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Related FAQs: Hermit Crabs, Hermit Crabs 2Hermit Crabs 3, Hermit ID 1, Hermit IDs 2, Hermit IDs 3, Hermit IDs 4, & Hermit Behavior, Hermit Compatibility, Hermit Selection, Hermit Systems, Hermit Feeding, Hermit Reproduction, Hermit Disease/Health,
FAQs: By species:
Calcinus laevimanus (Zebra, Left-handed Hermit), Clibanarius tricolor (Blue-Legs), Clibanarius vittatus (a common Gulf of Mexico hermit crab), Dardanus megistos (Shell-Breaking Reef, White-spot, Fuzzy Leg Hermit Crab),  Paguristes cadenati (Scarlet, Red-Legged), Petrochirus diogenes (a and other Giant Hermit Crabs), & Anemone Hermits, Sponge/Staghorn/Coral house Hermits, Unknown/Wild-collected,
& Land Hermit Crabs, True Crabs, Marine Crab Identification, Micro-Crustaceans, Amphipods, Copepods, Mysids, Hermit Crabs, Shrimps, Cleaner Shrimps, Banded Coral Shrimp, Mantis Shrimp, Anemone Eating ShrimpMarine ScavengersCrustacean Identification, Crustacean Selection, Crustacean Behavior, Crustacean Compatibility, Crustacean Systems, Crustacean Feeding, Crustacean Disease, Crustacean Reproduction,
 

Related Articles: Squat Lobsters, Crustaceans, Marine Crabs, Freshwater to Brackish Crabs, Algae Control, Marine Maintenance, Reef Maintenance, Marine ScavengersNutrient Control and ExportMarine Scavengers

Hermit Crabs, Use in the Marine Aquarium Hobby

By Bob Fenner

 Reef Hermit, Calcinus tibicen

New Print and eBook on Amazon

Marine Aquarium Algae Control

by Robert (Bob) Fenner

To place the Hermit Crabs and their relatives in taxonomic perspective let's do a/the usual rundown on their systematics starting from the:

Subphylum Crustacea:   

About 42,000 species of some of the most familiar arthropods; crabs, shrimps, lobsters, crayfish, wood-lice (sow-bugs, rolly-pollies, you know, terrestrial isopods, and aquatic, even parasitic marine ones). Many small members in fresh and marine habitats of importance in aquatic food chains. Primarily aquatic, mostly marine.

Some common characteristics of the crustaceans: 1) Their heads are more or less uniform with five pair of appendages: they have two pair of antennae (this feature is distinctive within the phylum); the third pair as opposing, biting, grinding mandibles. Behind the mandibles there are two pair of accessory feeding appendages, the first and second maxillae. 2) Their bodies trunks are composed of distinct segments covered by a chitinous exoskeleton strengthened by deposition of calcium salts. 3) Crustacean appendages are typically biramous (two major elements). 4) They typically have a carapace covering the trunk of their bodies. Enough of this detail. We'll cover this stuff in more general survey pieces of the mega-groups. On toward the lobsters.

A systematic resume of the Crustacea is necessarily large and complex. Allow me to semi-skirt around a full discussion here. The nine Classes that don't include our family of interest enclose the primitive cephalocaridans (C. Cephalocarida), the Class Branchiopoda (fairy shrimps, tadpole shrimps, water fleas (Daphnia); the Class Ostracoda, Class Copepoda (Anchor worm, Lernaea), Classes Mystacocarida, Branchiura, Tantulocarida, Remipedia, Cirripedia (barnacles), whew! & finally, our:

Class Malacostraca

Comprises almost three-fourths of all described species of crustaceans and most of the larger forms, such as crabs, lobsters, and shrimps. Characteristics: Trunks typically composed of 14 segments plus the telson ("tail"); the first 8 segments form the thorax, the last 6 the abdomen; all segments bear appendages. Four Superorders: Syncarida, Hoplocarida, Peracarida, and the one we want to talk about, the Eucarida.

Superorder Eucarida contains many of the large malacostracans. They have highly developed carapaces displaying fusion of all thoracic segments (the cepahalothorax). Eyes are stalked... Two living orders; the Euphausiacea (krill) and the:

Order Decapoda includes the familiar shrimps, crayfish, lobsters and crabs. This is the largest order of crustaceans with @10,000 species. Decapods are distinguishable from euphausiaceans and other malacostracans in that their first three pair of thoracic appendages, The remaining five pairs are legs (Decapoda= "ten feet"). Decapods are further divided into two Suborders, the Dendrobranciata, with "tree-like" branched gills, body laterally compressed..., eggs planktonic, nauplius as the first larval stage (as in Artemia, our brine shrimp), Infraorders, Sections, Superfamilies... See Barnes re their higher taxonomy.

