Saddleback Crayfish

Media
Photo of a saddleback crayfish.
Scientific Name
Faxonius medius (formerly Orconectes medius)
Family
Cambaridae (freshwater crayfish) in the order Decapoda (shrimp, crabs, and lobsters)
Description

The most obvious feature of the saddleback crayfish is its bold blackish band (saddle mark) across the hind margin of the carapace; note also the absence of dark blotches or specks. The overall color is olive tan. Another dark bar crosses the head just in front of the cervical groove (the groove separating head from thorax). The pincers are broad and powerful; they are a uniform reddish tan and lack mottling or spots.

Similar species: Within the range of this species are the golden crayfish, which has a darker abdomen and red on many body parts, and the belted crayfish, in which the forwardmost saddle spans the cervical groove.

Common Name Synonyms
Saddlebacked Crayfish
Size

Adult length: about 1 to 2½ inches.

Where To Find
Saddleback Crayfish, Saddlebacked Crayfish Distribution Map

Confined to the Ozark Region of Missouri, where it is found only in the Meramec River and Big River drainages, but not in the adjoining Bourbeuse drainage.

Occurs most often in small to medium-sized creeks having clear, permanent flow and stable, rocky bottoms. This crayfish digs shallow burrows beneath rocks. In many small streams where it is found, it is the most abundant crayfish.

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

The saddleback crayfish is endemic to Missouri: it occurs within our borders and nowhere else in the world.

Life Cycle

Like most other Ozark stream crayfish, this species has a fall breeding season and a spring reproductive season. Eggs are produced in early spring and are carried beneath the mother's abdomen. Females are secretive during this time. After the young hatch, they continue to hold on to the mother's tail until they are able to start being independent. Some young reach maturity in their first year of life. Saddleback crayfish can live for about 3 years.

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.

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.

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About Aquatic Invertebrates in Missouri
Missouri's streams, lakes, and other aquatic habitats hold thousands of kinds of invertebrates — worms, freshwater mussels, snails, crayfish, insects, and other animals without backbones. These creatures are vital links in the aquatic food chain, and their presence and numbers tell us a lot about water quality.