Crayfish Dissection

Crayfish are found in fresh water like streams, ponds, and ditches. This organism prefers to live in non-polluted water. They can be found under rocks of small streams and creeks. Crayfish eat both plants and animals. They will also eat dead organisms that are relatively fresh. Examples of their diet include worms, insects, insect larvae, and eggs of other organisms. Crayfish are able to live despite hostile conditions due to the wide range of food they are able to consume. Also their ability to consume detritus allows energy transfer of organisms. Crayfish have gills that allows them to retrieve oxygen from water. Crayfish may breathe outside of water if and only if their gills remain moist. In other words, crayfish living in humid environments are able to spend time outside of water. Crayfish can live up to 20-30 years if they hide in holes and do nothing. They reach maturity after 4 years.

Major External Anatomy

Eyes- capture light for vision
Antenna- sensory appendages used to sense food and surroundings
Cheliped- 1st pair of walking legs used for grasping and defense
Walking legs- appendages used for movement
Abdomen- segmented region used to swim backwards
Swimmeret- used for reproduction
Rostrum- protects the sensory appendages of the face
Telson- central swimming paddle
Uropod- small swimming paddles

Green Gland- excretes waste products and balances water in blood
1st-2nd maxilliped- holds food
Mandible- crushes food

We are able to determine the sex of our crayfish by looking at the first set of swimmerets. Males have larger 1st swimmerets to hold the female during mating. They are labeled in blue on the image.

Incision Guide

Begin by cutting along the carapace as shown in the top image. Start from the sides closest to the abdomen and cut towards the head of the cray fish following the curves depicted. Try to cut along the indentations already present on the carapace. Extend the cut closer to the cephalic region. The bottom image shows the cuts made when the crayfish is on its side. Cut from the abdomen towards the cephalic region from the top side first. Then perform the same cut along the bottom side. The image uses highlighted blue markings to demonstrate that this bottom cut should occur without cutting the walking legs.  These legs should be pushed aside to perform this cut.

Major Internal Anatomy
The picture below is kind of blurry. Red highlights are the gills which are used for breathing. The green highlight is the stomach which is used to digest food. The blue highlight is the digestive gland which produces digestive enzymes. The purple is the midgut which is part of the intestines and absorbs nutrients. the yellow is the ventral nerve cord which connects the brain to the rest of the body. The intestines prepare food for secretion. The tail muscles are used for swimming.

Dissection Video

https://www.youtube.com/watch?v=D4gdFtXlvG4