Rock Boring Urchin Care Guide
Echinometra mathaei is a small Indo-Pacific urchin that bores into rock and coral. It grazes algae but its burrowing causes reef bioerosion.
Compiled by Aquairi from published sources · Published · Updated
Overview
Echinometra mathaei, the rock-boring urchin, is a small echinoid of the family Echinometridae from the Indo-Pacific. It is generally dark with short, stout spines that may be green and purple-tipped, and shows a characteristic pale ring at the base of each spine. It uses its spines and teeth to excavate hollows in rock, sheltering by day and grazing algae at night.
Taxonomy
- Class: Echinoidea
- Order: Camarodonta
- Family: Echinometridae
- Genus: Echinometra
- Scientific name: Echinometra mathaei (Blainville, 1825)
Habitat
The species occurs throughout the Indo-Pacific from Madagascar and the Red Sea to Hawaii, on tropical reefs at depths down to about 139 m. It digs into basaltic and calcareous rock, living in the hollows it creates.
Tank requirements
- Minimum tank volume: 80 L
- Temperature: 24–26 °C (75–79 °F)
- pH: 8.1–8.4
- Carbonate hardness (dKH): 8–11
- Specific gravity: 1.024–1.026
- Adult test diameter: about 5 cm
- Lifespan: roughly 3–5 years
Provide solid live rock with crevices and stable parameters; be aware the urchin may enlarge holes in softer rock over time.
Diet
Echinometra mathaei is herbivorous, emerging from its hollow at night to graze algae on the surrounding rock.
Compatibility
It is largely reef compatible as an algae grazer, but its boring behaviour can damage soft live rock and undermine rockwork, so it is best treated as reef-cautious. Avoid urchin predators such as triggerfish and pufferfish.
Ecological role
Through burrowing the species contributes significantly to bioerosion of coral reefs; where predators such as finfish and gastropods are reduced by fishing, urchin numbers and reef damage can increase.
Echinometra mathaei Breeding Guide
Overview
Echinometra mathaei is a small urchin of tropical Indo-Pacific reefs, ranging from Madagascar, the East African coast and the Red Sea to Hawaii. It uses its spines and the teeth of its Aristotle's lantern to bore into basaltic and calcareous rock, emerging from these hollows at night to graze on algae. Its test reaches about 5 centimetres in diameter.
Reproductive Mode
As with other sea urchins, breeding involves releasing gametes into the water column, so the species is a broadcast spawner with separate sexes and external fertilisation. In the Gulf of Suez it spawns in summer and autumn, but in warmer waters breeding can take place at any time of year.
Sexual Reproduction
Fertilisation in open water gives rise to echinopluteus larvae that are planktonic. When these settle on the seabed they undergo metamorphosis into juvenile sea urchins. The long planktonic phase ties recruitment to open-ocean conditions rather than to the parent's immediate habitat.
Common Challenges
The planktonic larval stage demands months of suspended culture on microalgae, which cannot be reproduced in a display reef tank. Spawning events may occur in captivity, but the larvae are not raised and no juveniles are recovered.