What are Sea Pansies?

Sea pansies are fleshy, leaf-shaped colonies of marine organisms that belong to the genus Renilla, which is in the same Cnidaria phylum as jellyfish and corals. In fact, they are not a flower, but are actually a type of soft coral known as Pennatulacea. They are considered aggregate organisms, which is a colony made up of numerous individuals.

Colonies of sea pansies consist of stalks formed by large organisms called primary polyps, which can be up to 2 inches (5.08 cm) in diameter. These primary polyps have a fleshy structure called a peduncle that extends from the bottom of the main colony. The peduncle thrusts itself in the sand to anchor the pansies to the ocean floor.

The pansy-like body that gives the sea pansies their name is actually made up of various types of smaller, secondary polyps. Some of these secondary polyps are responsible for feeding the pansy. These feeding polyps extend above the sand and secrete sticky mucus to snare any tiny zooplankton and organic matter that venture nearby. Each feeding polyp sends its food to a common digestive system so the entire colony feasts or starves together.

Small white dots are located in between the feeding polyps. These light specks are a specialized polyp that acts as a kind of water pump or outlet valve that deflates and inflates the entire colony. This comes in handy when the sea pansy is threatened by a predator or gets stuck on a sand bar at low tide.

Sea pansies have stalks that are red, blue or purple and studded with brilliant white polyps. Sea pansies are strikingly bioluminescent when they are touched or attacked by a predator. This bioluminescence is caused by Green Fluorescent Protein (GFP). This protein generates bright green waves of light that pulse outward from the point of contact. These pulses of light often help to distract the potential predator.

These unusual creatures are typically found in the warmer areas of the Pacific and Atlantic coasts and are sometimes referred to as "Atlantic coral." These organisms begin begin life as planktonic larvae that all hatch from the same egg. All of the polyps are clones of one another. As the sea pansy matures, it moves in towards shallower sand flats using contractions of the entire colony. These organisms love to anchor down in sand flats and are often found living completely buried in the sand.