The Crayfish

By Al Lowe
Contributor

There are a lot of strange looking animals in the world. This is one of them.
Almost everyone knows what they look like. Here in Northwestern Ontario, most kids call them crabs. But they aren't crabs - and they aren't lobster, either. They look like - well - crayfish. If you took science in high school, I'm sure you will remember dissecting one of these.
The crayfish has 19 pairs of 'appendages,' things which are attached to its body. Some of these are for sensing motion, for instance, and some (mandibles) are for eating. Some hold gills. Some are walking legs - 4 pairs of them. And the major pair are those big pincer types which, in the lobster, we call claws. Three of the pairs are used for reproduction - transfer of sperm, or for the attachment of eggs. The last set are fused together to form the flat 'telson,' which can enable the crayfish to move backward at a very rapid clip.
There are over 100 different species of crayfish in the world. Ours is quite a small one. Some of the others are quite big, and can be caught and eaten. Quite good, too!
Crayfish generally live in the water - under weeds and stones - dark places. They usually come out at night. When they are still, or hiding, they face out, so those big claws can protect them. Some fairly large species do live in wet, swampy places. These are mostly in the eastern U.S. and are the legendary 'crawdads' you have heard about.
Crayfish have some very odd things about them. Here are a few. For one thing, those 'appendages' can be regenerated. If one is broken off, it just grows back again. Look at an adult. Chances are one of those big claws is smaller than the other - regeneration! If one of its walking legs get caught in some rocks, the crayfish just breaks it off, and grows a new one.
Here are a few other things. Its eyes are on little stalks, so the it can look around in all directions without moving. Its eggs are attached to its mother, and young ones stay attached to 'mom' for over a month. The crayfish can easily walk in all four directions. It sheds its skeleton as it grows, and the new one hardens in about a day. It has little pits in its head, which it fills with fine sand. This acts as its balancing organ.
Crayfish walk slowly, but they move backward at an amazing speed. If you want to catch one, put your hand behind it, then scare it from the front.
The crayfish, like the lobster, is a scavenger. Most of its food is already dead, but it can catch small fish and insects. In turn, it is eaten by almost every animal which is bigger than it is.
The crayfish, Cambarus species, is familiar to anyone who has even taken a course in general biology. It is an Arthropod, and, since arthropods are about 75% of all the animals on earth, dissecting this animal gives you an insight into a lot of the animals we have.
Besides that, it is an integral part of the food chain in a large part of the world.