It wasn’t a bonk on the head that had me seeing stars. Nor was it a figment of my imagination. It was a giant sea star spreading its plump arms across the sandy bottom of the saltwater tank. It surprised me both in appearance and magnitude. While it is not uncommon for the saltwater aquarium at Felix Neck to have a variety of animals, it is unusual for someone to sneak in an addition that large without me noticing.

But there it was, wrapping its arms lovingly, or more likely menacingly, around a clam. For the clam, it was the beginning of the end. Sea stars are known for their powerful arms that have a vascular system of tube feet, which can force open even the heartiest bivalve. A sea star can exert an immense amount of pressure that will overcome a shellfish’s ability to remain closed.

Opening their dinner is only the first step. Sea stars don’t eat in, they only eat out. With a stomach capable of “eversion,” the sea star can put its stomach inside out. Once on the outside of its body, the stomach goes to the inside of the shellfish, where it will consume it in situ, actually liquefying the bivalve and digesting the contents before the sea star returns its stomach to the inside of its body. No jaw or teeth needed for this animal.

Sea stars are excellent eaters, known for their voracious feasting on shellfish, often to the shellfisher’s chagrin. Various reports give insight into the sea stars’ conspicuous consumption. One sea star can eat 50 young clams or seven oysters per day. In a single study held over a six-day period, all this eating allowed the sea star to grow more than 300 per cent. No wonder the shellfishers are concerned. 

Because of the sea stars’ enjoyment of the bounties of the ocean, they once had bounties on themselves. Cash payments were offered in both Massachusetts and Rhode Island for sea stars. 

During the Depression, a bushel of sea stars could get you 50 cents! Farmers were happy to have them ground up for fertilizer. And in 1929, one oyster company in Rhode Island removed more than 10 million sea stars from 11,000 acres of oyster beds in Narragansett Bay. J. G. Woods, a British naturalist, rightly observed, “The starfish is one of the most mischievous of creatures in an oyster bed, many thousands of the inmates falling victims to it every year.”

Sea stars are extraordinary not only for their appetite. Like the scarecrow in The Wizard of Oz, they might lament, “If I only had a brain.” This simple invertebrate has not a brain, head or even blood, but can regenerate limbs or itself from a single limb.

Salt water acts as its blood, entering through the madreporite, a spot (yellow or orange) on the top of this animal and spreading through its vascular system. Even without a brain, sea stars can sense light, temperatures, orientation and touch.

Surely, though, the most unique accomplishment of the sea star is its ability to regenerate itself. At one time, cutting these animals in half was a method to try to reduce their populations, but it was quickly realized that instead of limiting the population with this method, the result was a doubling of the population! A sea star can regenerate from one arm or even a piece of an arm. Needless to say, this makes the species of enduring interest to scientists. Submerging sea stars in hot water to kill them quickly replaced the earlier method, and was met with much more success.

A few varieties of sea stars can be found on the Island. In Sengekontacket, purple brittle sea stars can be seen. But for the traditional larger, five-armed common sea star, try exploring under the docks at Menemsha at low tide.

And resist the urge to call them starfish, as they are definitely not fish, since they lack gills, scales and a backbone. 

They are, however, always the star of the show. Even when they show up unexpectedly in one’s aquarium, they bestow on the Island its justly-earned reputation as a playground of the stars.

Suzan Bellincampi is director of the Felix Neck Wildlife Sanctuary in Edgartown, and author of Martha’s Vineyard: A Field Guide to Island Nature.