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Phylum
Arthropoda
Crabs
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Crabs are decapods having 5 pairs of legs. Hawaii
has nearly 200 species in a multitude of families and positive
identification is often difficult for the untrained. Much of the
literature available is old. Length indicated refers to carapace
(shell) width.
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Megalops Larval Stage |
HAWAII
Family Galatheidae
Squat Lobsters
Galathea sp.
Sea Cave, Oahu, 80 feet |
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SQUAT LOBSTER
| Tiny crabs
that inhabit cracks & crevices on reefs. Difficult to
identifiy due to their small size. Attains 1cm. |
Family Porcellanidae
Porcelain Crabs
Petrolisthes coccineus
Sharks Cove, Oahu, 30 feet
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Sharks Cove, Oahu, 30 feet |
Sharks Cove, Oahu, 30 feet |
Sharks Cove, Oahu, 30 feet |
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RED PORCELAIN CRAB
| Uncommon under
stones in shallow water. Stirs up sediment and strains bits of
organic matter using elongated hairs on its mouth parts. Carapace
width less than 1 inch. Hawaii & the Indo-Pacific. |
Family Hippidae
Mole Crabs
Hippa pacifica
Waimanalo Beach, Oahu |
Waimanalo Beach, Oahu |
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PACIFIC MOLE CRAB
| Common in sand along water's edge of wave-washed beaches. Feeds
upon Portuguese Man-o-war.
About 1 inch long. |
Family Dromiidae
Sponge Crabs
Dromia dormia
Nanahoa, Lana'i, 30 feet
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Kahekili Point, Maui |
Kahekili Point, Maui
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SLEEPY SPONGE CRAB
| Uncommon under ledges and in caverns. Holds onto large sponges
with hind legs. About 8 inches wide. Not edible. |
Family Raninidae
Ranina ranina
Kailua-Kona, Hawaii
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Kailua-Kona, Hawaii |
Makua, Oahu, 30 feet
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Makua, Oahu, 30 feet |
Makua, Oahu, 30 feet |
Makua, Oahu, 30 feet |
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KONA CRAB
| Uncommon on sandy flats at scuba depths. Remains buried except
for the eye stalks. Up to 9 inches long. Excellent eating. |
Family Majidae
Spider Crabs
Schizophroida hilensis
Makapu'u tidepool, Oahu |
Makaha, Oahu, 25 feet
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Makapu'u tidepool, Oahu
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Wailupe, Oahu, 3 feet |
Wailupe, Oahu, 3 feet |
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| Occasional under rocks and on vertical surfaces. Less than 1 inch. |
Simocarcinus simplex
Makapu'u tidepool, Oahu
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Makapu'u tidepool, Oahu |
Makapu'u tidepool, Oahu |
Makapu'u tidepool, Oahu
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SIMPLE COLLECTOR CRAB
| Uncommon on frondose seaweeds in shallow water. About 1
inch. Brown or Green, shell longer in males. Hawaii and the
Indo-Pacific.. |
Family Calappidae
Box Crabs
Calappa calappa
Sharks Cove, Oahu, 35 feet
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Makua, Oahu, 20 feet
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Makua, Oahu, 20 feet |
Makua, Oahu, 20 feet
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Makua, Oahu, 20 feet |
Makua, Oahu, 20 feet
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Makua, Oahu, 20 feet |
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SMOOTH BOX CRAB
| Uncommon in sand at scuba depths.
Normally buried with only the eye stalks extended. May be covered
with dark spots. Attains 6 inches. Hawaii & the
Indo-Pacific. |
Calappa
gallus
 Koko
Craters, Oahu, 35 feet
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KNOBBY BOX CRAB
| Lives among
rubble and difficult to spot. Covered with large nodules and the
claws have a strongly serrated upper margin. About 2.5 inches wide.
Hawaii & the Indo-Pacific. |
Calappa hepatica
Makai Pier, Waimanalo, Oahu, 20 feet
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Kaneohe Bay Sandbar, Oahu, 5 feet |
Kaneohe Bay Sandbar, Oahu, 5 feet
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Kaneohe Bay Sandbar, Oahu, 5 feet |
Juvenile, Sharks Cove, Oahu, 40 feet
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Juvenile, Firehouse, Oahu, 30 feet |
Juvenile, Firehouse, Oahu, 30 feet
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Sea Tiger, Oahu, 120 feet |
Sea Tiger, Oahu, 120 feet
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Sea Tiger, Oahu, 120 feet |
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BOX CRAB
| Common in sand in shallow water. About 2-3 inches wide.
