Echinothrix calamaris

(Pallas, 1774)

Double-spined Urchin, Banded Sea Urchin, Hat Pin Urchin

Range: Indo-West Pacific Ocean: Red Sea to Hawaii.

Size: 6 inches (15 cm)

Natural Environment: Inhabits shallow reef areas and lagoons and found on rock and rubble areas covered in algae.

General Husbandry: Occasionally 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 algae as a juvenile, yet tends to be more carnivorous as it grows into adulthood and includes sponges, corals, bivalves, gastropods, bryozoans, along with detritus in its diet.

Can maintained in a reef aquarium, yet not without careful observation as to its targeted food preferences. Probably better suited for fish-only aquariums.

Should, when seen moving, be fed small pieces of fish or mussel flesh daily.

Not safe small clams, tubeworms, snails and other small invertebrates.

Taxonomy:

Kingdom: Animalia

Phylum: Echinodermata

Class: Echinoides

Order: Diadematoida

Family: Diadematidae

Genus: Echinothrix

FYI: Vulnerable to sudden salinity/specific gravity changes.

Triggerfish and large wrasses will eat these urchins.

Experience Level: Intermediate

Diet: Omnivore

Aquarium Environment: Reef or fish-only aquarium

Coral Safe: With caution

Fish Safe: Yes

Invertebrate Safe: With caution

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: 150 gallons

Specific Gravity: 1.023 - 1.025

pH: 8.0 - 8.4