How big is an arrow crab?

The body is tiny; the leg span is five to ten centimetres.

When do you see them?

Mostly at night, though they can be found in crevices during the day.

A long striped rostrum, spindly legs and violet claw tips.

In crevices and around sponge bases across the Cozumel reefs.

Yellowline Arrow Crab (*Stenorhynchus seticornis*) in Cozumel: how to identify it, where it hides, and when it is visible.

A tiny triangular body on absurdly long thin legs, with a long spiked rostrum striped in gold and brown, and violet claw tips.

Scientific name	Stenorhynchus seticornis
Group	Crustaceans — Lobster, Shrimp & Crabs
Typical size	5–10 cm leg span
Depth range	3–30 m
When to see it	Year-round
Active	Mostly night
Conservation status	Least Concern
Notes	Best seen on night dives

Crevices and sponge bases at Palancar, Yucab and Santa Rosa, most visible on night dives.

Scavenges small invertebrates and detritus. Often shares a crevice with an anemone or a cleaner shrimp.

Channel clinging crab — Far larger and heavy-bodied with thick legs.
Other spider crabs — The gold-and-brown striped rostrum and violet claw tips are diagnostic.

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