======Shark Dissection======


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**Alternative titles:** Dogfish Shark Dissection (Squalus acanthias)
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====Summary====                   
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====Procedure====  
  *Follow instructions provided in the links below.




====Links==== 
Best Dogfish Shark Dissection: Part I - External (Jr. High, High School and College) - SDPB: 
{{youtube>BBfdzpdNh70?}}\\

Demonstration: Shark Dissection - Arizona Science Center: 
{{youtube>0Y9jpGK3en0?}}\\

📄 SHARK DISSECTION - Mayfield Schools: [[https://www.mayfieldschools.org/Downloads/Shark_dissection.pdf]]\\

📄 Virtual Shark Lab - Phoenix College: [[https://www.pc.maricopa.edu/Biology/ppepe/BIO145/lab04.html]]\\

====Variations====
  * Consider doing a virtual dissection instead.
  *Compare male and female specimens, documenting claspers and reproductive tract differences.
  *Examine injected specimens (arterial, venous, portal) to map circulatory pathways.
  *Dissect a bony fish for comparison and create a table contrasting cartilage vs. bone, tail form, scales, and swim bladder presence.
  *Open and rinse the spiral intestine to visualize the internal valve and estimate surface area increase.
  *Prepare a nervous system focus lab that only exposes brain regions and cranial nerves.



====Safety Precautions====
  *Wear gloves and a lab coat; work in a well-ventilated area or fume hood when possible.
  *Use scissors for most cuts; if a scalpel is needed, make shallow, controlled strokes on the tray and cut away from hands.
  *Beware of sharp dorsal fin spines; remove or pad as directed by your instructor.
  *Handle preserved tissues and fluids as potential irritants; avoid skin and eye contact and keep food and drink out of the lab.
  *Do not remove organs with force; use a blunt probe to free connective tissue to avoid accidental cuts.
  *Dispose of tissues as biological waste and blades in approved sharps containers; disinfect tools and benches after use.
  *Brain exposure should be instructor demonstration only due to risk of damaging underlying structures.




====Questions to Consider====
  *What advantages does a heterocercal tail provide for a shark’s swimming and buoyancy? (It generates lift and thrust to counteract negative buoyancy.)
  *How are placoid scales related to shark teeth in structure and origin? (Teeth are modified placoid scales derived from similar dermal tissues.)
  *What is the functional difference between epaxial and hypaxial muscles during swimming? (Epaxial control dorsal flexion and stabilization; hypaxial contribute to ventral flexion and lateral undulation.)
  *Why does the spiral valve increase efficiency in the shark intestine? (It lengthens the absorptive path and increases surface area for nutrient uptake.)
  *Trace the path of blood through the shark heart chambers you identified. (Sinus venosus → atrium → ventricle → conus arteriosus → gill capillaries.)
  *How does the rectal gland help maintain internal salt balance? (It actively secretes excess NaCl into the gut for elimination.)
  *What osmoregulatory role does urea play in sharks? (High blood urea elevates osmotic pressure to approximate seawater, reducing water loss and salt gain.)
  *Which external features help the shark sense its environment? (Lateral line detects water movement; nostrils and olfactory lobes detect dissolved chemicals; eyes and spiracles aid feeding and respiration.)