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TAXONOMY of COMMON HERMIT CRABS of INDIA Bijukumar, A

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Advances in Finfish and Shellfish Taxonomy, Pages: 11–68 Edited by: A.K. Jaiswar et al. Copyright © 2018, Narendra Publishing House, Delhi, India 14 TAXONOMY OF COMMON HERMIT CRABS OF INDIA Bijukumar, A. 1 and Reshmi, R. 2 Department of Aquatic Biology & Fisheries, University of Kerala, Thiruvananthapuram 695581, Kerala, India Email: 1bi [email protected]; 2r [email protected] Introduction Infraorder Anomura, commonly referred to as anomurans or false crabs in scientific literature, is one of the most diverse groups of crustaceans in the phylum Arthropoda. Infraorders Brachyura and Anomura comprise the entire crab community of the order Decapoda. Infraorder Anomura is represented by 6 superfamilies, 17 families, 223 genera and around 2500 species. The taxonomic status of several species is unclear and discovery of new species is increasing day by day. Infraorder Anomura Macleay, 1838 is represented by six superfamilies: Aegloidea, Hippoidea, Lithodoidea, Lomisoidea, Paguroidea and Galatheoidea. Superfamily Aegloidea Dana, 1852 is represented by a singlefamily Agelidae comprising 69 species in one genus. Superfamily Hippoidea Latreille, 1825 comprises three families of sand and mole crabs in Albuneidae (48 species in 9 genera), Blepharipodidae (6 species in 2 genera) and Hippidae (27 species in 3 genera). Superfamily Lithodoidea Samouelle, 1819 is with two families­ Hapalogastridae and Lithodidae (129 species in 15 genera). Superfamily Lomisoidea Bouvier, 1895 is represented by a single family Lomisidae compising a single species Lomis hirta (hairy stone crab). Superfamily Paguroidea Latreille, 1802 comprises hermit crabs and their relatives in the families Coenobitidae (17 species in 2 genera), Diogenidae (428 species in 20 genera), Paguridae (542 species in 75 genera), Parapaguridae (76 species in 10 genera)(Lemaitre, 1996; McLaughlin, 2003), Pylochelidae (52 species in 10 genera) and Pylojacquesidae (2 species in 2 genera). Superfamily Galatheoidea Samouelle, 1819 includes squat lobsters and related animals in four families such as Galatheidae (675 species in 34 genera), Chirostylidae (192 species in 7 genera), Kiwaidae with only one species Kiwa hirsuta (‘yeti lobster’) and Porcellanidae (225 species). 132 Advances in Finfish and Shellfish Taxonomy Among anomurans hermit crabs of the super family Paguroidea Latreille, 1802 represent an important portion of the intertidal, sublittoral and moderately deep benthic marine communities worldwide, with high diversity in tropical and subtropical regions, where they play an important role in food web. Hermit crabs are ecologically important scavengers, feeding on organic deposits and also good predators. They are typically marines organisms seen in intertidal as well as subtidal environments, although some species have physiological and behavioural adaptations for living in almost all habitats such as estuarine, semi­terrestrial and terrestrial habitats; they therefore, form important specimen for research. Hermit crabs can be considered as ecological indicators of freshwater inundation as they have the physiological adaptations to withstand the fluctuating conditions in the intertidal zone. They are decapod crustaceans with ten pereopods, but the last pair of these is often hidden under the gill chamber and is used for keeping the gills clean. They have a soft abdomen and for safety from predation, desiccation and mechanical damage they keep the abdomen tucked away in a discarded gastropod shell or cavities of appropriate size. Few hermit crabs are found inhabiting shelters other than shells, which includes bivalve and scaphopod shells, hollowed cylinders of wood or stone, calcareous tubes of polychaetes or vermetid gastropods which are immobile, corals, and sponges. Terrestrial hermit crab, popularly known as “coconut crab” [Birgus latro (Linnaeus, 1767)], is fully calcified and exist without a shell, although megalopa larvae and young crabs of this species require shells. Hermit crabs obtain new shells or housing by exchanging or sharing shells among individuals of same or different species, seeking empty shells or migrating to areas where gastropod shells are abundant. Hermit crabs seem to select among the available empty gastropod shells the most suitable one for their size and shape. The life cycle of hermit crabs depends on the process that makes suitable gastropod shells. Shells are considered as a limiting factor for hermit crab survival. The gastropod shells occupied by hermit crabs provide mobility and protection which had helped them to establish in marine and tropical terrestrial shores. Despite their ecological importance the studies on the distribution patterns in hermit crabs are scarce. Members of the family