CLASS REMIPEDIA (1 ORDER)

• At present, this class is made of 12 cave-dwelling species with an interesting mix of primitive and advanced characters. Body composed of a head covered by a cephalic shield and a very long, 32-segment trunk, each segment with a pair of biramous legs. The body is not covered by a carapace (text with tooltip) A carapace is the exoskeletal plate that extends from the head posteriorly to cover much or all of the rest of the body in crustaceans. It also is the bony shell formed of fused ribs in turtles. . Last segment partly fused and with a telson. Mouth with unusual poison-injecting fang.
  • Cryptocorynectes, Godzillus, Lasionectes, Pleomothra, Speleonectes.

CLASS CEPHALOCARDIA (1 ORDER)

• Head covered by a cephalic shield to form a horseshoe-shaped head, 8-segmented thorax; 11-segmented abdomen with telson. Antennule uniramous (text with tooltip) Uniramous (adj.) means single-branched or unbranched. It usually refers to the unbranched leg of insects and other arthropods. ; 1st 7 thoracic limbs triramous (text with tooltip) Triramous (adj.) means three-branched. , with large, flattened pseudepipodite; abdomen without appendages except caudal furca with long bristles. They have no carapace or eyes. Hermaphroditic (text with tooltip) An animal that bears both male and female gonads. , with separate paired testes (text with tooltip) Testes (testis, sing.) is the male animal gonad. It produces sperm. and ovaries discharging through common ducts; benthic, marine.
  • Hampsonellus, Hutchinsoniella, Lightiella, Sandersiella.

CLASS MALACOSTRACA

• Small to very large; often with heavily calcified exoskeleton; 5 cephalic, 8 thoracic, and 6 (sometimes 7) abdominal segments; usually with stalked, compound eyes; carapace covering thorax (part or all) but never covering more than 1st or 2nd abdominal segments; first 1-3 pairs of thoracic appendages forming maxillipeds, 5 or more posterior pairs forming walking or swimming legs (pereiopods), 1+ pairs often chelate; abdomen with appendages (pleopods) modified for swimming and reproduction (sometimes for respiration), last pair ( uropods (text with tooltip) Uropods are flatted lateral appendages on the next to last segment of crustaceans that are used for swimming. ) broad, forming tail fan with telson; fertilized eggs often brooded.

• SUBCLASS PHYLLOCARDIA (1 ORDER)
• The only malacostracan group with 7 abdominal segments; all thoracic appendages phyllopodous; carapace covers thorax and laterally compressed; head with moveable rostrum; antennules biramous and antennae uniramous.
  • Dahlella, Levinebalia, Nebalia, Nebaliella, Nebaliopsis, Paranebalia.

• SUBCLASS EUMALACOSTRACA (13 ORDERS IN 4 SUPERORDERS)
• Body segments – 5 head, 8 thoracic, and 6 abdominal; 0-3 thoracic segments fused with the head; antennules and antennae bi- or uniramous; antennae often with exopod; carapace well-developed; thoracic epipods function as gills; abdomen usually long and muscular.
  • Anaspides, Paranaspides, Koonunga, Bathynella, Thermobathynella
  • Thermosbaena, Monodella, Spelaeogriphus, Mysis, Neomysis, Gnathophausia, Cumopsis, Leptocuma, Diastylis, Cyclaspis, Aspeudes, Sphyrapus, Tanais, Heterotanais, Oniscus, Porcellio, Armadillidium, Ligyda, Asellus, Idotea, Arcturus, Gnathia, Cymnothoa, Bathynomus, Ione, Liriopsis, Phreatoicus, Gammarus, Hyallela, Orchestia, Caliopius, Siphonectes, Hyperia, Caprella, Ingolfiella.
  • Euphausia, Meganyctiphanes, Nyctiphanes, Lucifer,Penaeus, Crangon, Heterocarpus, Stenopus, Callianidea, Callianassa, Polyonyx, Callinectes, Uca, Neopanopeus, Cambarus, Cambarellus, Homarus, Clibanarius, Emerita, Sesarma.
  • Squilla, Echinosquilla, Gonodactylus, Hemisquilla, Lysiosquilla, Pseudosquilla, Coronida, Odontodactylus.