Most common member of the genus. |
Family Leucosiidae
Nucia speciosa
Haleiwa Trench, Oahu, 25 feet |
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| Uncommon at night. Less than 3/4 inch wide. |
Actaeomorpha erosa
Makapu'u tidepool, Oahu |
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| An uncommon 3/4 inch crab from shallow water. |
Family
Grapsidae
Rock Crabs
Grapsus tenuicrustatus
Kaka'ako, Oahu |
Kaunolu Bay tidepool, Lana'i
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Hickam AFB, Oahu |
Hickam AFB, Oahu
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Kaupo tidepool, Oahu
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Kaupo tidepool, Oahu |
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THIN-SHELLED ROCK CRAB
'A'AMA
| Abundant on rocks in the splash zone. Carapace width 2 inches. |
Grapsus
longitarsus
Makapu'u, Oahu |
Makapu'u, Oahu
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Kapoho Point, Kailua, Oahu |
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LONG-LEGGED ROCK CRAB
| Occasional on rocks in shallow water. About 2 inches wide. |
Plagusia depressa
Ft. Kamehameha, Oahu, 1 foot |
Ft. Kamehameha, Oahu, 1 foot
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Ft. Kamehameha, Oahu, 1 foot |
Ft. Kamehameha, Oahu, 1 foot
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Ft. Kamehameha, Oahu, 1 foot |
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SCALY ROCK CRAB
| Common just below the waterline on rocky shores. About 2 inches. |
Percnon abbreviatum
Firehouse, Oahu, 25 feet
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ABBREVIATED ROCK CRAB
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Uncommon under stones. Up to 2 inches wide.
Hawaii & the Indo-Pacific. |
Percnon affine
Female, Sharks Cove, Oahu, 30 feet
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Male, Sharks Cove, Oahu, 30 feet |
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BLUE-EYED ROCK CRAB
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Occasional in holes and caverns in shallow
water. Eyes are bright blue. Up to 3 inches wide.
Hawaii & the Indo-Pacific. |
Percnon
planissimum
Sharks Cove tidepool, Oahu |
Makapu'u tidepool, Oahu
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Night, Makapu'u tidepool, Oahu
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Sharks Cove, Oahu, 25 feet |
Kaloko, Oahu, 5 feet |
Kaloko, Oahu, 5 feet |
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FLAT ROCK CRAB
| Common under boulders at in shallow water. Neon green lines are
outstanding. About 1inch wide. |
Metopograpsus
thukuhar
Male, Moku O Loe, Kaneohe Bay, Oahu, 1 foot |
Female, Moku O Loe, Kaneohe Bay, Oahu, 1 foot |
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| Uncommon on rocks and mangroves in shallow water. Carapace 2 inches
wide. |
Planes
cyaneus
Waimanalo Beach, Oahu |
Waimanalo Beach, Oahu |
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FLOTSAM or BLUE PACIFIC WEED CRAB
| Lives attached to floating objects & turtles in the open ocean and washed ashore
during storms. Carapace 1/3 inch
wide. Pacific Ocean. |
Family Parthenopidae
Parthenope sp.
Makai Pier, Oahu, 10 feet |
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| Rare in sand and silt in shallow water. Carapace about 1 inch wide.
Possibly Parthenope hoplonotus. |
Family Ocypodidae
Ghost Crabs
Ocypode pallidula
Eating Portguese Man-o'-war, Waimanalo Beach, Oahu |
Ft. Kamehameha, Oahu |
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PALLID GHOST CRAB
| Common on sandy beaches and active during the day. About 1 inch
wide. |
Ocypode
ceratophthalma
Makai Pier, Oahu
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Waimanalo Beach, Oahu |
Diamond Head, Oahu |
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HORN-EYED GHOST CRAB
| Common on sandy beaches after dark. Burrows can be identified by
the conical piles of sand at the entrance. About 1.5 inches wide. |
Family Palicidae
Crossotonotus spinipes
Moku O Loe, Kaneohe Bay, Oahu, 3 feet |
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| Occasional in shallow water at night. About 1 inch wide. |
Exopalicus maculatus
Haleiwa Trench, Oahu, 30 feet
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| Uncommon on reefs at night. About 1 inch. Hawaii & the
Indo-Pacific. |
Family Portunidae
Swimming Crabs
| Swimming crabs have paddle-shaped tips on their hind legs and are very
agile. Many species are edible including the Blue Crab. |
Charybdis erythrodactyla
Blowhole, Oahu, 20 feet
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Blowhole, Oahu, 40 feet
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Blowhole, Oahu, 40 feet
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Blowhole, Oahu, 40 feet
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Sharks Cove, Oahu, 25 feet |
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RAINBOW SWIMMING CRAB
| Uncommon in dark holes and crevices. About 3 inches wide. |
Charybdis
hawaiensis
Haleiwa Trench, Oahu, 20 feet |
Haleiwa Trench, Oahu, 20 feet |
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HAWAIIAN SWIMMING CRAB
| Common at scuba depths in holes and within Antler
coral.
