Sea Urchins

Phylum Echinodermata

Class Echinoidea

Sea Urchins

For more information about sea urchins visit Dr. Dafni's research page.

HAWAII

Heterocentrotus mammillatus

Blowhole, Oahu, Hawaii, 10 feet	Blowhole, Oahu, Hawaii, 25 feet
Palea Point, Oahu, Hawaii, 25 feet	Lanai Lookout, Oahu, 35 feet
Sea Cave, Oahu, 45 feet	Kapoho tidepool, Hawaii
Kapoho tidepool, Hawaii	Kapoho tidepool, Hawaii
Honokohau, Hawaii, 10 feet	Honokohau, Hawaii, 10 feet

SLATE PENCIL URCHIN

Locally abundant in shallow water. Spine shape and color varies throughout the islands. Night coloration is pale brown with lighter bands. Overall diameter is 10 inches.

Actinocidaris thomasi

Pitt Stop, Midway Atoll, 50 feet	Sharks Cove, Oahu, 30 feet
Sea Cave, Oahu, 50 feet

THOMAS' URCHIN

Rarely found in caverns at scuba depths. Spines are finely granulated. Overall diameter of 6 inches.

Prionocidaris hawaiiensis

Molokini Back Wall, Maui, 60 feet	Sea Cave, Oahu, 75 feet
Sea Cave, Oahu, 75 feet	Sea Cave, Oahu, 75 feet
Sea Cave, Oahu, 75 feet

ROUGH-SPINED URCHIN

Uncommon at scuba depths. More common among Finger Corals on Hawaii. Spines have large curved spines. Overall diameter of 10 inches.

Eucidaris metularia

Okoe Bay, Hawaii, 50 feet	Haleiwa Trench, Oahu, 50 feet
Atlantis Reef, Oahu, 95 feet

TEN-LINED URCHIN

Abundant under rocks at scuba depths. Overall diameter of 1.5 inches.

Astropyga radiata

Kihei, Maui	Kihei, Maui
Juvenile, Auau Crater, Hawaii, 180 feet

BLUE-SPOTTED URCHIN

Rarely found at scuba depths. Has tiny neon blue spots on test. To at least 4 inches.

Colobocentrotus atratus

Puako, Hawaii	Makapu'u, Oahu, Hawaii
Makapu'u, Oahu, Hawaii	Makapu'u, Oahu, Hawaii
Lanai Lookout, Oahu	Makapu'u, Oahu, 1 foot
Makapu'u, Oahu, 1 foot

SHINGLE or HELMET URCHIN HA'UKE'UKE

Abundant intertidally on surf-swept cliffs. Diameter is 3 inches.

Tripneustes gratilla

Puako, Hawaii, 30 feet	Ft. Kamehameha, Oahu, 4 feet
Sharks Cove, Oahu, 40 feet	Sharks Cove, Oahu, 40 feet
Lanai Lookout, Oahu, 25 feet	Hanauma Bay, Oahu, 35 feet
Sea Cave, Oahu, 60 feet	Honokohau, Hawaii, 10 feet
Honokohau, Hawaii, 10 feet	Honokohau, Hawaii, 10 feet

COLLECTOR URCHIN

Common in shallow water. Spines range from white to black; test is dark and inflated.

Pseudoboletia indiana

Punalu'u, Hawaii, 8 feet	Punalu'u, Hawaii, 8 feet
Kewalo, Oahu, Hawaii, 50 feet	Kewalo, Oahu, Hawaii, 50 feet
Kewalo, Oahu, Hawaii, 50 feet	Kewalo Pipe, Oahu, 50 feet
Kewalo Pipe, Oahu, 50 feet	Lanai Lookout, Oahu, 45 feet

PEBBLE-COLLECTOR URCHIN

Uncommon partially buried in gravel. Spines range from white to purple; test is white and compressed. About 5 inches.

Cyrtechinus verruculatus

Makapu'u tidepool, Oahu

WARTY SAND URCHIN

A tiny species found under rocks but often overlooked. Less than 1 inch.

Diadema paucispinum

Molokini Back Wall, Maui, 60 feet	Kailua Pier, Kona, Hawaii, 8 feet
Ka'ohe, Kona , Hawaii, 10 feet	Juvenile, Sea Tiger, Oahu, 85 feet
Molokini, 75 feet	Molokini, 75 feet

LONG-SPINED URCHIN

Uncommon along steep dropoffs. Test is 2-3 inches in diameter. Primary spines are extremely long and fragile. Has thinner venomous spines protected by long primary spines. Hawaii & the South Pacific. Keys to identification of worldwide Diadema & Echinothrix

Diadema sp.

Midway Harbor, 10 feet

Midway Harbor, 10 feet

Midway Harbor, 10 feet

Midway Harbor, 10 feet

RED LONG-SPINED URCHIN

One of two red diadematids from Midway lagoon. Has short, thin venomous spines protected by large primary spines.

Echinothrix calamaris

Blowhole, Oahu, 25 feet	Palea Point, Oahu, 40 feet
Sharks Cove, Oahu, 25 feet	Blowhole, Oahu, 20 feet
Makapu'u tidepool, Oahu	Juvenile, Kewalo, Oahu, Hawaii, 25 feet
Lanai Lookout, Oahu, 30 feet	Kewalo, Oahu, 40 feet
Kewalo, Oahu, 40 feet	Sea Tiger Wreck, Oahu, 95 feet
YO-257 Wreck, Waikiki, Oahu, 85 feet	Puako, Hawaii, 35 feet
Honokohau, Hawaii, 30 feet	Honokohau, Hawaii, 30 feet

BANDED URCHIN

Common in shallow water to at least 60 feet. Overall diameter is 8 inches. Has thinner venomous spines protected by large primary spines. Black occasionally banded with white. Anal opening may host the commensal crab, Echinoecus pentagonus. Hawaii & the Indo-Pacific.

