Marine Mammal Neurology & Special Senses

Question 1

What portion of the brain is well developed, similar to primates?

Why is cerebrospinal fluid difficult to acquire from cetaceans?

Answer 1

• Nervous
  
  • Brain: well-developed temporal lobes like higher primates
  • Cetacean and sirenians: cervical and thoracic spinal cord surrounded by epidural AV retia – difficult to obtain CSF

Question 2

What is the melon?

How does it differ between dolphins and porpoises?

How is sound generated within it?

What is the function of the intermandibular fat body?

Describe the anatomy of the goosebeak and how its function in communication.

Answer 2

• Communication
  
  • Melon: rostral fat pad, contains collagen 🡪 important for echolocation
    
    • Porpoise vs dolphin: porpoise melon extends to rostral margin of maxilla
    • Physiology: made of lipid & connective tissue; focus sound and decrease acoustic attenuation at tissue-water interface (McKenna 2011 Marine Mammal Science)
  • Intermandibular fat body - conducts external sounds to ears; innervated by branch of trigeminal nerve; important to maintain structures during dental, oral and rostral surgical procedures
  • Goosebeak: important for production of sound, modified portion of larynx, elongated epiglottis and corniculate cartilage of the arytenoids, extends through small opening in the roof of the pharynx