Ellisella elongata Pallas, 1766
Sea Whips are Cnidaria, a phylum of marine animals, which often wash ashore on Southern beaches. Sea Whips are shaped a little like tiny leafless trees, though they are often colorful — red, orange, yellow, magenta, purple, turquoise, or white. They can grow to a height of 2 feet.
The phylum Cnidaria is composed of four classes. One of those classes, Anthozoa, includes Sea Whips, Corals, and Anemones. Alcyonaria (or Octocorallia), a subclass of Anthozoa, includes Sea Whips, Sea Fans, and Sea Pansies.
The Sea Whip is covered with spongy “bark” which is living tissue. When the Sea Whip is undisturbed, it expands small white polyps from around the stem (“trunk,” to continue the tree analogy) and the branches. These polyps feed on tiny organisms in the water. When the polyps are retracted, their positions are evident from small slits on the surface of the Sea Whip. When a Sea Whip is found on the beach, the polyps are retracted.
The Sea Whip has a strong internal skeleton made of proteinaceous material. In dead specimens the hard core, or “axial rod,” resembles a brown or black wire. Dead colonies of wire-like Sea Whips are sometimes coated with a gray, translucent, rigid jelly-like material which is actually a bryozoan (moss animal), Alcyonidium hauffi; or white, calcareous encrusted bryozoan Membranipora arborescens.
Incidentally, if you collect a colorful Sea Whip on the beach, you should probably let it air outside for two weeks, because polyps die when exposed to the air and give off a dead-fish odor.
Sea Whips often live in colonies. The animals usually attach themselves with a protein holdfast (“root”) to hard surfaces like oyster reefs or rock jetties. They may also grow on the bottom in tidal creeks and sounds. The springy branches of the Whip sway with the currents.
Sea Whips are home or host to various sea creatures. The Atlantic Winged Oyster often attaches itself to a Sea Whip branch. Certain species of barnacles, shrimp, snails, and sea slugs may live on a Sea Whip, and some may eat the host's tissue.
In the Southeast coastal area, there are three species of Sea Whips.