2010
United streaming: crayfish 10:44
Youtube- crayfish external anatomy http://www.youtube.com/watch?v=rZ-7LF5AkGs 6.21
internal http://www.youtube.com/watch?v=rpkiNLhCBMU&feature=related 9.47
Crayfish Review http://biog-101-104.bio.cornell.edu/BioG101_104/tutorials/animals/crayfish.html
Label digrams
Prelab questions
1

• Kingdom-Animalia
• Phylum-Arthropoda
• Class-Crustacea
• Order-Decapoda (10 feet)
• Family-Astacidea
• Genus-Cambarus
• Species-affinis
2

• Body is divided into 2 regions:
• 1. Cephalothorax (the head and carapace)
• 2. Abdomen (posterior portion of body)
• Label the uropods, chelipeds, antennae, and antennules
3

Appendages:
• Crayfish appendages are biramus – branched – and jointed
• 7 pairs of feeding appendages, including the mandibles and chelipeds.
• Antennules contain hearing and balancing mechanisms
• Antennae contain organs of touch, taste and smell
• Swimmerets are abdominal structures for swimming
• Walking legs are thoracic structures for walking
4

• In nearly all bodies of fresh water that contain lime
• Why would lime be important to the crayfish?
--used to harden the exoskeleton of chitin
• What adaptations do crayfish show for their aquatic habitat?
5

• They have gills as their respiratory organs.
Gills take in oxygen from water and pass carbon dioxide back to the water
• The gills can hold oxygen for a long time once the crayfish is out of the water
What are the gills attached to?
–the walking legs
6

• Use telson, uropods, & swimmerets to swim backwards
• Use walking legs (4 pairs) to crawl over the bottom
• 5th pair of walking legs (crayfish are decapods) is modified as the chelipeds (pincers/claws)
7

• Omnivorous
• fish & shrimp larvae
• pond vegetation
• small water insects
8

1. Mandibles move from side to side to crush food as
2.it enters the mouth
3.Food then passes through the esophagus to the
4.cardiac stomach, where it is ground up (part of the stomach is lined with “teeth”).
5.Food then passes through the digestive glands and for digestion and temporary storage.
6.Undigested food travels through the intestine and is eliminated through the anus
9

10

• The green gland is located internally just behind each antenna and right under the brain. These structures filter fluid waste from the blood
• The green glands are analogous to what human structure? _kidneys_
• Based on the crayfish’s habitat, do you think the green gland retains salt in the body of the crayfish, or excretes salt to osmoregulate?
 Retain salt
• Nitrogenous waste exits the body through nephridiopores into the surrounding water.
11

12

• reproduce sexually, sexes are separate, and fertilization is internal:
Males – testes (white) produce sperm that exit the body through a pore at the base of the 5th pair of walking legs
Females – ovaries (orange) produce eggs which are released after internal fertilization through a pore at the base of the 3rd pair of walking legs
• Females usually have 10-800 eggs, which hatch in 2-20 weeks, depending on the water temperature.
• Eggs are retained until mature on the swimmerets of the female
• An average crayfish life span is 3-4 years
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14

• located on the ventral side of abdomen (used for swimming and for reproduction)
• Difference between males and females:
• Females: crescent shaped slit; are all soft to the touch
• Males: sperm duct opening (actual pore); hard to the touch
15

• The male’s gonads are very difficult to find
(they are located underneath the heart)
• The ovaries are yellow/orange. They are located just below the carapace.
16

• Heart – located on dorsal side just below digestive glands
• Open circulatory system
17

• Large nerves travel from brain to ventral part of body
• A _ventral nerve cord is present
• Compound Eyes with more than 2,000 lenses
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