‘The Squat Urchin Shrimp’
Gnathophylloides mineri on Tripneustes ventricosus
Music, Video, and Aquarium
2010 Coral Morphologic

The Squat Urchin Shrimp (Gnathophylloides mineri) is an amazingly successful creature that can be found living amongst the spines of sea urchins throughout most of the world’s shallow tropical waters. In the Caribbean they hitchhike exclusively upon the black and white West Indian Sea Egg (Tripneustes ventricosus), traveling along where ever its host may go. The squat urchin shrimp is very small, reaching no more than 6mm in length, and orients itself parallel with the spines making it all but invisible and protected from a would-be-predator. Often colonies of up to half a dozen squat urchin shrimp of varying sizes will all share the same urchin. Beyond its circumtropical distribution and perfect camouflage, the squat urchin shrimp further demonstrates its successfulness by feeding upon the epidermal tissue of the very spines that grant it protection. This is a relatively benign form of parasitism that doesn’t seem to bother the urchin. These shrimp will also feed opportunistically upon detritus that the urchin picks up as it moves along the sea floor. The squat urchin shrimp is a creature that has found a near perfect niche in a truly self-sustaining, self-contained world of spines.