Prionocidaris baculosa

(Lamarck, 1816)

Crown-spined Pencil Urchin

Range: Indo-West Pacific Ocean

Size: 7 inches (17 cm)

Natural Environment: Inhabits protected reef areas and hides during daytime and feeds on sponges, invertebrates, detritus, and dead animals at night.

General Husbandry: Occasionally seen in the home aquarium trade.

Basically stays still, usually under ledges during daylight hours and when evening arrives, begins its search for food, which can include sponges, corals, bivalves, gastropods, bryozoans, along with detritus and some algae.

Can be maintained in a reef aquarium, yet not without careful observation as to its targeted food preferences. Probably better suited for fish-only aquariums.

Should, when seen moving, be fed small pieces of fish or mussel flesh daily.

Not 100% safe small clams, tubeworms, snails and other small invertebrates.

Can be a real bulldozer!

Try feeding algae blocks during evening hours to prevent it from consuming your coralline!

Have a desire for calcium carbonate, which is mainly coralline algae. Therefore can be given pieces of cuttlebone or algae blocks during evening hours to prevent it from consuming your coralline!

In aquariums somewhat devoid of algae, small plaster-of-Paris feeding stones that contain seaweed and algae can also sometimes help lengthen lifespans of these urchins in aquariums.

Taxonomy:

Kingdom: Animalia

Phylum: Echinodermata

Class: Echinoides

Order: Cidaroida

Family: Cidaridae

Genus: Prionocidaris

FYI: Vulnerable to sudden salinity/specific gravity changes.

Spines can be regenerated if broken or lost.

Triggerfish and large wrasses will eat these urchins.

Experience Level: Intermediate

Diet: Omnivore

Aquarium Environment: Fish-only aquarium

Coral Safe: With caution

Fish Safe: Yes

Invertebrate Safe: With caution

Acclimation Time: Sensitive to specific gravity/salinity changes, therefore be sure to adjust the bag's water to that of the aquarium in which it will be placed by slowly adding small amounts of aquarium water to the bag every few minutes. In most cases, this process should take at least 15 minutes.

Aquarium Hardiness: Moderately hardy

Temperature Range: 72 - 83°F (22 - 28°C)

Minimum Tank Size: 100 gallons

Specific Gravity: 1.023 - 1.025

pH: 8.0 - 8.4