Animals with a ring of feathery tentacles or arms
How to tell them apart?
updated Apr 2020

Several animals with a ring of feathery tentacles are sometimes confused for one another.
Here's how to tell them apart.

Fanworms have a fan of feathery tentacles that sticks out of the tube while the segmented body remains hidden. Feather stars have 10 or more feathery arms arranged around a small central disk. Sea cucumbers have many feathery tentacles surrounding their mouth. Often, only the tentacles stick out while the body of the sea cucumber is buried or hidden in a crevice.
Fanworms build tubes to hide in and usually do not move once they settle down. Feather stars can move about, some can even swim. Sea cucumbers can move but most usually stay put once they find a safe hiding place from which they can feed.
Fanworms can retract their tentacles leaving only their soft limp tubes visible. Feather stars may curl up their arms, but they don't build tubes to hide in. Sea cucumbers can tuck their tentacles into their bodies.
Fanworms may be found on coral rubble and even among living hard corals. They are quite common on our undisturbed shores. Feather stars are only commonly seen on remote and undisturbed shores. Sea cucumbers are common on all our shores in a wide range of habitats.
Fanworms belong to Phylum Annelida, Class Polychaeta and most of those we see on the shores belong to Family Sabellidae. Feather stars belong to the Phylum Echinodermata, Order Crinodea. Sea cucumbers belong to the Phylum Echinodermata, Order Holothuroidea.

More comparisons

brittle stars have bristley arms
but only five arms.

Feeding tentacles of a buried sea cucumber

Feathery soft coral: a colony of
polyps with feathery tentacles.

Frilly sea anemone with
feathery tentacles expanded.

Fire anemone with
feathery tentacles expanded.
Has central mouth with white radiating lines.

Asparagus flowery soft coral.
NO central mouth, NO radiating lines.

Hydroids have feathery forms.

Cerianthid phoronid worms are not fan worms.

Keelworms also have a fan.

Fanworms have a segmented body and the fan
may appear petal-like when stuck
together at low tide.

how to tell apart bristley animals
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