TankBud

Shingle urchin

Colobocentrotus atratus

Also known as Helmet urchin, Shield urchin, Plate urchin

SaltwaterInvertebrate

Care at a glance

Temperature
73–82°F
23–28°C
pH
8.1–8.4
Adult size
3.9 in
10 cm
Minimum tank
53 gal
200 L
Temperament
Peaceful
Social behavior
Solitary
Tankmates
With caution
Swim level
Bottom
Diet
Herbivore
Difficulty
Difficult
Breeding
No record
Rarity
Very rare
Reef safe
Reef safe with caution
Family
Echinometridae
Origin
Wave-swept Indo-West Pacific rocky shores, especially Hawaii

Overview

The shingle urchin is a peaceful, limpet-shaped urchin for a saltwater tank with very strong flow. It is for experienced keepers.

Did you know

The shingle urchin stayed put in a lab flume at 17.5 m per second, and some held at 27.5 m per second. Water that fast would strip most animals off the rock, and even the lower speed is roughly three times what a rock-boring urchin survives. The trick is not the helmet shape but the sheer number of tube feet glued to the rock.

Caring for the shingle urchin

Give the shingle urchin a tank of at least 53 gal (200 L) and bare rock thick with coralline algae. The flow must be very strong, surging and well oxygenated, though no home tank reproduces the surf it is built for. Most shingle urchins fade over months in still, warm water. A few keepers report years with one on the glass under very high flow.

Keep the water at 73 to 82°F (23 to 28°C) with a pH of 8.1 to 8.4, and hold nitrate low. Drip acclimate it, and never use copper. It has no venom and can be handled. Its grip is so strong, though, that pulling it off the glass tears its tube feet.

The shingle urchin scrapes coralline algae and algal film from the rock with its lantern. Once the coralline is gone, feed dried seaweed pressed onto the rock.

It is peaceful, harmless to fish and does not eat coral tissue. It is still a reef caution, because it strips coralline algae bare.

Good to know

Colobocentrotus atratus is a regular urchin in the family Echinometridae, the same family as the rock-boring urchin. Its upper spines are flattened and fused into a smooth mosaic of dark maroon plates, like roof shingles. A skirt of paddle-shaped spines rings the rim, giving the dome-shaped test a limpet shape that sheds waves. In Hawaii, where it is most abundant, it is gathered as food, and almost none reach the aquarium trade.

In the wild

The shingle urchin lives on the most wave-beaten intertidal rock in the Indo-West Pacific. Its range runs from Sri Lanka and the Bay of Bengal through Indonesia to Hawaii. In Hawaii it is known as ha'uke'uke and is common on black lava shores pounded by surf. It sits in the open in clusters at and just below the tide line, in the top 5 m.

Common questions

What size tank does a shingle urchin need?

A shingle urchin needs at least 53 gal (200 L). It spends most of its time in the bottom.

What temperature and pH does a shingle urchin need?

A shingle urchin is comfortable at 73–82°F (23–28°C) with a pH of 8.1–8.4.

What does a shingle urchin eat?

A shingle urchin scrapes coralline algae and algal film off the rock. Once the coralline runs out, feed it dried seaweed pressed onto the rock.

How big does a shingle urchin get?

An adult shingle urchin reaches about 3.9 in (10 cm).

Related species