CLASS MAXILLOPODA

• Small to very large; often with heavily calcified exoskeleton; 5 cephalic, 8 thoracic, and 6 (sometimes 7) abdominal segments; usually with stalked, compound eyes; carapace covering thorax (part or all) but never covering more than 1st or 2nd abdominal segments; first 1-3 pairs of thoracic appendages forming maxillipeds, 5 or more posterior pairs forming walking or swimming legs (pereiopods), 1+ pairs often chelate; abdomen with appendages (pleopods) modified for swimming and reproduction (sometimes for respiration), last pair (uropods) broad, forming tail fan with telson; fertilized eggs often brooded.

• SUBCLASS PHYLLOCARDIA (1 ORDER)
• The only malacostracan group with 7 abdominal segments; all thoracic appendages phyllopodous; carapace covers thorax and laterally compressed; head with moveable rostrum; antennules biramous and antennae uniramous.
  • Dahlella, Levinebalia, Nebalia, Nebaliella, Nebaliopsis, Paranebalia.

• SUBCLASS EUMALACOSTRACA (13 ORDERS IN 4 SUPERORDERS)
• Body segments – 5 head, 8 thoracic, and 6 abdominal; 0-3 thoracic segments fused with the head; antennules and antennae bi- or uniramous; antennae often with exopod; carapace well-developed; thoracic epipods function as gills; abdomen usually long and muscular.
  • Anaspides, Paranaspides, Koonunga, Bathynella, Thermobathynella
  • Thermosbaena, Monodella, Spelaeogriphus, Mysis, Neomysis, Gnathophausia, Cumopsis, Leptocuma, Diastylis, Cyclaspis, Aspeudes, Sphyrapus, Tanais, Heterotanais, Oniscus, Porcellio, Armadillidium, Ligyda, Asellus, Idotea, Arcturus, Gnathia, Cymnothoa, Bathynomus, Ione, Liriopsis, Phreatoicus, Gammarus, Hyallela, Orchestia, Caliopius, Siphonectes, Hyperia, Caprella, Ingolfiella.
  • Euphausia, Meganyctiphanes, Nyctiphanes, Lucifer,Penaeus, Crangon, Heterocarpus, Stenopus, Callianidea, Callianassa, Polyonyx, Callinectes, Uca, Neopanopeus, Cambarus, Cambarellus, Homarus, Clibanarius, Emerita, Sesarma.
  • Squilla, Echinosquilla, Gonodactylus, Hemisquilla, Lysiosquilla, Pseudosquilla, Coronida, Odontodactylus.

CLASS MAXILLOPODA

• Segments- 5 head, 6 thoracic, 4 abdominal (sometimes the body plan is reduced); thoracic appendages usually without epipods; abdomen reduced and lacking “full compliment of legs”. In general, they appear to be neotenic, that is larval in form as sexually mature adults which accounts for their variability in form. There still is some disagreement as to the monophyly of this group. Some systems exclude the Ostracods.

• SUBCLASS THECOCOSTRACA (CIRRIPEDIA) (4 ORDERS)
• Free-living or parasitic; adults sessile; parasitic forms highly modified. Free-living forms attached to substratum by cement from antennules; carapace covering body and limbs, often with discrete calcareous plates; reduced abdomen and segmentation; 6 pairs of biramous thoracic limbs ( cirri (text with tooltip) Cirri (cirrus, sing.) are tendril-like structures. They occur on the terminal segments of some insects and crustaceans. They are the feeding structures of barnacles, respiratory and copulatory structures in annelids. Cirri also serve as copulatory structures in some mollusks and flatworms. ) used to comb or filter water; adults without antennae or compound eyes; mostly hermaphroditic with cross-fertilization by elongate penis. Marine.
  • Conchoderma, Lepas, Balanus, Mitella, Tripetesa, Baccalaureus, Dendrogaster, Ascothorax, Laura, Sacculina, Synagoga, Zoanthoecus, Briarsaccus, Loxothylacus, Hansenocaris, Cryptophialis, Typetesa, Heterosaccus, Lernaeodiscus, Mycetomorpha, Peltogaster, Sylon, Chthamalus, Coronula, Pollicipes, Tetraclita, Verruca,

• SUBCLASS TANTULOCARDIA (1 ORDER)
• Parasites of other crustaceans; free-swimming larval forms with flattened cephalic, shield thorax of 6 segments, and abdomen of up to 7 segments; abdomen without appendages; adults reduced to a sac, reduced abdomen and sex organs.
  • Basipodella, Doeterthron, Microdajus.

