Jewel Urchin

Lytechinus williamsi

Also known as Williams' Variable Sea Urchin

SaltwaterInvertebrate

Jewel Urchin (Lytechinus williamsi) — (c) Robin White, some rights reserved (CC BY) · CC BY

Care at a glance

Temperature: 72–81°F (22–27°C)
pH: 8.1–8.4
Adult size: 2 in (5 cm)
Minimum tank: 11 gal (40 L)
Temperament: Peaceful
Social behavior: Solitary
Swim level: Bottom
Difficulty: Easy
Breeding: Hard
Rarity: Rare
Reef safe: Reef safe with caution
Origin: Caribbean, from the Florida Keys to Panama
Family: Toxopneustidae

Overview

A peaceful, compact grazer that patrols rock and glass for film algae and tougher growth, quiet cleanup crew work in a small package. Like other urchins it picks up small rocks, shells, and loose frags as it moves, so glue frags down. Offer nori once the natural algae runs low.

In the wild

Lives on shallow Caribbean reefs off Panama, Belize, Jamaica, and the Florida Keys, often tucked in among coral heads and rubble. In the aquarium it wants plenty of rockwork carrying a natural algae film to graze.

Good to know

Lytechinus williamsi is a small regular urchin in the family Toxopneustidae, described in 1968, with deep green or white spines up to about 3 cm long over a test of 3 to 5 cm. Between the spines sit large purple tweezer-shaped structures called pedicellariae, which make the species easy to recognize.

Did you know

The purple pedicellariae scattered between its green spines are tiny gripping organs, hundreds of miniature tweezers the urchin uses to keep its surface clean, and they are what give it the jeweled look behind the common name.