Vernal Crayfish

Procambarus viaeviridus

vernal_crayfish.jpg

Photo of a vernal crayfish.
In Missouri, the vernal crayfish is found only in our southeastern swamps, and then usually only seen in February and March.
Chris Lukhaup
Species of Conservation Concern
Family

Cambaridae (freshwater crayfish) in the order Decapoda (shrimp, crabs, and lobsters)

Description

Adult vernal crayfish are rust red with a blackish wedge-shaped central stripe along the length of the abdomen. The carapace is smooth and is separated at the middle by a narrow space (areola). The rostrum is broad and lacks a central troughlike depression and lacks lateral notches or spines near its tip. The pincers are moderately long and slender.

Other similar crayfish within the range of the species are the red swamp crayfish and the White River crayfish. These species have a narrower rostrum (often with lateral spines) and a granular (roughened) carapace.

Size

Adult length: about 1¾ to 3 inches.

Habitat and conservation

"Vernal" means "springtime." In February and March, when water levels are high, this crayfish is found in shallow, seasonally flooded swamps, sloughs, and other depressions. It avoids flowing-water habitats. As water levels recede in late spring and early summer, it retreats into burrows, not to be seen again until the next wet-weather period.

Foods

Crayfish are generally omnivores, eating a wide variety of plant and animal materials.

image of Vernal Crayfish Distribution Map
Distribution in Missouri

The vernal crayfish occurs in the lowlands of southeastern Missouri as far north as Bollinger County. Most records are concentrated along the Ozark border in Ripley, Butler, and Stoddard counties.

Status

A Species of Conservation Concern in Missouri. In our state, the distribution of this species is centered in the least disturbed areas of our Bootheel swamps, and it was probably more widely distributed before that part of Missouri was ditched and drained. This species' range extends southward on both sides of the Mississippi River as far as eastern Alabama and northern Louisiana.

Life cycle

The appearance of small juveniles in January and February probably means that reproduction occurs in the fall. The life span apparently is about two years. “Vernal” means springtime and refers to the life cycle, since this crayfish stays in burrows most of the year and is usually only seen in early spring.

Human connections

In addition to feeding many types of wildlife, crayfish provide food for many species that humans hunt and fish. Crayfish commonly serve as fish bait, and many people eat crayfish, too. Crayfish are fascinating, colorful creatures in their own right, and part of our rich native heritage.

Ecosystem connections

Crayfish are an important link in the food chain between plants and other animals, breaking down plant materials that are resistant to decay. Crayfish in turn are an important food for many other animals. Presence of crayfish in a stream or pond usually indicates good water quality.