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:
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Grazes on algae, detritus, and biofilm.
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May nibble on sponges, soft corals, or sessile invertebrates in captivity.
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Supplement diet with nori, spirulina, or algae wafers if natural growth is insufficient.
Tank Mates:
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Generally peaceful, but can be at risk from predators like triggerfish, puffers, or large Wrasses.
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Best kept with reef-safe fish.
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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:
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Temperature: 72–78°F (22–26°C)
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pH: 8.1–8.4
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Salinity: 1.023–1.025
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Tank Size: 75+ gallons
Unique Features:
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Nicknamed “Mine Urchin†due to its resemblance to old naval mines.
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Strong, blunt pencil-like spines instead of sharp ones.
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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?