fill the blanks Transcribed Image Text: (intel 9. Locate the 1st pair of walking legs or periopods. These are called the chelipeds (the claws). Gently

Best Writers Biology fill the blanks Transcribed Image Text: (intel 9. Locate the 1st pair of walking legs or periopods. These are called the chelipeds (the claws). Gently

Biology

fill the blanks Transcribed Image Text: (intel 9. Locate the 1st pair of walking legs or periopods. These are called the chelipeds (the claws). Gently

fill the blanks Transcribed Image Text: (intel
9. Locate the 1st pair of walking legs or periopods. These are called the chelipeds (the claws).
Gently manipulate the cheliped to determine the direction in which the appendage can bend.
How many joints are there on a single cheliped?
10. Cut the end of the cheliped off and use the forceps to find the connective tissue inside. Pulling
on this tissue will make the claw open and close. Try it!
11. Behind the cheliped are four more pairs of walking legs. Remove one of these and compare
them to the cheliped. How many joints are on each walking leg?
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12. Locate the swimmerets or pleiopods. Are the swimmerets jointed?
How many pairs of
swimmerets are there?
13. The last segment of the abdomen (the 7th segment) is called the telson, and it is specialized
for swimming. Locate the two uropods extend from either side of the telson.
Craynsh
14. Look at the first pair of swimmerets on your crayfish. If these swimmerets are considerably
larger and stiffer than the other swimmerets, you have a male. If the first swimmerets are about
the same size as the others, your crayfish is a female. What is the sex of your crayfish?
15. Carefully insert the point of the scissors under the top of the carapace (shell) at the back of the
cephalothorax and cut up the middle to the rostrum. Gently split and peel away the carapace being
careful not to remove any internal tissues
16. Note the exposed gills. (Feathery like structures just under the carapace you just removed)
17. The two light colored masses extending on each side of the body into the head is the digestive
glands (hepatopancreatic glands). In between these masses, just behind where the rostrum used to
be is a large, thin-walled stomach. It may be filled with the crayfish’s last meal. Open the stomach
and observe the contents. If empty, you may be able to see three small brown “bumps”. These are
known as the gastric mill and are used to physical grind the food inside of the stomach.
18. Just posterior to the stomach is a very small heart. Carefully remove the heart and observe it
under a dissecting scope. You may want to place it in a petri dish of water. Can you see the ostia?
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