Hawaii hermit crabs not in my book

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Some interesting hermit crabs not in Hawaii's Sea Creatures
The Bishop Museum's complete list of all hermit crabs & relatives known in Hawaii is here

Photo: Jeff Hill

REVI HERMIT CRAB
Calcinus revi Poupin & McLaughlin, 1998
     Exploring tide pools in Kailua-Kona on the Big Island, Jeff Hill found several tiny, almost all-white hermits which he could not identify. They had dark tips to the legs and a dark ocular peduncle (eyestalk). Searching the web, Jeff found something that looked like his hermits on a website run by Dr. Joseph Poupin--a little crab called Calcinus revi, known from French Polynesia and Japan. Jeff sent photos to several experts but no one was able to confirm the ID from photos alone. Eventually, he preserved a few specimens in vodka and sent them to Dr. Patsy McLaughlin in Washington State, who confirmed that one, an apparently mature male, did indeed match up to the published description of Calcinus revi, making this a new record for Hawaii. (The other specimen was a juvenile and not examined.)
     By amazing coincidence, right while all this was going on, Bob Kern sent me the photo below of a small white hermit he had photographed some years ago off Oahu, which could be Calcinus revi as well. Bob does not recall exactly where he took the photo, but it might have been in a tide pool at Pupukea.
     I notified Dr. Poupin of all this and he wrote back that he considered these developments to be most interesting. He added that the supposed Japanese record for C. revi has turned out to be a misidentified juvenile Calcinus elegans and that this finding may raise questions about the validity of revi as a species, even though the original specimens were from Fangataufa Atoll, French Polynesia. (Juvenile hermit crabs, which often have different coloration from the adults, have fooled experts before.) Although his records say that he has a specimen of an ovigerous female revi, proving that this tiny hermit is fully grown and not a juvenile, he cannot now locate the specimen. He would very much like to see another female bearing eggs in order to settle the issue for sure. Jeff, there's a mission for you!

Photo: Bob Kern

photo: Cory Pittman

HOOVER'S HERMIT CRAB
Catapaguroides hooveri McLaughlin & Pittman, 2002
Cory Pittman found several specimens of this tiny, colorful, fast-moving hermit crab in sand-dwelling Halimeda beds off West Maui in 1998 and 1999. He sent them to hermit crab specialist Pat McLaughlin for identification and they turned out to be an undescribed species. In 2002 Pat and Cory published a description of this animal in the journal Pacific Science, generously naming it after me. Handsome devil, isn't he? Cory has found these guys only in sand patches between clumps of the seaweed Halimeda, where, he writes, it is by far the most abundant hermit. (In the weed itself other species are more common.) He also reports that it "frequently abandons its shell and runs off if handled roughly" and that "it appears to be fairly indiscriminate in its choice of shells, sometimes even using segments of crustacean molts, hollowed-out segments of Halimeda, or other 'atypical' subsitutes." This photo, taken by Cory Pittman, is a tub-shot of a captured specimen.
Can't wait to read more? See McLaughlin PA and Pittman C, 2002. Reinstatement and rediagnosis of Catapaguroides setosus and description of a second Hawaiian species of the genus (Decapoda: Anomura: Paguridea: Paguridae) Pacific Science 56(1): 41-48.

Photo: Bob Kern

ISABEL'S HERMIT CRAB
Calcinus isabellae Poupin 1997

Bob Kern photographed this spectacular little hermit crab in July 2003 in front of the Firehouse at Pupukea Beach Park, O`ahu at a depth of 30-40 ft.along the wall. I sent the image to three experts, Dr. Patsy A. McLaughlin in Washington State, Joseph Poupin in France, and Gustav Paulay in Florida. All identified it immediately as this species, known up to now only from French Polynesia and the Mariana Islands. Dr. Poupin also mentioned that it is named after his wife!

Congratulations, Bob, on the first Hawaiian record of a very pretty little crab. If you read French and would like more details about this hermit see Zoosystema 19(4): 683-719, Poupin, J., Les pagures du genre Calcinus en Polynesie francaise avec la description de trois nouvelles especes (Decapoda, Anomura, Diogenidae].

Note: As of March 2006 Bob and Tina Owens have found and photographed several of these off Kona and Jeffrey Hill recently found one as well. In August 2007 I found half a dozen of them in one head of Cauliflower Coral not far off the beach at Honokohau, in Kona.

Dardanus brachyops Forest, 1962
family Diogenidae
This large, deep-water hermit crab is described in Spencer Tinker's out-of print book, Pacific Crustacea, published in 1965. Tinker writes:
     "This beautiful crustacean is the second largest hermit crab in Hawaii and one of the world's rarest. The upper parts of the body are buff or creamy-white in color, the carapace is marked with darker orange areas and lines, and the under surface of the body and legs is almost white in color. The legs of this crab are covered over their upper and outer surfaces with spines and tufts of stiff orange hair. The chelipeds are tipped with black, and the walking legs likewise terminate in a black-tipped claw. The antennae are a bright orange-red color. The body of this crab measures more than 8 in. in length.....
     At present this crab is known to occur only in Hawaii and Madagascar, although it undoubtedly occurs over much of the intervening area.
     This crab is rarely seen because it inhabits the deeper water on the outside of the reef. Specimens from Hawaii are usually captured at depths beyond 100 ft., and the single specimen from Madagascar was captured at about 250 ft. This species inhabits shells of the genus Tonna which it decorates with anemones, Calliactis armatus Verrill...."
Note: This hermit is regularly found in deep lobster traps in the Northwest Hawaiian Islands and, at least in Hawai`i, is not as rare as Tinker indicates.

NOTE: This and two crabs below were collected by Robert B. Moffitt from lobster traps set in the Northwest Hawaiian Islands. Depths were several hundred feet.

Dardanus sp.
family Diogenidae
This hermit crab has not yet been identified.

Ciliopagurus hawaiiensis (McLaughlin & Bailey-Brock, 1975)
family Diogenidae
Tthis beautiful hermit was described as Trizopagurus hawaiiensis in Pacific Science, vol. 29, no. 3, pp. 259-266. 1975. It is similar to C. strigatus, a species which often inhabits cone shells and has a conspicuously flattened carapace that fits the compressed space of the shell. As an interesting side note, the article states that one of the authors kept a specimen of C. hawaiiensis an aquarium for over a year and made observations on its behavior, feeding habits, and growth rates. It lived in a Terebra gouldi shell, which has a round rather than a flat opening. "Examination of this specimen after preservation revealed no dorso-ventral flattening of the carapace. In contrast, specimens of this species collected and preserved in their shells of Xenophora tenuis did exhibit varying degrees of dorsoventral compression. These observations lend support to Forest's proposition that the marked degree of carapace compression seen in some species of Trizopagurus is more a function of habitat than a genetic trait."