• SUBCLASS BRANCHIURA (1 ORDER)
  • Flattened ectoparasites of fish; carapace covers head and most of body; with 3 free thoracic segments, paired moveable compound eyes, median ocellus, bilobed unsegmented abdomen; 1st maxillae form suckers; antennules with large terminal hook. Attachment to host periodic, biramous thoracic limbs used for locomotion.
  • Argulus, Chonopeltis, Dipteropeltis, Dolops.

• SUBCLASS MYSTACOCARDIA (1 ORDER)
• Minute, elongate; head divided into 2 regions; without compound eyes, with 2 pairs of ocelli; 4 pairs of simple, singly-segmented appendages on thoracic segments 2-5; antennules, antennae and maxillae large; appendages of 1st thoracic segment form maxillipeds; abdomen 5-segmented plus telson with large, claw-like furca; pairs of dentate furrows laterally on posterior head, thorax and abdomen; benthic, marine.
  • Ctenocheilocaris, Derocheilocaris.

• SUBCLASS COPEPODA (10 ORDERS IN 2 INFRACLASSES)
• Usually small; short body composed of a head fused to 1+ thoracic segments and 8 free segments plus telson (with further fusion in some); with carapace or paired eyes; with well-developed nauplius eye; uniramous antennules, appendages of 1st thoracic segment forming maxillipeds, and 4-5 other pairs of thoracic appendages; body often with rounded anterior margin, oval head + thorax, narrow abdomen ending in caudal furca; commensal, free-living and parasitic, parasitic species highly modified.
  • Antrisocopia, Platycopia.
  • Calanus, Diaptomus, Eucalanus, Euchaeta, Metridia, Calocalanus, Cyclops, Eucyclops, Lernaea, Mesocyclops, Metacyclops, Notodelphis, Gelyella, Harpacticus, Elaphoidella, Epactophanes, Longipedia, Monstrilla, Peltidium, Porcellidium, Psammus, Sunaristes, Tisbe, Boxshallia, Misophrya, Monstrilla, Stilloma, Mormonilla, Chondracanthus, Erebonaster, Ergasillus, Pseudanthessius, Clavella, Nemesis, Pontoeciella, Trebius, Acidicola, Notodelphys, Doropygus, Penella, Lepeophtherius, Samnicola, Branchiella.

• SUBCLASS OSTRACODA (5 ORDERS IN 2 SUPERORDERS)
• Small, enclosed in a bivalved carapace; body unsegmented externally, with 5-7 pairs of thoracic limbs; carapace shed and reconstituted at each molt.
  • Cypridina, Euphyllomedes, Eusarsiella, Pyrocypris, Gigantocypris, Skogsbergia, Vargula, Conchoecia, Polycope.
  • Cypris, Candona, Celtia, Darwinula, Limnocythre, Cytherella, Sclerocypris, Manawa, Bairdia, Bythocypris.

• SUBCLASS PENTASTOMIDA
• The name literally means five mouths, which is a reference to the five libes at the anterior end of the animal. The pentastomes are parasites of vertebrate carnivores and usually have an intermediate host for their larvae and three larval stages. The first larval stage develops in the egg after it is ingested by the intermediate host. That is followed by the second stage, which resembles a tardigrade and burrows through the gut of the host where it seeks out organs like the liver, encapsulates and forms the third larval stage. The adult develops when the encapsulated larva is eaten by a host animal. As adults, they seem to prefer the lungs of vertebrates.
• They appear to be highly modified members of the panarthropoda. Indeed, Margulis and Schwartz (1998) and Brusca and Brusca (2003) place them together with the crustaceans. Nielsen (2001) is more careful and suggests a “proarthropod” position mainly because they are so modified and synapomorphies are so difficult to identify.
  • Pentastomum, Reighardia, Cephalobaena, Porocephalus, Armillifer, Linguatula, Waddycephalus.