Integument in Antarctic seals: A comparative study and its relation to extreme environments

Due to the semi-aquatic lifestyle of seals and the extreme climates they inhabit, their integumentary system has aroused the curiosity of several authors for more than a century. The aim of this contribution was to perform an exhaustive histological description of the integument Antarctic seals through different methodological approaches in a comparative framework. The species considered include the ice-obligate—Weddell (Leptonychotes weddellii) and leopard (Hydrurga leptonyx) seal—and the ice-tolerant, and southern elephant seal (Mirounga leonina). In addition, we attempted to link the histological features to their different lifestyles. All three species showed features related to their amphibious lifestyle (i.e., parakeratotic epidermis with abundant melanin granules, dermis with numerous arteriovenous anastomoses and a great amount of elastic fibres). In aquatic mammals, parakeratosis would decrease cellular replacement, the great amount of melanin is related to the high exposure to solar radiation, the presence of arteriovenous anastomoses is related to thermoregulatory mechanisms, and the presence of elastic fibres is due to variations of thickness in the adipose tissue that requires high elasticity of the dermis.