Of animals that are Crabs ("false" and true) there are about eight thousand described species, with about 600 venturing into or living in freshwater. 

Infraorder Anomura, families of Hermit Crabs, Sand or Mole Crabs, Crab-like Crustaceans. Depressed carapaces, third pair of legs never chelate, fourth and fifth pair reduced....  Have a soft abdomen... live with bodies enclosed in discarded shells for the most part.

  Superfamily Galatheoidea         

Family Chirostylidae

Family Galatheidae (squat lobsters)

Family Porcellanidae (porcelain crabs)

   Superfamily Hippoidea     

Family Albueidae (mole crabs)

          Family Hippidae (sand crabs)   Superfamily Paguroidea, have oval carapaces, usually asymmetrical. Live either in shells or with abdomen tucked underneath. First pair of legs as chelipeds. Includes the Hermit Crab genera: Pomatocheles, Petrochirus, Clibanarius, Coenobita (land Hermit Crab), Pagurus, Pylopagurus, Birgus (the Coconut Crab), Stone Crabs like Lithodes, Paralithodes (commercial King Crab of the North Pacific).

Family Aeglidae

Family Callianassidae (ghost shrimps)

Family Coenobitidae (land hermit crabs)

Family Ctenocheildae

Family Laomediidae

Family Lithodidae (stone and king crabs)

Family Lomidae

Family Paraguridae (deepwater hermit crabs)

Family Pylochelidae

Family Thalassinidae

Family Upogebiidae (mud shrimps) Aquarium Hermit Crabs:

Family Diogenidae (left-handed hermit crabs) and Family Paguridae (right-handed hermit crabs):  

Unusual find: a dead Hermit Crab found lying on coral in Fiji.

Best (most "Reef-Safe") Hermit Crab Species (though no carte-blanche guarantees) for Algae Control: Even these cannot be absolutely trusted with small fishes, invertebrates if hungry... and they too can be meals for... Puffers, Triggerfishes, Stomatopods (Mantis), Alpheids (Pistol Shrimp)...

Calcinus laurentae Haig & McLaughlin 1983, Laurent's Hermit Crab, Family Diogenidae. Orange-yellow antennae. Claw-limbs brown, other legs pink with white junctions and black tips.  Hawaiian endemic. Common. To about 1/5" carapace length. Kona pic.  

Verticals (Full/Cover Page Sizes Available
Calcinus tibicen, the Orangeclaw Hermit Crab, Family Diogenidae. Tropical West Atlantic. Orange antennae and eyestalks. Eye tips white, eyes with black pupils. Unequal size claws. 1/2 to 1". 

Clibanarius tricolor, the Blue-Legged Hermit Crab. To less than an inch in length. One of a few "reef-safe" Hermits that stay small and almost exclusively feed on algae (and Cyanobacteria!). Good for aiding in aerating the substrate as well. Aquarium photo. 

Clibanarius digueti, a Mexican Hermit Crab, aka the Blue-Eyed Spotted Hermit. To less than an inch in length.  

 

Clibanarius seurati

Fiji

Clibanarius vittatus, a common Gulf of Mexico hermit crab. Very hardy... can live out of water for days at times. "*C. vittatus* does get rather large, 10 cm at least (Adam J. said he had one (actually, he said it was *P. holthuisi* in a 6" shell)" Scott Allen Rauch pic.

Bigger PIX:
The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

Paguristes cadenati Forest 1954, the Scarlet or Red-Legged Reef Hermit. Tropical West Atlantic. To one inch in length. Red carapace and legs, eyes green, on yellow stalks. Aquarium and Cozumel photo.

Never entirely "reef safe"... All hermits are to degrees opportunistic omnivores... they WILL eat your other livestock if hungry... Here two Paguristes cadenati are "riding" a snail...

Bigger PIX:
The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.
  
Phimochirus holthuisi, the Red-striped Hermit Crab. Tropical West Atlantic. To one inch in length. One cheliped enlarged (usually right); movable pincer white. Eyestalks white with dark band, eyes grayish blue. 

 

Phimochirus opercularis, the Polka-Dot Hermit Crab.

 

Trizopagurus (Ciliopagurus) strigatus (Herbst 1804), the Striped or Halloween Hermit Crab. Indo-Pacific and Red Sea. To a little over two inches in length. Nocturnal. Lives in empty Cone shells. Feed on live and dead animal material.


