# Shingle Urchin (*colobocentrotus atratus*) The Shingle Urchin, also known as the helmet urchin, is a marvel of evolutionary engineering. Clinging to wave-swept basaltic rocks in the Indo-Pacific, this unique marine invertebrate has traded the long, sharp, menacing spines of typical sea urchins for a smooth, interlocking armor of flattened, shingle-like plates. This aerodynamic dome allows it to withstand the crushing force of crashing waves that would easily sweep other creatures away. Beyond its physical resilience, the Shingle Urchin plays a vital role in its intertidal ecosystem by grazing on tough, encrusting algae, maintaining a healthy balance on rocky shores. - **Category:** [Animal](https://www.snappit.app/explore/categories/animal) - **Rarity:** Common - **Danger:** 1/5 · Very low - **Snaps:** 4 - **Habitat:** Found on wave-beaten rocky intertidal shores, particularly on basaltic lava rocks exposed to heavy surf. ![Shingle Urchin](https://inaturalist-open-data.s3.amazonaws.com/photos/27754014/medium.jpg) Photo: John G. Phillips, CC BY 4.0 · [iNaturalist](https://www.inaturalist.org/photos/27754014) ## Appearance This urchin is easily recognized by its distinctive dome-shaped, helmet-like profile, which typically reaches 5 to 8 centimeters in diameter. Its upper surface is covered in dark purple to almost black, flattened, hexagonal plates that fit together like a mosaic, minimizing water resistance. Around the perimeter, a fringe of spatula-like, paddle-shaped spines flares outward, sealing the gap between the shell and the rock. The underside is flat, densely packed with strong tube feet used for gripping. ## Taxonomy - **Kingdom:** Animalia - **Phylum:** Echinodermata - **Class:** Echinoidea - **Order:** Camarodonta - **Family:** Echinometridae - **Genus:** Colobocentrotus ## Interesting facts - In Hawaii, they are known as 'haukeuke' and were historically used by Native Hawaiians as a traditional food source and for making purple dye. - Their flattened spines are so tightly packed that they act like a coat of chainmail, defending them against both predators and crashing waves. - Unlike most sea urchins that cause painful punctures, the Shingle Urchin can be safely touched as its spines are entirely flat and blunt. ## Special abilities - **Hydrodynamic Shielding:** Its flattened, dome-like shape and tightly interlocking shingle-like spines allow turbulent waves to glide harmlessly over its body, minimizing drag. - **Suction Grip:** Utilizes hundreds of specialized tube feet on its flat underside to generate powerful suction, anchoring itself firmly against crushing waves. - **Desiccation Defense:** The tight perimeter of paddle-like marginal spines seals moisture underneath its body, protecting it from drying out during low tide exposures. ## Measurements & details - **Length:** 5-8 cm - **Weight:** 0.05-0.15 kg - **Lifespan:** 5-10 years - **Clutch Size:** 10000-50000 - **Incubation:** 20-30 days ## Diet & Feeding Grazes on tough encrusting coralline algae and organic biofilms from rock surfaces using its specialized chewing apparatus, known as Aristotle's lantern. - **Age differences:** Larvae are planktonic and feed on microscopic phytoplankton, while adults transition to grazing on sessile rocky algae. - **Primary Foods:** Coralline algae, Encrusting algae, Microscopic biofilms - **Foraging Method:** Grazing ## Ecological connections - **Hunts:** [Coralline Algae](https://www.snappit.app/explore/coralline-algae) (*Lithophyllum kotschyanum*) — Grazes upon this encrusting coralline alga as its primary food source on rocky shores. - **Eaten by:** [Wandering Tattler](https://www.snappit.app/explore/wandering-tattler) (*Tringa incana*) — Forages on exposed intertidal reefs during low tide, feeding on urchins and other invertebrates. ## Safety **Danger:** 1/5 · Very low No special safety notes yet. ## Frequently Asked Questions ### How to identify Shingle Urchin? Look for fins, arms, tentacles, shells and body symmetry. Underwater light shifts colors, so structure and markings usually matter more than shade. Sea Creature Identifier: upload a photo and compare the visible details. ### How long is Shingle Urchin? 5-8 cm ### How much does Shingle Urchin weigh? 0.05-0.15 kg ### How long does Shingle Urchin live? 5-10 years ### What does Shingle Urchin eat? Grazes on tough encrusting coralline algae and organic biofilms from rock surfaces using its specialized chewing apparatus, known as Aristotle's lantern. ### Where is Shingle Urchin usually found? Found on wave-beaten rocky intertidal shores, particularly on basaltic lava rocks exposed to heavy surf. ### How does Shingle Urchin hunt? Grazing ### How many eggs does Shingle Urchin lay? 10000-50000 ## Where to spot - [Allerton Garden](https://www.snappit.app/guides/places/allerton-garden) — Hawaii, US · Botanical Garden - [Kahanu Garden](https://www.snappit.app/guides/places/kahanu-garden) — Hawaii, US · Botanical Garden - [Lahaina Historic District](https://www.snappit.app/guides/places/lahaina-historic-district) — US · Historic District - [Lapakahi State Historical Park](https://www.snappit.app/guides/places/lapakahi-state-historical-park) — Hawaii, US · Historic District [View all places to see Shingle Urchin](https://www.snappit.app/guides/where-to-see/shingle-urchin) ## More Animal - [Coquina](https://www.snappit.app/explore/coquina) (*Gymnoscelis coquina*) - [Crystal Jelly](https://www.snappit.app/explore/crystal-jelly) (*Aequorea forskalea Péron &*) - [Nautilus](https://www.snappit.app/explore/nautilus) (*Nautilus*) - [Sea Anemone](https://www.snappit.app/explore/sea-anemone) (*unclassified Amphianthus (in: sea anemones)*) --- Source: [Shingle Urchin: Facts & Places to See — Snappit](https://www.snappit.app/explore/shingle-urchin)