About 3 inches wide. |
Gonioinfradens
paucidentata
Sharks Cove, Oahu, 25 feet |
Firehouse, Oahu, 45 feet |
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RED SWIMMING CRAB
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Uncommon at scuba depths in caverns. Carapace
teeth are tipped with black. Up to 4 inches wide. Hawaii
& the Indo-Pacific.
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Carupa tenuipes
Makapu'u tidepool, Oahu |
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VIOLET-EYED SWIMMING CRAB
| Occasional in shallow water at night. About 1 inch wide. |
Lissocarcinus orbicularis
Okoe Bay, Hawaii, 90 feet |
Molokini, Maui, 60 feet |
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SEA CUCUMBER CRAB
| Occasional within the gut cavity of large sea
cucumbers. Less
than 3/4 inches wide. |
Podphthalmus vigil
Kuapa Pond, Hawaii Kai, Oahu |
Kuapa Pond, Hawaii Kai, Oahu |
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LONG-EYED SWIMMING CRAB
| Lives in mud and silty sand burrows in bays, harbors, fishponds, and
estuaries but rarely seen by divers. About 5 inches.
Indo-Pacific. |
Portunus longispinosus
Punalu'u, Oahu, 3 feet
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Makapu'u, Oahu, 2 feet |
Moku O Loe, Kaneohe Bay, Oahu, 1 foot |
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LONGSPINED PORTUNID
| Common in sandy rubble in shallow water. About 1 inch wide. |
Portunus pubescens
Punalu'u, Oahu, 3 feet |
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HAIRY PORTUNID
| Uncommon in sand & rubble at night. About 2 inches wide. |
Portunus sanguinolentus
Osezaki, Izu, Japan, 30 feet |
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BLOOD-SPOTTED SWIMMING CRAB
| Common in muddy sand in deeper water. Hawaiian crabs are an
endemic subspecies. About 6 inches wide. |
Scylla serrata
Bellows Beach, Oahu |
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MANGROVE OR SAMOAN CRAB
| Common in brackish water and muddy nearshore waters.
Width to at least 10 inches. Large claws are capable of causing
serious injury. Introduced to Hawaii. |
Thalamita
crenata
 Kuliouou, Oahu, 1 foot |
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NOTCHED SWIMMING CRAB
| Common in shallow silty environments. Attains 4 inches in
width. Indo-Pacific. |
Thalamita
coerulipes
Kapoho Point, Kailua, Oahu, 1 foot |
Kapoho Point, Kailua, Oahu, 1 foot |
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| Occasional under rocks in shallow water. About 1 inch wide. |
Thalamita edwardsi
Moku O Loe, Kaneohe Bay, Oahu, 2 feet
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Makapu'u tidepool, Oahu |
Makapu'u tidepool, Oahu |
Kaupo tidepool, Oahu |
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| Common on reefs in shallow water. About 1.5 inches. |
Family Carpiliidae
Carpilius maculatus
Sharks Cove tidepool, Oahu |
Kahuwai, Kona, Hawaii, 30 feet |
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SEVEN-ELEVEN CRAB
| Occasional in holes at scuba depths. To at least 8 inches wide. |
Carpilius convexus
Makapu'u tidepool, Oahu
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Makapu'u tidepool, Oahu |
Mating, Makapu'u tidepool, Oahu |
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CONVEX CRAB
| Occasional in crevices of shallow reefs exposed to wave action.
