Table 3 Presence of structures/characteristics of the pinniped skin
From: Skin histology and its role in heat dissipation in three pinniped species
Characteristics | Harbor seal | Northern elephant seal | California sea lion |
|---|---|---|---|
1. Thin epidermis | +, head | +, head | +, head |
2. Epidermis keratinization | + | + | + |
3. Epidermal scale-like ridges | + | + | + |
4. Thick epidermis | - | + | + (vent. abd, tx, flippers) |
5. Smooth muscle in dermis | + | + | + |
6. Dermal veins w/t valves | + | + | + |
7. Primary hair follicles | +, all the body | +, all the body | +, flippers bare ventrally |
8. Dermal elastic fibers | + | + | + |
9. Dermal collagen | +++ | +++ | +++ |
10. Wool hair (secondary hair follicles) | + (head, vent. & dors. abd, vent., lat tx, glut., tail, flipper, neck, head) | - | + (tx, vent & dors. abd, neck, glut, head) |
11. Arrector pili | - | - | - |
12. Sebaceous glands | + | + | + |
13. Sweat glands | + (not prominent) | + (not prominent) | + (prominent) |
14. Brown adipose tissue | - | - | - |
15. Hypodermal vessels | + | + | + |
16. Hypodermal adipose tissue. | +++ | +++ | +++ |