Long Spine Urchin

The Long Spine Urchin (Diadema setosum) is a striking and highly effective algae-eating invertebrate, instantly recognizable by its dramatically long, needle-like spines that can extend several inches from its body.

Care Level & Requirements

• Care Level: Moderate
• Temperament: Peaceful
• Minimum Tank Size: 50+ gallons
• Diet: Herbivore - algae grazer
• Reef Safe: Yes

What to Expect

The Long Spine Urchin is one of nature's most efficient algae control specialists, constantly grazing on hair algae, film algae, and other nuisance algae throughout your aquarium. Its impressive spines serve as protection from predators and give it a dramatic, architectural appearance as it moves across rockwork and glass.

Behavior & Compatibility

This peaceful herbivore is completely reef-safe and will not harm corals or other invertebrates. Long Spine Urchins are primarily nocturnal but will often graze during the day as well. They have a unique behavior of decorating themselves with shells, rocks, and algae fragments, which they hold with their tube feet for camouflage.

Important Handling Notes

Caution: The spines are extremely sharp and can cause painful puncture wounds. Always use caution when working in the aquarium and never handle directly. The spines are brittle and can break off if the urchin is disturbed or handled roughly.

Tank Considerations

Provide stable rockwork, as Long Spine Urchins can accidentally knock over loose coral frags or decorations while moving. Ensure adequate algae growth or supplement with dried seaweed (nori) if natural algae is limited. They require stable water parameters and are sensitive to copper-based medications.

Acclimation

Use a slow drip acclimation method over 45-60 minutes. Urchins are sensitive to changes in salinity, pH, and specific gravity. Never expose to air during acclimation or transfer, as air bubbles can become trapped and cause harm.

Our Live Arrival Guarantee

Every Long Spine Urchin ships with our live arrival guarantee, carefully packed to ensure it arrives healthy and ready to control algae in your reef system.