Minnesota Crustaceans

 
Subphylum Crustacea

Crustacea is the subphylum of animals that is characterized by the following:

  • Crustaceans have a hard external skeleton (exoskeleton).
  • Most crustaceans are aquatic.
  • The head has five appendages: two pairs of antennae, a pair of mandibles (jaws for holding and tearing food), and two pairs of maxillae (for transferring food to the mandibles).
  • The head and thorax are fused together (cephalothorax), which is usually covered by a single continuous shield (carapace).
  • Early development of most crustaceans includes a stage in which only a few limbs are present (nauplius larval stage). In this stage there is a unique structure with which the larva chews its food (naupliar arthrite), and a single, simple, median eye (naupliar eye).
  • Most crustaceans have appendages or limbs on the thorax and abdomen that split into two branches (biramous).
  • Crustaceans carry their eggs until they hatch, then release larvae into the water.

 

The study of crustaceans is called carcinology. There are almost 68,000 described crustacean species worldwide. About 15% of these are inland water species, the remainder are marine species. In North America, about 1,500 freshwater species have been described.

In the United States, 22 crustacean species are protected under the Endangered Species Act. In Minnesota, two are considered invasive.


virile crayfish

Photo by Kirk Nelson

 

 

           

Recent Additions

 
Rusty crayfish
   

Rusty crayfish (Orconectes rusticus) is a medium- to large-sized freshwater crustacean. It is native to Michigan, Ohio, and Kentucky. It is used extensively by fishermen as bait, and is sold as an aquarium pet. Unused bait and release of aquarium pets have resulted in the introduction of this species across the United States. It is considered invasive outside of its native range.

Rusty crayfish are extremely aggressive. They out-compete and eventually eliminating native crayfish species when introduced into a new site. Juveniles have a higher metabolic rate, eat twice as much, and develop much faster than native crayfish species of similar size.

Rusty crayfish is identified by a rust-colored spot on each side of its upper shell; a rust-colored stripe on the uppers side of its abdomen; and very large claws with an S-shaped movable finger.

  rusty crayfish
  Photo by LMG
   
   
   
   
   

Virile crayfish
   

Virile crayfish (Orconectes virilis) is a medium- to large-sized freshwater crustacean. It is widespread and abundant across North America. It is native to central United States and Canada, from Quebec to Tennessee in the east, to Alberta and Colorado in the west. It is introduced and considered invasive outside of its native range from coast to coast.

Virile crayfish prefer streams with rocky bottoms, moderate flow and turbidity, abundant cover, and stable water levels. They often use rocks, logs, or other organic debris as cover. They occasionally dig burrows into muddy banks, especially when water levels are low. To survive the winter, they migrate to deeper water that does not completely freeze and they become inactive.

Virile crayfish are identified by the dappled, olive-brown body with pairs of dark brown splotches on the abdomen; the shape of the shield (carapace) covering the front part of the body; and the broadly flattened, usually bluish claws.

  virile crayfish
  Photo by Kirk Nelson
   
   
   
   
   
   
   

Other Recent Additions
   

 

 

 

 

 

 

 

 

 

           
Profile Photo Video      

     

burrowing amphipod (Diporeia sp.)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

rusty crayfish

virile crayfish

     

calico crayfish (Orconectes immunis)

 
     

Couse tadpole shrimp (Lepidurus couesii)

 
     

devil crayfish (Cambarus diogenes)

 
     

eastern alkali fairy shrimp (Branchinecta readingi)

 
     

eastern fairy shrimp (Eubranchipus holmanii)

 
     

Ellis Bog crangonyctid (Crangonyx richmondensis)

 
     

freshwater shrimp (Gammarus fasciatus)

 
     

golden crayfish (Orconectes luteus)

 
     

holarctic clam shrimp (Lynceus brachyurus)

 
     

knobbedlip fairy shrimp (Eubranchipus bundyi)

 
     

northern clearwater crayfish (Orconectes propinquus)

 
     

northern river crangonyctid (Crangonyx pseudogracilis)

 
     

northern spring amphipod (Gammarus pseudolimnaeus)

 
     

ornate fairy shrimp (Eubranchipus ornatus)

 
     

red swamp crayfish (Procambarus clarkii)

 
Profile Photo Photo

rusty crayfish (Orconectes rusticus)

 
     

scud (Hyalella azteca)

 
     

smoothlip fairy shrimp (Eubranchipus intricatus)

 
     

spinytail fairy shrimp (Streptocephalus sealii)

 
Profile Photo Photo

virile crayfish (Orconectes virilis)

 
     

White River crawfish (Procambarus acutus)

 
     

 

 

 

No Species Page Yet?

If you do not see a linked page for an amphibian in the list at left you can still upload a photo or video as an email attachment or report a sighting for that amphibian. Click on one of the buttons below and type in the common name and/or scientific name of the amphibian in your photo, video, or sighting. A new page will be created for that amphibian featuring your contribution.

 

 

 

 

 

 

 

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