Everything You'll Need to Know About A Rusty Crayfish's Life



http://www.seagrant.umn.edu/ais/rustycrayfish_invader

    

     Rusty crayfish live in lakes, streams, and ponds.  They prefer areas that offer rocks, logs, or other debris as cover. Bottom types may be clay, silt, sand, gravel, or rock.  Rusty crayfish inhabit both pools and fast water areas of streams. They generally do not dig burrows other than small pockets under rocks and debris, although there have been reports of more substantial burrows.  Rusty crayfish need permanent lakes or streams that provide suitable water quality year-round.

    

A female rusty crayfish with eggs.

     Mature rusty crayfish mate in late summer, early fall, or early spring.  The male transfers sperm to the female.  She stores the sperm until her eggs are ready to fertilize, typically in the spring as the water temperature begins to increase.  Stored sperm are released as eggs are expelled and external fertilization occurs. The eggs are then attached to the swimmerets on the underside of the crayfish's abdomen ("tail section").  Rusty crayfish females can lay from 80 to 575 eggs.
     Eggs hatch in three to six weeks, depending on water temperature.  Once hatched, young crayfish cling to the female's swimmerets for three to four molts.  Young crayfish may stay with the female for several weeks. She offers them protection during this vulnerable life stage. Eventually, the young leave the female. They undergo eight to ten molts before they mature, which may occur during the first year, but more likely in the following year. Rusty crayfish reach maturity at a total length of one and three-eighths inches (3.5 cm) and reach a maximum length of about four inches (10 cm), not including claws.
     Growth slows considerably after crayfish attain maturity.  Males typically molt twice a year while females only molt once a year.   Females molt after the release of their young, typically in June or early July.   Because males have an additional molt each year, they are usually larger than females of the same age.  A typical rusty crayfish lives three to four years.
    Crayfish are considered opportunistic feeders. Rusty crayfish feed on a variety of aquatic plants, benthic invertebrates (like aquatic worms, snails, leeches, clams, aquatic insects, and crustaceans such as side-swimmers and waterfleas), detritus (decaying plants and animals, including associated bacteria and fungi), fish eggs, and small fish. Juveniles especially feed on benthic invertebrates like mayflies, stoneflies, midges, and side-swimmers.