Colobocentrotus altratus

(Linnaeus, 1758)

Shield Urchin, Helmet Urchin

Range: Indo-West Pacific Ocean: Eastern Africa to Hawaii.

Size: 3 inches (7 cm)

Natural Environment: Inhabits intertidal zones.

General Husbandry: Rarely seen in the home aquarium trade.

Basically stays still, usually under ledges during daylight hours and when evening arrives, begins its search for food, usually coralline algae.

Can be maintained in a reef or fish-only aquariums having a wide covering of coralline algae, as this is the species main food.

Has a desire for calcium carbonate, which is a mainly coralline alga. Therefore can be given pieces of cuttlebone or algae blocks to prevent it from consuming coralline algae, which most aquarists cherish. Place in aquarium in early evening hours.

In aquariums somewhat devoid of algae, small plaster-of-Paris feeding stones that contain seaweed and algae can also sometimes help lengthen lifespans of these urchins in aquariums.

Sheets of Nori weighted down with small rocks may also help keep this species well fed.

Taxonomy:

Kingdom: Animalia

Phylum: Echinodermata

Class: Echinoides

Order: Echinoida

Family: Echinometridae

Genus: Colobocentrotus

FYI: Vulnerable to sudden salinity/specific gravity changes.

Triggerfish and large wrasses will eat these urchins.

Experience Level: Intermediate

Diet: Herbivore

Aquarium Environment: Reef or fish-only aquarium

Coral Safe: Yes

Fish Safe: Yes

Invertebrate Safe: Yes

Acclimation Time: Sensitive to specific gravity/salinity changes, therefore be sure to adjust the bag's water to that of the aquarium in which it will be placed by slowly adding small amounts of aquarium water to the bag every few minutes. In most cases, this process should take at least 15 minutes.

Aquarium Hardiness: Moderately hardy

Temperature Range: 72 - 83°F (22 - 28°C)

Minimum Tank Size: 60 gallons

Specific Gravity: 1.023 - 1.025

pH: 8.0 - 8.4