Echinothrix diadema

Kahe Point, Oahu, 15 feet	Kaiwi Point, Hawaii, 4 feet
Juvenile, Kaunolu Bay tidepool, Lana'i	Kahe Point, Oahu, 15 feet
Spawning, Makapu'u tidepool, Oahu	Makapu'u tidepool, Oahu
Spawning, Ft. Kamehameha, Oahu, 3 feet	Spawning, Ft. Kamehameha, Oahu, 3 feet
Juvenile, Makapu'u tidepool, Oahu	Juvenile, Makapu'u tidepool, Oahu
Sea Cave, Oahu, 35 feet	Kahuku, Oahu

BLUE-BLACK URCHIN

Common in shallow water exposed to wave action. Overall diameter is 8 inches. Black with blue iridescence, juveniles banded with blue. Has thinner venomous spines protected by large primary spines. Hawaii & the Indo-Pacific.

Leptodiadema purpureum

Shark's Cove, Oahu, Hawaii, 25 feet	Moku Manu, Oahu, Hawaii, 40 feet

FINE-SPINED URCHIN

Rare in deep caves. Test is less than 1 inch in diameter. Spines are glasslike. Moves rapidly away from light.

Echinometra mathaei

Keahole Point, Hawaii, 2 feet	Makai Pier, Oahu, Hawaii, 8 feet
Borings in basalt, Makapu'u, Oahu, Hawaii	Kaunolu Point tidepool, Lana'i, Hawaii
Haleiwa Trench, Oahu, 5 feet	Ft. Kamehameha, Oahu, 3 feet
Makapu'u tidepool, Oahu	Makapu'u tidepool, Oahu
Juvenile, Makapu'u tidepool, Oahu	Kahuku, Oahu
Kahuku, Oahu

PALE ROCK-BORING URCHIN

Abundant at all depths. Ranges from pink to olive; never black. Spines are strong and sharp. Overall diameter is 3 inches.

Echinometra oblonga

Puako, Hawaii, 20 feet

With parasitic Vexilla snail, Makapu'u, Oahu

Makapu'u tidepool, Oahu

BLACK ROCK-BORING URCHIN

Common in shallow water. Always black. Spines are strong but not sharp. Overall diameter is 3 inches.

Echinostrephus aciculatus

Kaena Point, Oahu, 50 feet	Keoki's Ledge, Midway Atoll, 30 feet
Kahe Point, Oahu, 25 feet	Waimea Bay, Oahu, 30 feet
Sharks Cove, Oahu, 30 feet

NEEDLE-SPINED URCHIN

Abundant at scuba depths. Ranges from purple to black. Spines are thin and sharp. Overall diameter is 3 inches.

Brissus latecarinatus

Firehouse, Oahu, 35 feet	Firehouse, Oahu, 35 feet
Kewalo Hump, Oahu, 90 feet	Kewalo Hump, Oahu, 90 feet
Puu Kala Point, Kona, Hawaii, 60 feet

HEART URCHIN

Uncommon buried deep in sand at any depth. Reaches at least 8 inches.

Echinocyamus sp.

Kahe Point, Oahu, Hawaii	Kahe Point, Oahu, Hawaii

MINIATURE HEART URCHIN

Empty tests are common in sand while live animals are difficult to find. Several species in Hawaii. About 3/8 inch.

Clypeaster reticulatus

Sea Tiger, Oahu, 120 feet	Sea Tiger, Oahu, 120 feet

RETICULATED SEA BISCUIT or CAKE URCHIN

Empty tests are occasionally found, live animals emerge from sand at night to feed. About 1 inch. Hawaii & the Indo-Pacific.

INDO-PACIFIC

Toxopneustes pileolus

Yawatano, Izu, Japan

Yawatano, Izu, Japan

FLOWER URCHIN

Locally common on rubble and sand at scuba depths. Cup-like pedicellariae deliver a powerful sting that can be fatal. About 5 inches. Indo-West Pacific.

Asthenostoma ijimai

MAGNIFICENT SEA URCHIN

TROPICAL EASTERN PACIFIC

URCHIN

NORTHEAST PACIFIC

Strongylocentrotus droebachiensis

Ogden Point, Victoria, Canada, 5 feet	Ogden Point, Victoria, Canada, 5 feet

GREEN SEA URCHIN

Common on rocks or sand at any depth. About 4 inches. Circumpolar distribution, south to Japan and Washington.

Strongylocentrotus franciscanus

Rock Quarry, Catalina, California, 25 feet

RED SEA URCHIN

Common in crevices at any depth. About 10 inches. Red to black. Primary species harvested for roe. Japan to Alaska and outer Baja California.

Strongylocentrotus purpuratus

Rock Quarry, Catalina, California, 5 feet

PURPLE SEA URCHIN

Common under rocks and in crevices in shallow water. About 3.5 inches. Alaska to Outer Baja California.

Centrostephanus coronatus

Rock Quarry, Catalina, California, 25 feet

CROWNED SEA URCHIN

Very common on rocks and in crevices. Spines about 7 inches. Southern California & Tropical Eastern Pacific..

Lytechinus anamesus

Emerald Bay, Catalina, California, 25 feet

Emerald Bay, Catalina, California, 25 feet

WHITE SEA URCHIN

Common on sand and rubble at any depth. About 3 inches. Southern California to Baja California.

CARIBBEAN

Meoma ventricosa

Paradise Cove, Grand Bahama Island, 4 feet

SEA BISCUIT

Common on sand flats and grass beds in shallow water. About 8 inches.

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