A sea whip looks much like a colorful, leafless plant that’s been cast up on the beach.
Actually it’s the remains of a branching colony of miniscule animals called polyps.
Worldwide there are about 500 species of sea whips, which belong to a group of marine invertebrates called soft corals. They’re related to the hard or “stony” corals that make up coral reefs. More distant cousins include jellyfish and sea anemones.
In a live sea whip, the polyps are arranged in rows along the sides of the colony’s “trunk” and “branches.” Each polyp has a soft, whitish, cylindrical body with a mouth and eight delicate tentacles. When active, the polyp emerges from a slit-like opening and extends its tentacles to ensnare protozoans, tiny crustaceans, and other microscopic food items adrift in the surrounding saltwater.
Sea whips live underwater attached to rocks or other substrates via a disk-like holdfast. They lack the rigid calcium carbonate skeleton characteristic of stony corals. Instead, they’re strengthened by an internal, wire-like support system that’s strong but flexible, allowing them to sway back and forth with the currents.
Sea whips help to provide habitat for snapper, grouper, and other fish. Also, a diverse assemblage of small mollusks, crustaceans, and other organisms may live directly on or attached to their branches.
Strong storms sometimes dislodge sea whips from their moorings, washing them ashore. A common species on South Carolina beaches is the aptly named colorful sea whip (Leptogorgia virgulata), which averages eight inches long and ranges in color from pink and magenta to yellow, red, and orange.
Vicky McMillan, a retired biologist formerly at Colgate University,lives on Hilton Head Island. She can be reached at email@example.com.