1. Crayfish Prelab 2010 United streaming: crayfish 10:44 Youtube- crayfish external anatomy http://www.youtube.com/watch?v=rZ-7LF5AkGshttp://www.youtube.com/watch?v=rZ-7LF5AkGs 6.21 internal http://www.youtube.com/watch?v=rpkiNLhCBMU&feature=relatedhttp://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

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

3. What do crayfish look like? External Anatomy (Dorsal View) 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

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

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

6. Respiration 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

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

8. What do crayfish eat?What do crayfish eat? Omnivorous Omnivorous fish & shrimp larvae fish & shrimp larvae pond vegetation pond vegetation small water insects small water insects 8

9. Tracing food through the crayfishTracing food through the crayfish 1. Mandibles move from side to side to crush food as 2.it enters the mouth2.it enters the mouth 3.Food then passes through the esophagus to the3.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

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11. Excretory System: The Green GlandExcretory System: The Green Gland 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 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_ 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? 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

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13. Reproduction reproduce sexually, sexes are separate, and fertilization is internal: 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. 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 Eggs are retained until mature on the swimmerets of the female An average crayfish life span is 3-4 years An average crayfish life span is 3-4 years 13

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

16. Internal Male & Female structuresInternal Male & Female structures The male’s gonads are very difficult to find (they are located underneath the heart) 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. The ovaries are yellow/orange. They are located just below the carapace. 16

17. Circulation of the CrawfishCirculation of the Crawfish Heart – located on dorsal side just below digestive glands Heart – located on dorsal side just below digestive glands Open circulatory system Open circulatory system 17

18. Nervous SystemNervous System Large nerves travel from brain to ventral part of body Large nerves travel from brain to ventral part of body A _ventral nerve cord is present A _ventral nerve cord is present Compound Eyes with more than 2,000 lenses Compound Eyes with more than 2,000 lenses 18

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