Some students dread a test, while others are happy to take one.
Perhaps it depends on the location of said test. Tests taken in a classroom are surely more stressful than the ones found on a beach. Last week, 10-year-old Clyde Smith came across a test in Menemsha. It was not the typical paper and pencil, fill-in-the-circle variety nor was it an essay. It was the test, or outer skeleton, of a sea urchin.
Sea urchins are the hedgehogs of the sea. With their round hard bodies covered in spines, they easily live up to that nickname. It may be a surprise to learn that sea urchins are related to sea stars and sand dollars — until you take a more scholarly approach.
If you are lucky enough to find a sea urchin and examine it up close, take note of the shell, or more accurately, outer skeleton. After the animal dies, its spines fall off and the test is what is left. The test has five plates of one design and five of another — 10 in total. It is the pattern of fives, called pentamerism, which demonstrates the urchin’s relation to sea stars and sand dollars. All of these animals are categorized as Echinoderms, which is translated from Greek as “spiny skin.”
It might be another kind of test to make heads or tails of sea urchins. How do you tell the top from the bottom? The bottom surface has a five-part beak-like mouth with self-sharpening teeth. These crunchers can even chew through stone!
In the History of Animals, Aristotle explains the physiology of the sea urchin, “the urchin has what we mainly call its head and mouth down below, and a place for the issue of the residuum up above. The urchin has, also, five hollow teeth inside, and in the middle of these teeth a fleshy substance serving the office of a tongue. Next to this comes the esophagus, and then the stomach, divided into five parts, and filled with excretion, all the five parts uniting at the anal vent, where the shell is perforated for an outlet. ... In reality the mouth-apparatus of the urchin is continuous from one end to the other, but to outward appearance it is not so, but looks like a horn lantern with the panes of horn left out.”
The mouth on the bottom or oral surface is called Aristotle’s lantern, as it resembled the lamps of his time. Algae, mussels and other invertebrates are the food of the sea urchin. In turn, the urchin can be a meal for lobsters, crabs and other hungry sea dwellers, or a desirable delicacy for us.
Many cultures eat sea urchins; however, there is only one part of the animal that can be consumed. Forget the sharp spines or the hard test and go for the gonads. The roe is the favored food that is reputed to be tasty and useful as an aphrodisiac. Famous eater of all things Euell Gibbons explained, “the sea urchin has no flesh that I can discover, so only the roe or gonads are eaten, and they taste even more delicious and delicate than even the finest caviar.”
Two varieties of sea urchins are the most common ones found in our waters, the green sea urchin and the Atlantic purple sea urchin, and we are currently within their harvest season. While it may be a trial to find enough roe for a feast, if you do, it might be the best taste test you’ll ever know!
Clyde wasn’t likely to be interested in eating his find, how many 10-year-olds could be convinced to eat that sort of thing? It is more probable that his test won’t end up with the others on the refrigerator with a gold star, but will take its place among his most treasured possessions — those that are sure to stand the test of time.
Suzan Bellincampi is director of the Felix Neck Wildlife Sanctuary in Edgartown, and author of Martha’s Vineyard: A Field Guide to Island Nature.
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