Sea Pork (Aphlidium constellatum Verrill, 1871)

Sea Pork
Aphlidium constellatum Verrill, 1871

Sea Pork:
Brainy, Briny Zooid

By Patricia B. Mitchell.

When you encounter a glistening piece of Sea Pork washed up on the beach, you might think that you are seeing an internal organ of some type of whale or porpoise or something. It looks like body tissue — a brain, perhaps….

It is actually a firm glob of cellulose housing tiny zooids. The zooids are miniscule in size and have sack-like bodies. When alive, Sea Pork zooids are red, and are arranged in regular, almost circular groups in their protective sheath. The cellulose “tunic” of their compound colony is pink.

When the zooids die, they pop out, and the remaining glob of Sea Pork bleaches to white or gray. Those are often the colors of the Sea Pork you find on the beach. The Pork is cast ashore by storms and surf. The glob is usually 1-4 inches in diameter.

Sea Pork is a subtidal species. It may grow on rock jetties, wharves, corals, and seaweed. The colonies form when Sea Pork zooids group together and encase themselves with digested cellulose derived from the seawater. Some colonies may cover a yard or more of substratum.

Bottom-dwelling fish, skates, and sharks like to eat living Sea Pork.

Sea Pork is grouped scientifically into the class Ascidiacea, which means “a leather bottle.” The odd-looking hunk of Sea Pork, which some people think resembles a piece of salt pork or fatback, has two external openings. These openings are located near each other, though one functions as a mouth and the other as an anus. The zooid colony derives food from the seawater which it pumps through its system.

The zooid reproduces by cross-fertilization with its neighbors, even though the animal is hermaphroditic. The “babies” created when sperm and eggs unite look strangely like tadpoles.

There are approximately 1000 different species of ascidians worldwide.


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