Crayfish is in the Subphylum
Crustacea, Class Malacostraca, order Decapoda,
constituting the superfamilies Astacidae and Cambaridae
(Northern Hemisphere) and Parastacidae (Southern Hemisphere in Australia,
New Zealand, South America, and Madagascar). They are characterized by
a joined head and thorax, or midsection, and a segmented body. They
grow by molting as all crustaceans do, i.e., they shed their carapace (shell)
when they outgrow it, and form a new hard shell. There are over 540
species worldwide, and nearly half of the number in North America.
Most of them live in fresh water, a few in salt water, and even in underwater
caverns (including Troglobitic
crayfishes). The color and size vary with species, diet, and age.
Most are red, some are green, brown, tan, or blue with black or orange
markings in various combinations (except those in the caverns). Juveniles
often are light tan, and turn deep red when grow up. The coloration
depends in part on their diet, and can change with a change in diet.
Adult size is 2" to 6" for most US species. Some Australian varieties
can alos be quite big. Among the largest is Astacopsis gouldi
of Tasmania in Autralia, which may reach 40 cm and weigh about 3.5 kg (8
pounds). The pictures of two species of Procambarus shown
below. We have been "playing" with these creatures from
Louisiana (Procambarus spp.) for a while. We "milk" them
to get their digestive fluid, from which the endopeptidase astacin
is isolated.
Do you want to know what
about crayfish outside our lab? (Hmm!)
The "Crayfish Home Page"
http://www.utexas.edu/depts/tnhc/.www/crayfish/crayhome.html
which has recently moved to
http://bioag.byu.edu/mlbean/crayfish/crayhome.htm
The International Association of Astacology
(Yes, things about Astacus)
http://www.uku.fi/english/organizations/IAA/
Some brief information and links
http://www.sonic.net/daltons/melissa/crayfish.html
Several links in the "Freshwater Resources"
Aqualink
http://www.aqualink.com/fresh/z-crayfish1.html
http://www.aqualink.com/fresh/z-crayfish2.html
http://www.aqualink.com/columns/k-crayfish.html
http://www.aqualink.com/columns/k-crayfish1.html
http://www.aqualink.com/columns/k-crayfish2.html