Coenobitidae are commonly called as “land hermit crabs”. They are semi­terrestrial hermit crabs represented by 17 species in two genera viz., Coenobita (16 species) and Birgus (one species). Hermit crabs of the family Diogenidae are commonly known as “left­ handed” hermit crabs as they have appreciably larger left cheliped than the right. They are seen in all habitats, mainly in tropical and temperate areas, in depths ranging from the intertidal to over 465 m. They are very rare in higher latitudes. Out of the six families Diogenidae is the most species­rich family. Taxonomy of Common Hermit Crabs of India 133 Members of the family Paguridae are commonly called as “right handed” hermit crabs because the members have right cheliped larger than the left. This family has the highest number of genera and species. They are commonly found in the intertidal areas of temperate zone in depths of 50­500 m. The Parapaguridae or “deep­water hermit crabs” are species typically found at depths ranging from 200 to 3000 m. There are five genera, Oncopagurus Lemaitre, 1996; Parapagurus Smith, 1879; Sympagurus Smith, 1883; Tylaspis Henderson, 1885 and Probeebei Boone, 1926, with species having reduced corneas, as they are mainly seen in the twilight zone (Lemaitre, 2006). Family Pylochelidae Bate, 1888 are known as “symmetrical” hermit crabs because they have symmetrical chelipeds, straight pleon, partially calcified articulated tergites, and generally symmetrical uropods. The habitats of pylochelids are pieces of wood, rocks, sponges, tusk shells, and rarely gastropods. They are found in depths ranging from 30 to 1570 m, most frequently occurring in depths from 200 to 500 m. Family Pylojacquesidae McLaughlin and Lemaitre, 2001 is unique among anomurans in having mandible which is chitinous and strongly toothed and they reflect an unusual neotenous or paedomorphic condition. Hermit crabs are fascinating specimens for zoologists because of their intelligent selection of suitable discarded shells as their ‘home’. Hermit crabs are also used as an ideal experimental organism to study environmental influences as they are seen many in the intertidal and deep marine benthic communities and their presence in these areas are due to adaptive evolution of the population, thus forming an important organism in the living world. Taxonomy Kingdom: Animalia Phylum: Arthropoda Subphylum: Crustacea Class: Malacostraca Order: Decapoda Suborder: Pleocyemata, Infraorder Anomura Crustaceans of the infraorder Anomura are characterized by having adult body shapes from lobster­like to true crab­like and highly reduced fifth pereopods which is used for keeping the gills clean. The abdomen may be elongated, short and folded under the body or tightly curved to fit into the gastropod shells. Markedly reduced fifth pereopods that are not used as ambulatory appendages, the articulated 134 Advances in Finfish and Shellfish Taxonomy or missing eighth thoracic sternite and the cephalothorax that is not fused to the epistome are the major characters of this infraorder. Body parts of hermit crabs and their taxonomic charactes are shown in Figs. 1 to 6. Common Families occurring in India Hermit crab diversity in India is represented by over 110 species and the families represented in India are Coenobitidae, Diogenidae, Paguridae, Parapaguridae and Pylochelidae. Key to the identification of common families of hermit crabs (super family Paguroidea) are given below: Keys to the families of Paguroidea 1. Antennules with upper rami of flagella terminating bluntly, ... Coenobitidae somewhat “stick­like” (semiterrestrial) — Antennules with upper rami of flagella terminating in ... 2 tapered filament, not “stick­like” (marine, estuarine) 2. Paired pleopods on abdominal somites 2–5; abdominal ... Pylochelidae tergites 1–5 well defined, well calcified — No paired pleopods on abdominal somites 4 and 5; ... 3 abdominal tergites variable, but most frequently not well calcified 3. Maxilliped 3 generally approximate basally;chelipeds equal, ... Diogenidae subequal or unequal, left frequently largest ….. — Maxilliped 3 generally widely separated basally; ... 4 chelipeds unequal or less frequently subequal, right usually largest 4. Exopod of maxilliped 1 with flagellum ... Paguridae — Exopod of maxilliped 1 without flagellum ... Parapaguridae I. FAMILY: COENOBITIDAE (Land hermit crabs) The Coenobitidae are the family of terrestrial hermit crabs, widely known for their terrestrial habits, with 17 species in two genera. The genus Birgus is represented by a single species, the well­known Birgus latro. Description: Carapace cylindrical or subcylindrical, well calcified ; elongate or broadened at posterior half. Rostrum obsolete or very prominent. Outer ocular spine absent, ocular acicles present.Cornea well developed. Antennal
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  • Hermit Crab Care

