Description

Mine Sea Urchin – Eucidaris tribuloides

(Also known as: Pencil Urchin, Caribbean Mine Urchin)

Overview:
The Mine Sea Urchin is a stout-bodied urchin with thick, blunt, cylindrical spines that resemble the spikes of an underwater mine – hence its common name. Unlike long-spined urchins, its spines are short, strong, and less sharp, making it less dangerous to handle (though still prickly). It’s a slow-moving grazer that contributes to reef cleanup but may sometimes feed on soft corals and sponges.

Origin:
Native to the Caribbean Sea, Gulf of Mexico, and Western Atlantic Ocean, usually found on reefs, rocky substrates, and seagrass beds.

Feeding:

Grazes on algae, detritus, and biofilm.
May nibble on sponges, soft corals, or sessile invertebrates in captivity.
Supplement diet with nori, spirulina, or algae wafers if natural growth is insufficient.

Tank Mates:

Generally peaceful, but can be at risk from predators like triggerfish, puffers, or large wrasses.
Best kept with reef-safe fish.
May not be completely reef safe, as it can eat coralline algae and soft corals if underfed.

Aggression Level:
Non-aggressive, but its spines can cause discomfort if touched.

Experience Level:
Intermediate – requires a mature tank with consistent algae growth and careful placement to prevent toppling corals.

Water Parameters:

Temperature: 72–78°F (22–26°C)
pH: 8.1–8.4
Salinity: 1.023–1.025
Tank Size: 75+ gallons

Unique Features:

Nicknamed “Mine Urchin” due to its resemblance to old naval mines.
Strong, blunt pencil-like spines instead of sharp ones.
Often used in aquariums for algae control, though with caution.

✨ The Mine Sea Urchin is a hardy and fascinating addition to a marine system, offering both utility as an algae grazer and a unique appearance, though it requires careful reef placement due to its diet.

Would you like me to also prepare a side-by-side comparison of the Mine Urchin vs. the more commonly sold Pencil Urchin (Eucidaris sp.) for your store listings?