Name
Period
Crayfish Dissection
http://www.youtube.com/watch?v=W7F0jZgdc8A
http://shs2.westport.k12.ct.us/mjvl/biology/dissect/crayfish.htm
External Structures---Do this section BEFORE you cut.
1. Note that the body of the crayfish is divided into two parts: the ______________
and the
2. The compound
head.
.
are sticking out on the eyestalk on rostrum portion of the
3. What is the difference between the antenna and the antennule?
4. Cephalothorax - What is the covering of the cephalothorax region called?
5. There are
(number) pairs of walking legs connected ventrally to the carapace.
The first walking leg has enlarged pincers called_________________ (claw), and is used to
manipulate objects and capture and crush food.
6. The abdomen is a segmented tail. On the ventral side there are __________
(number) swimmerets.
7. On the ventral side, the mandibles tear the food, and the other appendages detect and hold
food during feeding. Draw the mouth area and Label the feeding appendages. (5 points)
8.
Check each item as you find it. (15 points)
Illustrate Mouth area and feeding appendages
Internal Structures---Lay your crayfish on the Dorsal side. Cut open the Crayfish
by using the scissors to cut around the carapace and between the legs on the Ventral
side. This will expose the internal organs.
1. Respiratory System -- The
_________
(respiratory organs) are located on
the outside of the body cavity in a space between the body wall and the carapace.
2. Detach one of the walking legs and note the small
gill that is attached to the
leg. Place
the gill section on a microscope dish and observe
under the microscope. Illustrate what you see
here. (5 points)
3. Nervous System -- Locate a pair of nerves leading from the ventral nerve cord around the
esophagus to the large ganglion, or
, in the head. Short nerves
connect the eyes, antennae, and antennules to this brain.
4. Circulatory System -- Locate the diamond shaped
of the open
circulatory system. This organ pumps blood into the spaces around the organs.
5. After passing through the
, where oxygen and carbon dioxide are
exchanged, the blood drains back into the heart.
6. Check each body part or organ as you find it. (10 points)
Ganglion or
Brain
Gills attached to
walking legs
7. Illustrate and describe the most interesting thing you observed. (5 points)