    Hermit Crab Care

    HERMIT CRAB BASIC CRAB CARE Just the Basics To live comfortably in captivity, hermit crabs require the following: no lower than 75°F. Consistent low temperatures can kill a hermit crab. Don't allow them to bake in a window, either. If they get too hot they will die, overheating causes irreversible damage and a slow, painful death. Signs of overheating are a musty smell and discharge of brown liquid; crabitat to have a moist, "tropical" feel to it; at it negates the effects of your under- tank heater. If you are having trouble keeping your crabitat warm, try moving some substrate from over the heater. If you are having trouble getting the crabitat to cool down, turn off the heater. See the molting page if you need information on heating a molter's isolation tank; Food, water, shells and other tank decorations to keep the crabs engaged and active. Friends I'm sure you've heard this before, but you really shouldn't keep only one hermit crab alone as a pet. The name 'hermit' is misapplied to our little friends -- they are quite gregarious and like to be around their own kind. In the wild, they travel in packs of up to 100 crabs, scavenging the beach for food and shells. The reason they travel in packs is simple: Where there are more crabs, there are more shells. Researchers have found by putting one clean, empty shell on the beach, they can initiate a "cascade" of shells changes: One crab changes in to the new shell, another changes into his old shell, and another changes into the other empty shell, and so on.
  • Crustacea, Decapoda, Anomura, Paguroidea) with Subconical Corneas, and New Data on Biology of Some Rare Species

    Crustacea, Decapoda, Anomura, Paguroidea) with Subconical Corneas, and New Data on Biology of Some Rare Species

    Two new species of Parapaguridae (Crustacea, Decapoda, Anomura, Paguroidea) with subconical corneas, and new data on biology of some rare species Rafael LEMAITRE Smithsonian Institution, National Museum of Natural History, MRC 163, Deparment of Invertebrate Zoology, P.O. box 37012, Washington, D.C., 20013-7012 (USA) [email protected] Lemaitre R. 2006. — Two new species of Parapaguridae (Crustacea, Decapoda, Anomura, PaguroKlea) with subconical corneas, and new data on biology of some rare species. Zoosvs- tema28(2):517-532. ABSTRACT Two new parapagurid species with subconical corneas, Oncopagurus conicus n. sp. and Paragiopagurus schnauztr n. ap., are described based on collections by French expeditions to New Caledonia, the Philippines and Solomon Islands, in the we-stern Pacific. These represent the 16th and 18th documented species of Oncopagurus Vemixtyc, 1996 and Paragiopagurus\jimw.K, 1996, respectively. KEYWORDS Two other parapagurids arc known to have subconical corneas, Sympagurus Crustacea, acinops Lemaitre, 1989, and Oncopagurus minutus (Henderson, 1896). Also Decapoda, Anotnura, rejxirtcd are specimens of two rare and morphologically unique parapagurids, Parapaguridae, lyphlopagurtis foresti de Saint Laurent, 1972 and Bivalvopagurus sinensis (de ParagiopaguruSy Saint I aurent, 1972), and represent geographical and bathymetric range c-xten- Oncopagurus, Typhlopagurtis, sions for both species. The diagnoses of the monotypic genera Typhlopagurus Bivalvopagunis, and Bivalvopagurus are to be modified due lo new data on morphology and hermit crabs, biology. The former genus was given to inclutle T foresti, wrongly assumed to deep-water, misnomers, lack a>rnea, thus presumed blind; and the latter for B. sinensis, prematurely new species. assumed to exclusively use bivalve shells as housing. ZOOSYSTEMA • 2006 • 28 (2) O Publications ScientHiquas du Musium national d'Histoire natureNe, Paris.