FaunaHub

Sea Fan (gorgonians, e.g. Gorgonia ventalina)

Marine invertebrateCnidarianSoft coral

Purple sea fan (Gorgonia ventalina), a flat, net-like soft coral.

Common sea fan (Gorgonia ventalina), Cuba.

Image: Tisquesusa, CC BY 4.0, via Wikimedia Commons.

Overview

Sea fans are soft corals — specifically gorgonians — that grow as flat, flexible, net-like fans, often in striking purples, reds, or yellows. The common sea fan (Gorgonia ventalina) of the Caribbean is a familiar example. Unlike the stony reef-builders, gorgonians have a flexible internal skeleton, so they bend and sway with the water rather than forming rigid rock.

A sea fan is a colony of many tiny polyps, and gorgonians belong to the octocorals — soft corals whose polyps each bear eight feathery tentacles.

Note: sea fans are part of reef communities and share many of the pressures facing reefs, including warming, disease, and damage from contact. Treat details as general and verify against authoritative sources.

Habitat & Range

Sea fans grow on tropical and subtropical reefs, typically attached to hard surfaces where currents are reliable. They orient their broad face across the prevailing current — a position that maximises their ability to filter food from passing water.

Diet

Sea fans are filter feeders. The polyps along their branches extend tiny tentacles to capture plankton and suspended particles carried by the current. Many gorgonians also host symbiotic algae that contribute energy through photosynthesis, though the balance varies between species.

Behavior

Because the colony stands across the current to feed, sea fans often grow in a single plane aligned with water flow. Their flexible skeleton lets them flex in surge and waves instead of snapping. Like other corals, they grow slowly, and the polyps can withdraw for protection.

Human Interaction & Conservation

Sea fans add structure, colour, and feeding habitat to reefs and shelter many small animals. They are sensitive to being touched or broken by divers and anchors, and to reef-wide stressors such as warming water and disease. As with all reef life, careful interaction and reef conservation matter. Consult authoritative sources for current status.

More photos of the sea fan

A sea fan spread across the current to filter-feed.

Common sea fan (Gorgonia ventalina).

Image: Paul Asman and Jill Lenoble, CC BY 2.0, via Wikimedia Commons.

Frequently Asked Questions — Sea Fan

Is a sea fan a coral or a plant?
A sea fan is an animal — a soft coral (gorgonian), and a colony of many tiny polyps. Its branching, plant-like shape and sometimes algae-assisted nutrition can make it look plant-like, but it belongs to the same broad group as other corals and sea anemones.
Why do sea fans grow flat, facing the current?
Sea fans are filter feeders, so growing as a flat fan oriented across the prevailing current maximises the water — and the plankton it carries — that passes through the colony. This positioning makes feeding far more efficient.
How is a sea fan different from a stony coral?
Stony (hard) corals build a rigid calcium-carbonate skeleton that forms reef rock, while sea fans are soft corals with a flexible internal skeleton that bends with the water. Sea fans are octocorals, with polyps that each have eight tentacles.
What do sea fans eat?
They filter plankton and fine particles from the water using their polyps' tentacles. Many also gain some energy from symbiotic algae living in their tissues, depending on the species.

Sources and further reading

Authoritative wildlife references used for general educational context. Conservation status should always be verified against current IUCN Red List data. External links open in a new tab.