Slate Pencil Urchin (Eucidaris tribuloides)

Description

One Slate Pencil Urchin, hand-collected and quarantined right here in Key West. Photographed under blue spectrum reef lighting, this specimen shows the classic thick, blunt spines in warm plum and rust tones, ringed with pale banding and dusted with coralline growth — a living piece of Florida Keys reef structure for your display tank.

About the Slate Pencil Urchin (Eucidaris tribuloides)

Also called the rock-boring pencil urchin, this Atlantic and Caribbean species is one of the most recognizable inverts on the Florida Keys reef tract. Unlike long-spined urchins, its heavy cigar-shaped spines are blunt and harmless to handle, and they often accumulate coralline algae and encrusting life that make each animal look different. It is a patient nocturnal grazer that spends the day tucked into rockwork and comes out after lights-out to work over algae film and detritus. Locally collected stock adapts quickly to captive systems and arrives already acclimated to our water.

Care Guide

An easy, hardy invert that rewards a mature tank with steady algae control and a lot of character.

• Lighting: Not light-dependent; any standard reef lighting is fine. Provide shaded caves for daytime hiding.
• Flow: Low to moderate — needs open rock surfaces it can grip and graze.
• Placement: Rockwork and sandbed; it will relocate itself nightly.
• Feeding/Nutrients: Grazes film algae, coralline, and detritus; supplement with dried seaweed or sinking pellets in clean, low-algae systems.
• Aggression/Reef Safe: Reef safe with caution — peaceful toward fish and corals, but a large urchin can bulldoze unglued frags and will scrape coralline. Secure loose frag plugs.
• Water Parameters: Stable reef parameters required — Temp 76-78°F, pH 8.1-8.4, Salinity 1.024-1.026. Sensitive to rapid parameter swings and copper-based medications. Acclimate slowly by drip.

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