Common name: variable fire urchin

General information

The Fire Urchin, scientifically known as Asthenosoma varium, is a striking and colorful echinoderm that is often sought after by advanced aquarists for its unique appearance. This species is known for its vibrant red, orange, and purple hues, along with its thick, venomous spines that can inflict painful stings. Despite its beauty, it is essential to handle this urchin with care due to its venomous nature.

Care

Fire Urchins require a specialized environment to thrive in captivity. They need a spacious tank with plenty of live rock and a stable, mature marine ecosystem. The substrate should be fine to prevent injury to the urchin's delicate tube feet. It is crucial to maintain excellent water quality with stable parameters, as Fire Urchins are sensitive to fluctuations in water chemistry.

Reproduction

In the wild, Asthenosoma varium reproduces by releasing eggs and sperm into the water column, where fertilization occurs externally. In the aquarium, breeding Fire Urchins is quite challenging and rarely observed. Hobbyists should focus on providing optimal care rather than attempting to breed this species.

Symbiosis

Fire Urchins have a fascinating symbiotic relationship with certain species of small commensal shrimps and crabs, which live among the urchin's spines for protection. These creatures help keep the urchin clean by feeding on detritus and parasites.

Habitat

Native to the Indo-Pacific region, Fire Urchins are typically found in coral reef environments and rocky areas where they graze on algae and detritus. They are nocturnal and often hide during the day, emerging at night to feed.