attached to the whelks foot, which is its appendage that protrudes from the aperture and is used for transportation.
Whelks are carnivorous.
They use both their shell, as well as an appendage known as a radula to eat other hard shell creatures. Whelks will use the lip of their shell to chip at and pry open hard clams and oysters. Once a whelk is able to pry open another bivalve, they use their strong radula to tear away strips of tissue for consumption. At times eating food causes damage to the whelks shell. Using the lip of their aperture causes chipping and damage, in which they must take time to repair instead of to grow. This is a large factor in the fact that whelks grow very slowly.
Knobbed whelks are protandric hermaphrodites, which means that they start their life as males and turn into females as they get older. Female whelks will lay eggs twice a year usually when the water temperatures are around 68 Fahrenheit. September to October is their most productive time, while April to May also has substantial yield.
They create egg strings that have a series of coin-shaped capsules attached at one end by a rough cord or string-like structure. They can reach lengths of up to one foot. The first capsule of a string does not usually contain eggs. This is the part that the whelk buries in the ocean floor to act as an anchor as the eggs develop. Strings may have up to 120 capsules, each containing up to 35 eggs. The eggs will hatch within their capsules anywhere between three to 13 months.
By Kathleen McMenamin, Master Naturalist