Common name: pencil urchin

General information

The Slate Pencil Urchin, scientifically known as Phyllacanthus imperialis, is a striking marine invertebrate known for its thick, cylindrical spines that resemble chalk sticks or pencils. These spines are often reddish-brown to purple in color and can be quite long, providing the urchin with an effective defense mechanism against predators. The Slate Pencil Urchin is a member of the family Echinometridae and is found in various parts of the Indo-Pacific region.

Care

In the aquarium, Slate Pencil Urchins require a stable environment with plenty of live rock for grazing and hiding. They are generally hardy and can adapt to a range of water conditions, but they do best in well-established tanks with consistent water quality. It's important to provide them with ample space to move around, as their spines can inadvertently damage corals and other invertebrates if the tank is too crowded.

Reproduction

Slate Pencil Urchins reproduce by releasing gametes into the water column, a process known as broadcast spawning. In the home aquarium, breeding is rare, but with optimal conditions, it is possible to observe spawning behavior. The larvae that result from fertilization are planktonic and go through several developmental stages before settling to the bottom and metamorphosing into juvenile urchins.

Symbiosis

While not known for specific symbiotic relationships like those seen in clownfish and anemones, Slate Pencil Urchins do play a role in the reef ecosystem by controlling algae growth. Their grazing helps prevent algae overgrowth, which can be beneficial to corals and other reef inhabitants.

Habitat

The natural habitat of the Slate Pencil Urchin includes reef slopes and lagoons, where they can be found at various depths. They are often seen nestled in crevices during the day and become more active at night. In the aquarium, providing a similar environment with plenty of crevices and live rock will help mimic their natural habitat and promote natural behavior.