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To Whelk or Not

By Mia Davidson and  Jan Sattler
By Mia Davidson and Jan Sattler

Occasionally one comes upon a particularly large white spiral shell deposited on the beach or in the tidepools. This beautiful shell is the hard protective covering of the largest gastropod (snail) found in Laguna, the Kellet’s Whelk (Kelletia kelletii). Capable of reaching a maximum of seven inches in length, the shell is a graceful spindle shape, heavy with knobs around its spiraling whorls. Although the natural color of the shell itself is beige with light brown lines similar to tree rings, it is usually found either white, having been buffed clean by the surf, or with a variety of algae and other marine organisms encrusted on the shell that are often purple, pink and green. The body of the whelk is bright yellow and when retracted into the shell, becomes sealed behind a brown operculum (trap door). The operculum is an oval shaped keratin-like structure that blocks the entrance of the shell and protects the enclosed animal.

Kellet’s Whelks are voracious carnivores that actively hunt and feed on a variety of turban snails, bivalves, barnacles and worms. To consume food, they use a prehensile proboscis tipped with a radula (rasping tongue). Able to extend the proboscis up to three times the length of its shell, it is used to suck in the tissue that the radula has scraped off the victims. They are also scavengers and it is not unusual to find several individuals feeding on a single dead carcass. Rarely found living in the tidepools, the Kellet’s Whelk lives in the subtidal zone throughout the kelp forests, on the rocks and on the sandy bottom up to 230 feet. Originally native only to south of Point Conception, in the last several decades, the marine invertebrate has been migrating north and is now considered to have a geographic range from Monterey Bay, California, to Isla Asunción, Baja California Sur.

Although the growth rates and lifespan of the Kellet’s Whelk is unknown, they are slow growing and some scientists postulate that the largest of them are over 50 years old. From birth, the Kellet’s Whelks have separate sexes. Thought to become sexually mature at approximately 2.5 inches and reproducing annually, they aggregate in groups during March through July to mate. After the male transfers the sperm into the female’s mantle cavity, the female proceeds to deposit clusters of fertilized oval egg capsules containing hundreds of eggs on rocks and other hard substrates. After about a month, in June through September, larvae emerge and enter the water column for about 60 days before settling.

Like other slow moving marine invertebrates, the Kellet’s Whelk is vulnerable to pollution, ocean acidification and climate change. Predators include the octopus, moon snails, sea otters, horn sharks and a variety of sea stars including the locally observed Giant Pink Sea Star. In addition, harvesting of the Kellet’s Whelk for human consumption has radically increased since the early 1990s and there is concern that the species is vulnerable to overexploitation. In Laguna, the Kellet’s Whelk is protected and no collecting of live specimens or shells is allowed.

 

Mia Davidson and artist Jan Sattler are long-time Laguna residents and year round ocean swimmers who believe that educating the public about the marine environment will contribute to preservation of the habitat and its organisms.

 

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