What Divers Should Know About Gorgonian

Gorgonians, familiar to many divers as sea fans and sea whips, are captivating colonial organisms within the Octocorallia, a diverse group often informally referred to as "soft corals." These marine animals are distinguished by their polyps, which invariably display eight-fold symmetry. Unlike the stony corals, the many thousands of species of Octocorallia lack a rigid, stony skeleton, with their polyps typically embedded within a softer, flexible matrix that forms the colony's visible structure.

Upon closer inspection, each polyp features eight distinctive, feather-like tentacles, adorned with numerous tiny side branches called pinnules. These individual polyps are sessile, meaning stationary, with only their uppermost parts, including the tentacles and mouth, extending from the colony's surface. While the colonies are generally soft to the touch, their internal structure is often reinforced by either calcareous or horny material, secreted by the polyps' mesoglea.

These ancient organisms have a lineage extending back at least to the Ordovician period. Among their fascinating characteristics, bioluminescence has evolved in 32 genera, a trait estimated to have appeared over 500 million years ago, representing the earliest known emergence of bioluminescence in marine environments.