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Related FAQs: Sea Urchins, Urchins 2Urchins 3Urchin Identification, Urchin Behavior, Urchin Compatibility, Urchin Selection, Urchin System, Urchin Feeding, Urchin Disease, Urchin Reproduction

Related Articles: Echinoderms, An Introduction to the Echinoderms:  The Sea Stars, Sea Urchins, Sea Cucumbers and More... By James W. Fatherree, M.Sc. Algae ControlNutrient Control and Export

/A Diversity of Aquatic Life

Some Spines Now! Sea Urchins (and Sand Dollars), the Echinoids, Pt. 4

To: Part 1, Part 2, Part 3, Part 5, Part 6

By Bob Fenner

Echinometra mathaei

Genus Echinometra:

Echinometra lacunter, the Rock-Boring Urchin. Dark colored with red highlights.  2-3 inches in diameter. Relatively short, pointed spines. Reddish centers. Tropical West Atlantic. 

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Echinometra mathaei (Blainville 1825), the Common Urchin. Indo-Pacific; Red Sea to Hawai'i. To about four inches overall diameter. Hides by day in rocky crannies it helps gouge. Mostly eats algae it rasps from rocks by night. In Oahu, Hawai'i by day.
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Echinometra viridis, the Reef Urchin. 2-3 in. diameter. Pointed purple to brownish spines with a white ring around their base. Tropical West Atlantic. Feed during the night (hide in coral, rock by day) on algae. Cozumel image. 

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Genus Echinostrephus:

Echinostrephus aciculatus Agassiz 1893, the Rock Boring Urchin. N. Sulawesi pic.

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Family Echinothuriidae: Pinhead Sea Urchins.

Asthenosoma varium Grube 1866, the Pinhead Sea Urchin. Family Echinothuriidae. Indo-West Pacific; Red Sea to Indonesia. Test size to six inches in diameter; spines to twelve. Nocturnal, not safe kept with other invertebrates. Walks on spines and/or tube feet. Takes all foods. This one in the Red Sea.

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Family Strongylocentrotidae:

An image to show you what cooler water Urchins can/do look like. The larger, redder individual in the upper part of the frame is the larger species, Strongylocentrotus sanfriscanus, the ones in the foreground are the more common, smaller Strongylocentrotus purpuratus. Both have their eggs used in the sushi bar business as uni.

To: Part 1, Part 2, Part 3, Part 5, Part 6

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