Tag Archives: Mollusc

Kellet’s Whelk: Meat-Loving Mollusc

When thinking of marine predators, snails aren’t usually the first animals that come to mind. The Kellet’s whelk is a type of carnivorous sea snail that lives in the sandy bottoms and kelp forests of the California coast, and inside its beautiful spiral shell lie a host of finely-tuned predatory tools and instincts. The Kellet’s whelk is the largest whelk species in California, growing up to seven inches in length. Its life span is unknown, but some scientists speculate they could live to be up to 50 years old. It spends its days scouring for meat on the ocean floor, either by scavenging on dead animals or by hunting sea snails, clams, and crustaceans. Like many other gastropods, whelks have sensitive chemoreceptors that allow them to “taste” the water for dissolved particles, helping them find food from a distance. A dead fish carcass will often attract several whelks from all over the ocean floor.

Kellet’s whelks hunt by using a long, muscular proboscis, which is a flexible appendage kind of like an elephant’s trunk. At the tip of the proboscis is a rough radula that acts as a file to grind away pieces of meat and shell. The Kellet’s whelk can extend its proboscis to over twice its body length, so it is able to reach food from a distance even if it lies in rock crevices that are two tight for its body to fit. If it is hunting another snail, the whelk will secrete digestive enzymes as it grinds a hole in the shell so it can suck out the body of the snail inside.

In recent years, a growing demand for Kellet’s whelk meat has turned it into a rising fishery, with most being taken as bycatch in lobster traps and sold to fish markets. Because the Kellet’s whelk is slow to grow and mature, they are vulnerable to being over harvested, and new research is being conducted to measure the ongoing effect that these new fishing practices will have on the whelk’s population levels.

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Written by: Megan Petkovic

Insided Look: California Sea Hare

Don’t get confused by the name, California sea hares are actually a type of sea slug commonly found in intertidal zones along the coast of California and Mexico. Their color depends on the food they eat. One of their favorite foods is the red algae plocamium, which is what gives many of them a pinkish-red color, but others can appear more brown. This helps the sea hare blend into their environment, and they will usually spend most of their time hiding in intertidal seaweed. Sea hares accumulate toxins from the algae they eat and store them in their body, making them distasteful to most predators. When attacked, California sea hares will expel a bright purple ink, which is mildly toxic to some animals.

Though sea hares like to live in shallower waters, they cannot move around outside of the water like other intertidal creatures. Their soft bodies are supported by a hydrostatic skeleton, which is a system of fluid-filled cavities surrounded by muscle. When the sea hare moves, it changes shape by flexing these muscles and pushing the fluid in different directions. This only works because the pressure of the fluid inside the sea hare’s body is equal to the pressure of the water outside it. Outside of water, this system breaks down, and the sea hare turns into a shapeless, immobile lump.

Sea hares have been compared to rabbits since ancient times because of the ear-like structures on top of their heads. These are actually chemical receptors called rhinophores, which the sea hare uses to detect dissolved chemicals in the water. This helps it locate food and track down the pheromone secretions of other sea hares. Sea hares are hermaphrodites, which means they possess both male and female parts. Once one or more potential mates are found, they will sometimes form daisy chains, which is a line of slugs all mating at once.

It is hard not to fall in love with the sea hare. Their squishy bodies and bunny-like appearance make them very charismatic representatives of the amazing creatures we can find in the intertidal zone. Next time you go tidepooling, take a peak in the seaweed and see if you can find one of these camouflaged algae-lovers. Just make sure you keep that hydrostatic skeleton intact and leave it in its watery home.

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Hello Bunny…I mean Sea Hare!

Written by: Megan Petkovic

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