Longspine heart urchin

Care at a glance

Overview

The longspine heart urchin is a peaceful urchin that burrows through the sand of a large, mature tank. It is hard to keep and suits experienced keepers.

Caring for the longspine heart urchin

Keep the longspine heart urchin only in a large, old, lightly cleaned tank. Plan on at least 53 gal (200 L), so the sand bed is big enough to hold food. Lay a live sand bed at least 10 cm deep, of mature coarse sand or crushed coral over a wide, open footprint. Fine sugar sand or mud can smother it.

Keep the water at 73 to 81°F (23 to 27°C) with a pH of 8.1 to 8.4 and steady salinity. Acclimate it slowly by drip, and never lift it into the air. Keep copper medications out of the tank.

The longspine heart urchin is a deposit feeder and spends most of its time out of sight below the surface. It swallows sand and digests the bacteria, diatoms and detritus in it, feeding around the clock. Most home tanks do not produce enough of that food, so it usually starves, and it gives no warning before it dies.

It is peaceful and completely harmless to corals and fish. Leave out sand-sifting gobies, sea cucumbers and crabs, which compete for the same food. Puffers, triggers and large wrasses would bite it, so keep them out as well.

Good to know

The longspine heart urchin, Maretia planulata, is a heart urchin in the family Maretiidae, order Spatangoida. Its test is oval and covered in short spines. Longer fine spines sweep backward and give it its trade name. It has no Aristotle's lantern, so it cannot scrape algae off rock the way regular urchins do. Other names for it include fine-spined heart urchin and sea mouse urchin.

In the wild

The longspine heart urchin lives buried in sandy intertidal flats and seagrass beds across the Indo-West Pacific, down to about 60 m. It is an irregular urchin that plows through sand rather than grazing rock. Heart urchins turn over huge volumes of sediment and are counted among the important bioturbators of tropical sand flats.

Common questions

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