Crayfish biology, (some) and identification

Crayfish

Crayfish Phylum: Arthropoda Subphlum: Crustacea Class: Malacostraca Order: Decapoda

Crayfish Order: Decapoda Families: Parastacidae (South America & Australia) Astacidae (Pacific Northwest, Western Asia, & Europe) Cambaridae (North America & East Asia)

How many crayfish are there? 640+ worldwide 350+ North America (mostly Cambaridae)

How many crayfish are there?

640+ worldwide 350+ North America (mostly Cambaridae) 17+ Indiana

Crayfish Biology Four main habitats occupied by crayfish:

Crayfish Biology Four main habitats occupied by crayfish: Primary burrowers, stream-dwellers, lake/big river/secondary burrowers, and cave-dwellers

Crayfish Biology Each type has distinctive morphological adaptations for their ecosystems (to be continued)

Crayfish Biology Primary burrowers: Typically have larger gill surface and robust chelae Stream specialist: Larger abdomen for swimming and are intolerant to low DO Cave species: Loss of pigment and eyes, elongated limbs and antennae

Crayfish Biology Life ~2-20 years Reproduce sexually Nocturnal omnivores Crayfish shed for growth and reproduction Most are 2”-6” Some are much larger 

Crayfish importance Often process detritus to make nutrients available to other species Omnivores: Feed on detritus, minnows, invertebrates, plants, etc. Prey for many fish, bird, mammal species Ecosystem engineers

Crayfish negative impact Many species are invasive and have a huge negative impact on native species and their ecosystems. Two of the most common invasive crayfish are native to Indiana. Rusty crayfish (Orconectes rusticus) Northern (Virile) crayfish (Orconectes virilis)

Crayfish negative impact Many species are invasive and have had a huge negative impact on native species and their ecosystems. Two of the most common invasive crayfish are native to Indiana. Rusty crayfish (Orconectes rusticus) Northern (Virile) crayfish (Orconectes virilis) Before we learn how to identify groups of crayfish, we need to understand the crayfish lifecycle and anatomy.

Crayfish life cycle Males have a reproductive form (I) and a non-reproductive form (II). Most identification keys are based on form I males.

Crayfish molting with abdomen detatching from tail.

Crayfish life cycle Reproductive male finds receptive male and ……………

Crayfish life cycle Reproductive male finds receptive male and ……………

Crayfish life cycle

Crayfish anatomy Crayfish anatomy is very important for identification Species, gender, and form Identifying subtle differences among individuals helps distinguish crayfish species

Crayfish anatomy

Males Females

Crayfish anatomy Males Form I vs. Form II

Crayfish identification Once the gender and form has been determined you can begin to identify your crayfish. Major structures that are important for identifying crayfish Claws Gonopods Rostrum

Crayfish anatomy Their large anterior-most pairs of legs have powerful claws which are efficient tools for defense, food gathering, and object manipulation.

Crayfish anatomy Gonopods are used to fertilize females

Crayfish anatomy Rostrum: The "nose" of the crayfish; the portion of the carapace on the head region that is anterior to the eyes. Thought to be protection of the brain and eyes.

Crayfish identification To keep it simple we are going to go over the identification of rusty crayfish and virile crayfish vs. others.

Crayfish identification Orconectes:

Crayfish identification If Orconectes, we take a closer look at the gonopod

Crayfish identifcation If Orconectes, we take a closer look at the gonopod

Crayfish identification Crayfish identification is not easy. If you would like to learn more about crayfish and their identification, contact me after class and I would be happy to give you more resources.