Crustacea (amphipods, isopods, decapods)

The Subphylum or Class Crustacea includes many important Orders 

that inhabit caves and other habitats. Crustaceans have biramous (two-

branched) appendages, gills, and other characteristic structures. A few

are terrestrial, such as pillbugs (a type of isopod) and land crabs. Most

of the species below are aquatic. Cave crustaceans may have inhabited

our groundwater since before our current caves existed.

8/01

 

035.jpg: Crangonyx forbesi Hubricht and Mackin, SP: A common stygophile, about 17 mm, this eyed and pigmented amphipod is known from a wide variety of microhabitats, including riffles and pools of streams, rimstone pools and drip pools in all cave zones, and from surface springs. This aggregation, from Lone Hill Onyx Cave, Franklin County, apparently exhibits reproductive behavior. Widespread in the Midwest.
035.jpg		 036a.JPG: Stygobromus ozarkensis (Holsinger), SB: A blind amphipod, about 13 mm, found in the Springfield Plateau of southwestern Missouri and adjacent parts of Arkansas and Oklahoma. Photo from Tumbling Creek Cave, Taney County. Perhaps 12 species of Stygobromus are known from Missouri caves, springs, and wells. About 200 species, all subterranean, occur in the Northern Hemisphere.
036a.JPG		 036b.GIF: Distribution map of Stygobromus amphipods in Missouri and adjacent states. Some species are very localized in a few caves while others range over large areas in groundwater .
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037.JPG: Bactrurus brachycaudus Hubricht and Mackin, PB: At 19-30 mm long, the largest freshwater amphipod in North America occurs in caves, springs and wells in Missouri and Illinois. Three species of Bactrurus occur in subterranean Missouri.
037.JPG		 038.JPG: Allocrangonyx hubrichti Holsinger, SB: Male, 15 mm long, a rare "species of concern" in Missouri. Elliott has given this amphipod a new common name, "Hubricht's long-tailed amphipod," referring to the long third uropods in the male. Formerly called the "Central Missouri cave amphipod," this species was reported from a well in Arkansas in 2000. By James E. Gardner.
038.JPG		 039.JPG: Caecidotea sp., SB: An aquatic isopod, about 20 mm long. Missouri caves have at least 11 species of Caecidotea, a widely distributed subterranean genus in North America.
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040.JPG: Lirceus sp., SP or SX: An aquatic isopod about 10 mm long from Hercules Lookout Cave, Taney County, Missouri. This eyed species has been collected from riffles and pools of streams, isolated pools with muddy bottoms and deep rimstone pools, in all zones. Although Hubricht and Mackin (1949) reported five species of Lirceus from Missouri, the scientific consensus is that these descriptions were inadequate to distinguish the species. By James E. Gardner.
040.JPG		 041.JPG: Trichoniscid isopods like this Brackenridgia from Texas (about 5 mm) have been found in Missouri. An undescribed, troglobitic Caucasonethes has been found in Carter and Taney counties, and troglophilic Miktoniscus sp. are known from Crawford and Howell counties. They are found in rotting wood and soil. Some trichoniscids are amphibious.
041.JPG		 042.JPG: Armadillidium vulgare (Latreille), TX: Pillbug isopods, 5-10 mm long, rolling up, by James E. Gardner. This introduced species is in several states. It occurs in the loose soil, leaves, sticks and excrement of turkey vulture nests and far from cave entrances in total darkness. Softer, pale
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043.JPG: Bristly Cave crayfish, Cambarus setosus Faxon, SB: Adults 53-119 mm long. Known from about 44 caves, springs, and wells in a nine-county area on the Springfield Plateau, and a few sites in northeastern Oklahoma. This species has small, unpigmented eyes, and it can respond to light. The setae on the pincers are long and bristly. A "species of concern" in Missouri. By Rick Thom.
043.JPG		 044a.jpg: Salem Cave crayfish, Cambarus hubrichti Hobbs, SB: Adults 58-94 mm long. Superficially it looks like the Bristly cave crayfish, but it has short, inconspicuous setae on the pincers; other smaller characteristics differ. This species occurs in the east-central Ozarks of Missouri, from about 21 caves and springs from Camden and Crawford counties south to Howell and Ripley. It has small, unpigmented eyes, and it responds quickly to light and vibrations. A "species of concern" in Missouri. By James E. Gardner.
044a.jpg		 044b.jpg: A tank full of Cambarus hubrichti Hobbs, Salem cave crayfish, rescued from a kill in Meramec Spring caused by an ammonia pipeline spill into the Meramec Spring system, Crawford County , Missouri, 1981. By Tom Johnson, MDC.
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044c.jpg: Cambarus hubrichti Hobbs, Salem cave crayfish, ovigerous (egg-carrying) female, Meramec Spring, Crawford County, Missouri. This specimen was rescued from a kill in the spring caused by an ammonia pipeline spill. By Tom Johnson, MDC, 1981.
044c.jpg		 045a.jpg: Caney Mountain cave crayfish, Orconectes new species, being desribed by H.H. Hobbs, III. SB: Adults 84-104 mm. This species, discovered in 1999, is known only from one cave in the Caney Mountain Natural Area, Ozark County. The small, vulnerable population is protected and periodically checked by MDC biologists. It is closely related to O. pellucidus, the Mammoth Cave crayfish, and is the first stygobitic Orconectes found west of the Mississippi River.
045a.jpg		 045b.jpg: A new species of cave crayfish from Caney Mountain Conservation and Natural Area, Ozark County, Missouri. Note the male gonopods, mating organs which are stiffened swimmerets lying between the last pair of walking legs.
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045c.jpg: Orconectes pellucidus, Mammoth Cave, Kentucky, by Chip Clark. This species is the closest living relative to the new cave Orconectes from Missouri. Probably an ancient ancestor, now extinct, ranged over the midwestern United States and colonized spring caves.
045c.jpg		 046.jpg: Spothanded crayfish, Orconectes punctimanus (Creaser), TX: Adults 32-110 mm long. A pair of crayfish mating in a cave stream. This eyed species likes to wander upstream into caves.
046.jpg		 047.jpg: Male gonopods of Missouri cave crayfishes: a) Ventral view of gonopods between posterior walking legs, Orconectes stygocaneyi. b) Form 1 (mature), O. stygocaneyi, right gonopod, ventral view. c) Form 1, Cambarus hubrichti. d) Form 1, Cambarus setosus. e) Form II (immature) gonopod, C. setosus. Form II usually cannot be identified to species. Drawings by William L. Pflieger and Horton H. Hobbs, III.
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