About Collector Urchin
Collector urchin — covers itself in shells, rubble, and frags it picks up off the substrate (yes, including the ones you just glued down). Excellent algae grazer for larger reefs where its decorating habit is charming, not infuriating.
Tripneustes gratilla, the collector urchin or halloween urchin, is a species of sea urchin. Collector urchins are found at depths of 2 to 30 metres in the waters of the Indo-Pacific, Hawaii, the Red Sea, and The Bahamas. They can reach 10 to 15 centimetres in size.
Notes from the editors
What it looks like. Medium-sized urchin (3–6 inches) that covers itself with shells, rubble, and small frags it picks up off the substrate. Often called the "collector urchin" or "tuxedo urchin" depending on color.
In your tank. Excellent algae grazer. The decorating habit is endearing in larger reefs and infuriating in smaller ones (will collect frags you just glued down).
Care notes. Reef-safe with caution. Won't tip over rockwork like some larger urchins, but will move whatever isn't secured.
Sourcing and feeding. Wild-collected from Indo-Pacific reefs; mid-priced ($20–50). Herbivore — algae, nori sheets.
Care info is a starting point, not a guarantee. Individual specimens, water chemistry, and tankmate dynamics vary. Verify against multiple sources and adjust to what you observe. See our terms & disclaimers.
Related invertebrates
Sources & attribution
- Taxonomy and accepted name from the World Register of Marine Species (WoRMS AphiaID 212453).
- Description content adapted from Wikipedia, available under CC BY-SA 4.0.
- Photo: (c) Jacek Pietruszewski, some rights reserved (CC BY) · CC-BY (via iNaturalist or Wikimedia Commons).