FRESHWATER MACRO INVERTEBRATES
Click on this PDF to read a great article about crayfish!!!
Click on this PDF for some more crayfish info
There are 315 species of crayfish in North America. The average life span of a crayfish is between 2-6 years, but crayfish may live longer in captivity when they are well cared for. Crayfish prefer shallow, cool, running bodies
of water. Crayfish are considered facultative to most forms of pollutants. They are however sensitive to some toxic substances including metals and insecticides. Crayfish are omnivores and will eat small fish, tadpoles, other invertebrates and also dead plants. Some crayfish dig underground burrows to live in throughout the late fall and winter.
There are about 69 species of leeches in North America. Leeches are segmented worms. They are most commonly found in freshwater, but there are a few species of marine and terrestrial leeches as well. All leeches feed on the fluids of other organisms, but some pierce and kill their prey to obtain the fluid and others are parasitic and suck fluid from their pretty, but seldom kill them. Leeches move by anchoring themselves to the ground, rocks or other items using their suckers both front and back. Leeches have been used in medicine to help with blood flow as well as research for anesthetics.
Click on this link for some great information on dragonflies from the book: Bugs and Bugsicles
There are 300 different species of dragonfly living in North America. Depending on the species, dragonflies can be in all three taxa for water quality. The green darner dragonfly is very sensitive to pollution, the club-tail dragonfly is somewhat tolerant, and the pennant dragonfly is tolerant. Most people believe that dragonflies sting, but they are actually not capable of stinging and are quite harmless to humans. Click the links below for some great dragonfly resources.
There are about 1400 species of caddisflies in North America. Caddisflies are aquatic as larvae and pupae and terrestrial as adults. This means that they live in the water as young and on land as adults. Most caddisflies are sensitive to pollution, but there are a few species that can be more tolerant. Caddisflies are extremely important in the aquatic ecosystem as they provide food for many species of fish. Caddisflies are also extremely important when studying pollution in freshwater. Most species of caddisflies are nocturnal and spend their days hiding in moist environments. All caddisfly larvae produce silk which they use to build protective shelters. The free living caddisfly only constructs shelter for the purpose of pupation.
There are about 500 species of freshwater snails in North America. Snails are divided into two groups, gilled snails also called prosobranchs and lunged or pouch snails also called pulmonates. Due to the way they breathe, gilled snails are more sensitive to pollution in freshwater systems.
A great resource for information on all macro invertebrates is: A Guide to Common Freshwater Invertebrates of North America by J. Reese Voshell, Jr.
Photo credit for all critter pictures to scientific illustrator Gina Mikel please visit her website at http://www.scientificillustrator.com to see more great images and learn about her work.