About 4 inches wide. |
Family Xanthidae
Typical Crabs
| Xanthids have pointed hind legs and inhabit rocky reefs. Many
species are known to be poisonous and should not be eaten. |
Lybia
edmondsoni 
Black Rock, Maui, 30 feet |
Kewalo Pipe, Oahu, 50 feet |
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HAWAIIAN POM-POM CRAB
| Occasional under rocks in shallow water. Holds the venomous anemone
Triactis producta for defense. Endemic to Hawaii. |
Polydectus cupulifer
Ma'ili Point, Oahu |
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TEDDY-BEAR CRAB
| Uncommon under rock in shallow water. Holds the anemone
Telmatactis decora in its claws for defense. About 3/4 inch
wide. |
Liomera rubra
Haleiwa Trench, Oahu, 60 feet |
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RED LIOMERA
| Uncommon under rocks at scuba depths. Less than 3/4 inch wide. |
Lophozozymus pulchellus
Makapu'u tidepool, Oahu |
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| Uncommon under rocks at night in shallow water. About 1 inch. |
Pilodius areolatus
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Kapoho Point, Kailua, Oahu
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Kapoho Point, Kailua, Oahu |
Moku O Loe, Kaneohe Bay, Oahu, 3 feet
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Kaupo tidepool, Oahu
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AREOLATED CRAB
| Very common on shallow reefs at night. About 1.5 inches wide. |
Platypodia eydouxii
Makapu'u tidepool, Oahu |
Makapu'u tidepool, Oahu |
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| Occasional under stones in shallow water. About 1.5 inches wide. |
Etisus splendidus
Shipwreck Beach, Lana'i, 60 feet |
Baby Barge, Kahala, Oahu, 60 feet
photo by Gabe Scotti, owner of
www.kaimanadivers.com
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SPLENDID PEBBLE CRAB
| Uncommon on reefs at scuba depths at night. About 6 inches wide. |
Tweedieia laysani
Horseshoe Reef, Oahu |
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| First described from Hawaii. About 1 inch. |
Xanthias latifrons
Sharks Cove, Oahu |
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| Occasionally seen at night. About 3/4 inch in width.
Hawaii & the Indo-Pacific. |
Family Trapeziidae
Coral Crabs
Trapezius flavopunctata
Blowhole, Oahu, 40 feet |
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YELLOW-SPOTTED GUARD CRAB
Trapezius intermedia
Makapu'u tidepool, Oahu |
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COMMON GUARD CRAB
Family Cryptochiridae
Coral Gall Crabs
Utinomiella dimorpha
Sea Tiger, Oahu, 85 feet |
Sea Tiger, Oahu, 85 feet |
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CAULIFLOWER CORAL CRAB
INDO-PACIFIC
Hoplophrys
oatesii
Wakatobi, Indonesia, 25 feet |
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SOFT
CORAL CRAB
| Uncommon on soft corals. Not found in Hawaii. About 1/5
inch wide. |
Xenocarcinus tuberculatus
Wakatobi, Indonesia, 150 feet |
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WIRE CORAL CRAB
| Found on wire corals in the Indo-Pacific except Hawaii. About 1
inch long. |
NORTHEAST PACIFIC
 
Family Majidae
Spider Crabs
Hyas lyratus
Spring Bay, Victoria, Canada, 20 feet
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PACIFIC LYRE CRAB
| Found at any depth with Oregonia gracilis. Up to 3 inches
tall. Alaska to Puget Sound. |
Pugettia producta
Spring Bay, Victoria, Canada, 20 feet
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Spring Bay, Victoria, Canada, 20 feet |
Spring Bay, Victoria, Canada, 20 feet
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NORTHERN KELP CRAB
| Common on kelp and pilings in shallow and deep water. About 3.5
inches wide. Alaska to Baja California. |
Oregonia
gracilis
Spring Bay, Victoria, Canada, 20 feet
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Spring Bay, Victoria, Canada, 20 feet |
Spring Bay, Victoria, Canada, 20 feet
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Spring Bay, Victoria, Canada, 20 feet |
Spring Bay, Victoria, Canada, 20 feet
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Spring Bay, Victoria, Canada, 20 feet |
Spring Bay, Victoria, Canada, 20 feet
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Spring Bay, Victoria, Canada, 20 feet |
GRACEFUL DECORATOR CRAB
| Common at any depth, normally heavily decorated. Up to 1.5
inches long. Japan to Alaska and Monterey. |
Family Cheiragonidae
Telmessus cheiragonus
Spring Bay, Victoria, Canada, 20 feet
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Spring Bay, Victoria, Canada, 20 feet |
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HELMET CRAB
| Uncommon and skittish when approached. Inhabits heavy vegetation
and buries in sand. Up to 4 inches wide. Japan to Alaska and
Monterey, California. |
Family Cancridae
Cancer gracilis
Ogden Point, Victoria, Canada, 5 feet |
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GRACEFUL CRAB
| Common in sandy and muddy areas to very deep water. Attains 5
inches. Alaska to Baja California. |
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