======Crayfish Dissection======


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**Alternative titles:** Arthropod Anatomy: The Crayfish
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====Summary====                   
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====Procedure====  
  *Follow instructions provided in the links below.



====Links==== 
Crayfish Dissection || Aw Snap! [EDU] - Silvergrass Institute: 
{{youtube>s2p1KmqUlTY?}}\\

📄 Crayfish Dissection - PBS Learning Media: [[https://www.pbslearningmedia.org/resource/047ec6ad-11a0-447b-8802-240dcc1a2758/dissection-101-crayfish-dissection-lesson-plan/]]\\

📄 Anatomy of a Crayfish - Biology Corner: [[https://biologycorner.com/worksheets/anatomy_crayfish_virtual.html]]\\

====Variations====
  *Compare freshwater crayfish with a crab or shrimp and record similarities and differences in gills, appendages, and carapace.
  *Inject a small amount of colored water near the mouthparts to visualize gill ventilation across the branchial chamber.
  *Focus study: dissect only the stomach to examine the gastric mill in detail and relate form to function.
  *Use an interactive quiz or pinned practical the next class to reinforce identification.



====Safety Precautions====
  *Wear gloves, eye protection, and protective clothing; keep an eyewash and spill cleanup materials available.
  *Use scissors for most cuts; if a scalpel is needed, make shallow, controlled strokes on the tray and cut away from fingers.
  *Handle preserved specimens and fluids as potential irritants; work in a well-ventilated area and avoid skin and eye contact.
  *Keep food and drink out of the lab; wash hands after cleanup.
  *Dispose of biological waste and blades in approved containers; disinfect instruments and benches after use.




====Questions to Consider====
  *Which features identify crayfish as arthropods? (Exoskeleton, jointed appendages, segmented body, and paired appendages)
  *How do swimmerets differ between males and females, and what are their functions? (Males have enlarged hardened first swimmerets for sperm transfer; females use swimmerets to carry eggs and aid ventilation)
  *Where are the gills located and how are they ventilated? (Inside branchial chambers under the carapace; water is drawn across feathery gills by mouthpart movements)
  *What is the function of the gastric mill in the cardiac stomach? (It mechanically grinds food before it passes to the pyloric stomach and midgut)
  *How does the open circulatory system differ from a closed system? (Hemolymph leaves vessels to bathe tissues in sinuses; a dorsal heart pumps it back into arteries)
  *What structures power the rapid tail-flip escape response? (Large abdominal extensor and flexor muscles attached to the tail fan)
  *Where are the excretory organs and what are they called? (Green or antennal glands at the base of the antennae; they remove wastes and regulate ion balance)