TN00510 CRAYFISH CAMBARUS SPHENOIDES
Physical description: The ischia of the third maxilliped have no teeth on the mesial border. The first pleopod terminates in two elements bent at no less than 90 degrees to the principal axis of the shaft of the appendage. The antennae are not conspicuously fringed on the mesial border, and the lateral margin of the fixed finger is never serrate. The eyes are with facets and always pigmented. The central projection of the first pleopod is bent caudally at an angle of at least 90 degrees to the principal shaft of the appendage. The fingers of the chela have moderate to strong dorsal longitudinal ridges. The fingers are seldom widely gaping and always lacking the prominent cluster of plumose setae at the base of the fixed finger. The palm of the chela has two or more rows of tubercles along the mesial margin, often with additional tubercles dorsolateral to two rows. The mesial margin of the palm of chela has a row of fewer than eight tubercles. The dactyl of the chela is lacking the broad concavity on the basal half of the opposable margin. The first pleopod has a central projection distinctly longer than the cephalocaudal diameter of the shaft at the base of the projection. The first pleopod with the central projection has a subapical notch. The areola have two or three punctations across the narrowest part. The rostrum does not have marginal spines or tubercles. The dorsal surface of the palm of the chela has many squamous tubercles. The areola are usually at least five times longer than broad *SP02*. REPRODUCTION: eggs develop attached to female and hatch as small adults forms *866*. Adult male crayfish exist in breeding (Form 1) and non-breeding (Form 2) stages. Form 1 males have one or more corneous projections from the distal ends of the first pair of abdominal appendages (pleopods or swimmerets), sperm ducts full of sperm, and hooks on the bases of certain walking legs *SP04*. Copulation is initiated when the male "inverts the female and holds her with his body, chela, and telson, and transfers his sperm from the openings of his vasa deferentia to her seminal receptacle by the means of the first two pairs of his swimmerets". This process may take from a few minutes to several hours *SP05*. Ferilization occurs late in the breeding season as the female releases her eggs into a mucilaginous sac where they are mixed with the sperm *SP04*. The fertilized eggs are attached to the swimmerets during development. Ferilization does not occur at any specific time of the year, although it usually occurs between spring and early fall. The male seems to have no abililty to distinguish between sexes *SP05*. Ovarian maturation is dependent on temperature, photoperiod, and hormonal balances *SP04*. The young go through three instar stages, and sexual maturity is reached by the spring molt of the year following hatching in both sexes *SP05*. Behavior: The young remain attached to the female by a telson thread from the egg sac. By the third instar, they leave their mother to go exploring. Brooding females are less active than other adults, and hide under stones in debris, undercuts, and burrows. They communicate with their young via pheromones. Growth depends upon food availabilty, water quality, temperature, and predation pressure *SP04*. Crayfish are omnivorous, and they prefer fresh animal and plant material to stale material *SP05*. They will consume worms, insects, insect larvae, fish, frogs, toads, and salamander eggs *SP06*. They have also been been known to consume supplemental foods, such as soybean meal, fish meal, cracked corn, potatoes, and dry or fresh hay *SP07*. Detritus and microbiota are probably the major components of their diet *SP04*. +hey do not react to stationary objects, but do react to large moving objects as a result of changing light intensity *SP22*. They are nocturnal *SP23*. Crayfish have a highly developed topochemical sense, but they do not respond to sound *SP22*. They are aggressive, and they have a home range of probably less than 100 feet *SP25*. Size is directly related to dominance in male and female adults, but not in juveniles *SP26*. Limiting factors: Crayfish can acclimate to increasing temperatures *SP05*, and have a high relative heat tolerance *SP21*. In the lab, increased photoperiods resulted in increased mortality *SP30*. Population parameters: Crayfish usually have two to four molts after the first mating before they die *SP28*. More males than females die after sexual union *SP29*. The mean number of ovarian eggs is directly propotional to body size *SP04*. Aquatic/terrestrial associations: Predation is by 22 fish species, seven amphibians, three reptiles, and six birds *SP12*. In addition, they are preyed upon by the otter, opossum, mink, and muskrat *SP27*.
| Life History |
References for Life History Codes
866, SP02, SP04, SP05, SP06, SP07, SP22, SP23, SP25, SP26, SP21, SP12, SP27, SP30, SP28, SP29
Comments on Life History Codes