Brock's Urchin Shrimp

Allopontonia brockii

Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Family: Palaemonidae
Genus: Allopontonia
Species: Allopontonia brockii

Brock's urchin shrimp (Allopontonia brockii) is a small, striped shrimp that lives among the spines of fire urchins and other sea urchins. Its body is marked with lines and bands that match the colours of its host.

It grows to about 1-2 cm and clings to the urchin's skin between the spines, where few predators dare to follow. It feeds on particles and tissue from its host, and is often found alongside other urchin commensals such as Coleman shrimp and zebra crabs.

Fire urchins on sandy slopes in the Philippines are a good place to look for this shrimp. Always keep a safe distance, as the spines of fire urchins are venomous.

Photo: Pierre Pericard, CC BY 4.0, via iNaturalist