These arthropods all have a hard exoskeleton and at least 10 legs.
Crustaceans have jointed legs. Many (including crabs, lobsters, crayfish, and shrimp) are aquatic and have 10 appendages including their claws, but the woodlice live on land and have 14 legs.
List of all crustaceans recorded in Columbia County
Common Pill Woodlouse – The only woodlouse species that rolls into a ball with no gaps. Feeds on decaying plant matter and lichen. Originally from Europe, introduced to the USA. (photo © Jessica Hird)
Common Woodlouse – Also known as “Common Shiny Woodlouse”, it feeds on dead plants, animals, and wood. Introduced to the USA from Europe. (photo © Jessica Hird)
Rough Woodlouse – Often found in communities with other woodlice species. Feeds on decaying plant matter. An introduced species from Europe. (photo © Jessica Hird)
Common Striped Woodlouse – Known as “Fast Woodlouse” as it runs away when exposed rather than hunkering down like the other species. Introduced from Europe. (photo © Jessica Hird)
Signal Crayfish – Our native “crawdad”, can be identified by smooth claws with white bump at joint and a single body plate. (photo © Karen & Mike)
Red Swamp Crayfish – Bumps on claws and a split body plate. Introduced from Louisiana, can wreck native crayfish, fish and amphibian populations. (photo © dickwood)
Millipedes and centipedes form a group called Myriapods, which means “many-legged”. Different species have anywhere from several dozen to several hundred legs. Millipedes eat decaying plant matter while centipedes are predators that hunt down insects and other small creatures.
List of all myriapods recorded in Columbia County
Yellow-spotted Millipede – Found in moist forest where it composts leaf litter. Emits hydrogen cyanide as a defense mechanism. (photo © Melissa McMasters)
Black Round Millipede ( – A large millipede up to 4″ long, it is native to the moist regions west of the Cascades. (photo © Tylobolus uncigerus) Tomas Quinones)
Greenhouse Millipede – Originally native to Japan, it is now found in suitable habitats across the world, usually in greenhouses and gardens. (photo © giorege1959)
Pacific Flat-backed Millipede ( ) – A Flat-backed Millipede found only in the coastal ranges of the Pacific Northwest. (photo © Nearctodesmus insulanus William Leonard)
Brown Centipede – Native to Europe but now found worldwide, this short (~1″) brown centipede is found in yards and gardens. It has 30 legs. (photo © Ryzhkov Oleg)
Thorn-tailed Bark Centipede ( – These 2-3″ Bark Centipedes are found under the bark of dead trees in moist coastal forest. They have 46 legs. (photo © Scolopocryptops spinicaudus) James Bailey)
Crimson Soil Centipede ( – A very long but very slender local centipede, it can have over 150 legs. They are found under rocks or logs of the forest soil. (photo © Strigamia epileptica) W. Mason)
House Centipede – Originally from Mediterranean but now in and near homes everywhere, this long-legged centipede can cover 15″ a second. (photo © Keir Morse)
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