The Crown Urchin, also known as the Tuxedo Urchin, seems less spiny than other urchins at first glance. They are peaceful herbivores whose unique habits can make for interesting aquarium viewing.

Crown Urchins are sensitive to water quality. They will not tolerate copper based medications, high nitrate levels, or fluctuations in alkalinity. Poor water quality can cause an urchin to lose its spines and die. Provided with good water quality, an ailing Crown Urchin may regenerate its spines and recover. Although the spines of Crown Urchins are venomous, they are very short and not particularily sharp. In fact, they alsmost have a fuzzy appearance. They are rather retiring and spend much of their time hiding under rockwork or camouflaging themselves with coral rubble. Plenty of hiding places should be provided. At night, Crown Urchins feed on algae and other plant material that they can find in their habitats. Most will appreciate algae covered grazing areas near hiding places or niches. Although Crown Urchins are found alone in nature, they may be kept in small groups in captivity, although usually an aquarium will not provide a good habitat for more than three of these animals.

The Crown Urchin normally grows to a diameter of 2 to 3 inches (5 to 8 centimeters), excluding the length of its short spines. The Crown Urchin's body is brown in color, and has several dark blue bands radiating from the center, where no spines grow. In some specimens, these areas may be black, olive, or even whitish in color. This pattern of bands and spines resembles a crown and is the origin of the common name. Cilia (fine hairlike structures) protrude from the urchin's body, and are used to grasp materials used to camouflage the urchin. The spines, which are generally dark, reddish or brown in color, may have light bands.

Crown Urchins are found at depths between 3 and 20 feet (1 and 5 meters). They are found in the eastern Indian Ocean and the western Pacific Ocean.

Although bright lighting is acceptable in a tank where Crown Urchins are kept, these creatures prefer the shaded areas of an aquarium. Temperatures from 75 to 78 degrees Fahrenheit (24 to 26 degrees Celsius) are acceptable. Crown Urchins are very sensitive to changes in alkalinity, so the pH of a tank where a Crown Urchin is kept must be held constant. It should remain at 8.3 or 8.4. The specific gravity should be between 1.023 and 1.025. Crown Urchins cannot tolerate high nitrate levels or copper based medications. If this urchin dies, it can release a toxic substance into the aquarium, so it should be removed immediately. The spines are mildly venomous, and you should use care when handling them. Under poor conditions, an unhealthy urchin may lose its spines, though some will recover and regenerate their spines if water quality is restored soon enough. Crown Urchins may be kept in groups or individuals. Plenty of hiding places should be provided. If there is not enough algae present in the tank for the Crown Urchins to graze on, their diets may be supplemented with dried seaweed.

There is currently no special breeding information in our databases for this animal. To submit breeding / propagation information that is specific to this animal please click here.