Other Species of Hermits Sometimes Offered in the Interest that are Unusual, though not highly suitable for Aquarium use.

Manucomplanus varians (Benedict, 1892), Staghorn Hermit. Pix by Sara Mavinkurve.
http://www.liveaquaria.com/product/prod_display.cfm?c=497+501+1146&pcatid=1146

Other Species of Hermits Sometimes Offered in the Interest that are TROUBLE: For (large) fish-only systems.

Aniculus hopperae McLaughlin & Hoover 1996, Hopper's Hermit Crab. Sometimes imported from Hawai'i. Not a hardy aquarium species; apparently a sponge feeder in the wild. To an inch in length. Black eyes, yellow eye stalks, bright red claws bear black tips. Hawaiian endemic. Big Island pic. 

Aniculus maximus, a Large Hermit Crab. Often imported from Hawai'i. To four inches in length. 

 

Dardanus gemmatus H. Milne-Edwards 1848, Jeweled Anemone Hermit Crab. To two inches carapace length. With Calliactis anemones on its shell. Hawai'i image.

Dardanus lagopodes (Forsskal 1775), the Blade-eyed Hermit Crab. Indo-Pacific, including the Red Sea. To a little over two inches in length. White eye stalks, body mottled in maroon, brown, covered with white-tipped bristles. This one in Aitutaki, Cook Islands and N. Sulawesi.

Bigger PIX: The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

Dardanus megistos (Herbst 1789), Shell-Breaking Reef Hermit Crab, often sold as the White Spotted. Members of this genus are predaceous, and will gladly consume any fishes they can get their claws on. To six inches. Place with large, aware fishes only. Aquarium and N. Sulawesi pix.

Bigger PIX: The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.
Dardanus pedunculatus (Herbst 1804), another Reef Hermit Crab. Indo-Pacific. Often with anemones placed on its movable home/shell. To a little over two inches in length. Spiny chelipeds, red and white striped eye stalks are definitive. Aquarium and N. Sulawesi pix. 

Dardanus tinctor, a Coral Hermit Crab. This one with its Calliactis polypus Anemones out at night in the Red Sea. To 10 cm. Large left claw. Nocturnal; omnivorous. Moves anemones when transferring to new shells. 

Dardanus venosus, the Starry-eyed Hermit Crab. 3-5 inches. Blue/green eyes, dark pupils that are star-burst like in close view. Claws of lavender color generally. Bristly. Cozumel pic. 

Paguristes puncticeps, White Speckled Hermit Crab. Cozumel 2011.

Petrochirus diogenes, a Giant Hermit Crab. To twelve inches (not a mis-print). Caribbean.

 

The Superfamily Paguroidea also includes Stone Crabs like Lithodes, Paralithodes (commercial King Crab of the North Pacific).

Lithodes 

SIO Aquarium image. 

Care Notes:

If you use them, place about one, two small Hermits per actual gallon of your system. Use a mix of species and make sure and provide many "upgrade" homes (empty shells) for your Hermits to move to. 

Bibliography/Further Reading:

New Print and eBook on Amazon

Marine Aquarium Algae Control

by Robert (Bob) Fenner

Systematics of Crustacea: http://www.dnr.state.sc.us/marine/sertc/Martin%20&%20Davis.pdf

http://www.marbef.org/data/ermstaxdetails.php?id=106685

http://animaldiversity.ummz.umich.edu/site/accounts/classification/Anomura.html#Anomura

Baensch, Hans & Helmut Debelius. 1994. Marine Atlas, v.1. MERGUS, Germany. 1215pp.

Brawer, Marc. 1970. Hermit Crabs. Marine Aquarist 1:6, 70.

Burgess, Warren E. 1974. Salts from the seven seas (on Hermits). TFH 11/74.

Debelius, Helmut. 1999. Crustacea of the World. Atlantic, Indian, Pacific Oceans. IKAN, Germany 321pp.

Friese, U. Erich. Crustaceans in the home aquarium. Hermit Crabs. TFH 4/85.

Hoover, John P. 1997. Hawaiian Hermit Crabs, pts. I,II. FAMA 9,10/97.

Jensen, Christopher. 1998. Red Legged Hermit Crab. FAMA 4/98.

Menten, Bob. 1980. The Hermit Crab. Marine scavenger- par excellence. TFH 11/80

Michael, Scott. 1998. Hermit danger. Some species of hermit crabs actually consider your fish their dinner. AFM 5/98.


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