Marine Mammal Dermatology

Question 1

What is unique about the integument of cetaceans?

Describe the structure of blubber.

Answer 1

• Integument
  
  • No hair follicles
  • Blubber: reticular dermis grades into fat-filled panniculus adiposus; contains collagen bundles, elastic fibers, adipocytes (ensures blubber won’t diminish significantly during catabolism)
    
    • Thickened dermis
    • Inner half of thoracic blubber = catabolism
    • Outer half of thoracic blubber + all of tailstock blubber = structural

Question 2

Describe the structure of pinniped skin.

How does skin structure vary between otarrids and phocids and odobenids?

Answer 2

• Otarrid Integument
  
  • Robust vibrissae
  • Fur + blubber for streamlining and insulation
  • Compound hair follicles (single guard hair, multiple intermediate + underfur follicles)
  • Well-developed apocrine and sebaceous glands
  • Thin blubber, thick haircoat
• Phocid Integument
  
  • Epidermis: lobulated “scale-like” pattern that helps reduce drag
  • Elephant + monk seals: simple hair follicles
  • Glomeruloid arteriovenous anastomoses in dermis; helps with thermoregulation
  • Catastrophic molts may occur – granular cell layer forms, surface epithelium shed in large sheets
• Odobenids
  
  • Simple hair follicles

Question 3

Describe the integument of manatees.

Do they have hair?

Answer 3

• Integument
  
  • Skin denser than water 🡪 negative buoyancy
  • Body hairs sparse, short, innervated (detect hydrodynamic stimuli)

Question 4

What is unique about sea otter skin structure?

Answer 4

• Compound hair follicles (single guard hair, multiple intermediate + underfur follicles)
• Well-developed sebaceous and apocrine glands
• Thin blubber, thick hair coat