TankBud

Sputnik urchin

Phyllacanthus imperialis

Also known as Imperial urchin, Imperial sea urchin, Imperial lance urchin, Knobby sputnik urchin

SaltwaterInvertebrate

Care at a glance

Temperature
72–81°F
22–27°C
pH
8.1–8.4
Adult size
3.9 in
10 cm
Minimum tank
79 gal
300 L
Temperament
Peaceful
Social behavior
Solitary
Tankmates
With caution
Swim level
Bottom
Diet
Omnivore
Difficulty
Medium
Breeding
No record
Rarity
Very rare
Reef safe
Reef safe with caution
Family
Cidaridae
Origin
Indo-West Pacific reefs, Red Sea and East Africa to the western Pacific

Overview

The Sputnik urchin is a slow, peaceful cidaroid urchin for a large fish-only or rubble tank. It is best with a little experience.

Did you know

The Sputnik urchin's name comes from the first satellite. With its round body and thick spines sticking out at all angles, a bare test looks like the 1957 Sputnik. Dried ones are sold by the thousand as shell shop decorations under that name.

Caring for the Sputnik urchin

Keep the Sputnik urchin in a large, mature fish-only or rubble tank of at least 79 gal (300 L). Lock heavy rock in place, and leave caves wide enough for a 30 cm spine span. Keep the light dim, because it stays hidden under bright lamps.

Hold the water at 72 to 81°F (22 to 27°C) and a pH of 8.1 to 8.4, and keep nitrate low. Never use copper. Drip acclimate it slowly.

It eats algae, sponges and small encrusting invertebrates at night. Algae alone may not carry it, so offer dried seaweed, sinking pellets and bits of shellfish after dark. Expect to see it mostly after lights out.

The Sputnik urchin is slow moving and peaceful toward fish, but its appetite for sponges and encrusting animals makes it a reef caution. Its weight and stiff spines also knock frags off the rock. Triggers, puffers and large wrasses will chew on it.

Good to know

Phyllacanthus imperialis is a cidaroid, from the ancient lineage of pencil urchins in the family Cidaridae. Its test carries a few very thick, blunt, club-shaped primary spines, roughly as long as the test is wide. They are ringed by short, flattened secondary spines. Cidaroid spines have no living skin over them, so algae, sponges and bryozoans colonize them. A live animal ends up looking like a mossy satellite. Live ones are seldom offered, and almost nothing is published on keeping them.

In the wild

The Sputnik urchin lives on sheltered reef slopes and lagoon rock across the Indo-West Pacific. It ranges from the Red Sea and East Africa to the Philippines and northern Australia. By day it sits jammed in a hole in the reef, and at night it comes out to feed.

Common questions

What size tank does a Sputnik urchin need?

A Sputnik urchin needs at least 79 gal (300 L). It spends most of its time in the bottom.

What temperature and pH does a Sputnik urchin need?

A Sputnik urchin is comfortable at 72–81°F (22–27°C) with a pH of 8.1–8.4.

What does a Sputnik urchin eat?

A Sputnik urchin eats algae, sponges and small encrusting invertebrates at night. Algae alone may not carry it, so offer dried seaweed, sinking pellets and bits of shellfish.

How big does a Sputnik urchin get?

An adult Sputnik urchin reaches about 3.9 in (10 cm).

Related species