Adaptations of the Mammalian Skin to the Aquatic Mode of Life

Sokolov, W.

doi:10.1038/195464a0

Cited by 36 publications

(27 citation statements)

References 1 publication

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“…Our findings correspond with results of the body epidermis in the harbor porpoise and in delphinids (Tursiops truncatus, Delphinus delphis and Orcinus orca; Sokolov et al, 1973;Harrison and Thurley, 1974). Ultrastructural studies of the epidermis in various odontocetes and mysticetes confirm that the incomplete cutaneous keratinization is probably a consistent feature in all cetaceans (Sokolov, 1960(Sokolov, , 1962Sokolov and Kalashnikova, 1971;Evans and Maderson, 1973;Haldiman et al, 1985;Knospe, 1989). Our TEM studies reveal large and numerous lipid inclusions with few tonofilaments and the absence of keratohyalin granules, so there seems to be a lack of matrix protein.…”

Section: Discussion Epithelial Lining Of the Epicranial Air Spacessupporting

confidence: 72%

Histological and ultrastructural aspects of the nasal complex in the harbour porpoise, Phocoena phocoena

Prahl

Huggenberger

Schliemann

2009

Journal of Morphology

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During the evolution of odontocetes, the nasal complex was modified into a complicated system of passages and diverticulae. It is generally accepted that these are essential structures for nasal sound production. However, the mechanism of sound generation and the functional significance of the epicranial nasal complex are not fully understood. We have studied the epicranial structures of harbor porpoises (Phocoena phocoena) using light and electron microscopy with special consideration of the nasal diverticulae, the phonic lips and dorsal bursae, the proposed center of nasal sound generation. The lining of the epicranial respiratory tract with associated diverticulae is consistently composed of a stratified squamous epithelium with incomplete keratinization and irregular pigmentation. It consists of a stratum basale and a stratum spinosum that transforms apically into a stratum externum. The epithelium of the phonic lips comprises 70-80 layers of extremely flattened cells, i.e., four times more layers than in the remaining epicranial air spaces. This alignment and the increased number of desmosomes surrounding each cell indicate a conspicuous rigid quality of the epithelium. The area surrounding the phonic lips and adjacent fat bodies exhibits a high density of mechanoreceptors, possibly perceiving pressure differentials and vibrations. Mechanoreceptors with few layers and with perineural capsules directly subepithelial of the phonic lips can be distinguished from larger, multi-layered mechanoreceptors without perineural capsules in the periphery of the dorsal bursae. A blade-like elastin body at the caudal wall of the epicranial respiratory tract may act as antagonist of the musculature that moves the blowhole ligament. Bursal cartilages exist in the developmental stages from fetus through juvenile and could not be verified in adults. These histological results support the hypothesis of nasal sound generation for the harbor porpoise and display specific adaptations of the echolocating system in this species.

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Section: Discussion Epithelial Lining Of the Epicranial Air Spacessupporting

confidence: 72%

Histological and ultrastructural aspects of the nasal complex in the harbour porpoise, Phocoena phocoena

Prahl

Huggenberger

Schliemann

2009

Journal of Morphology

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“…Total drag would therefore be reduced due to the dampening of beginning turbulence, thereby extending laminar flow. Also, dampening may be enhanced by actively adjusting the flexibility and movement of the skin (Sokolov, 1962;Lang, 1966). Although this scheme seems possible, turbulence reduction by dolphin skin has never actually been demonstrated.…”

Section: Skinmentioning

confidence: 99%

Dolphin swimming–a review

Fish

Hui²

1991

Mammal Review

222

154

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Research into dolphin swimming has historically been guided by false assumptions of ‘effortless’, ‘high‐speed’ swimming. These assumptions have instigated the development of drag‐reduction hypotheses but tests of these hypotheses have generally had little success. The autecological approach has dominated recent efforts and has been more successful. In this review we summarize results of decades of research efforts to study these creatures. (1) Drag is minimized primarily by the streamlined shape of the body and appendages, with no known contributions from compliant dampening, dermal ridges, secretions, boundary layer heating, or skin folds. All indications are that the boundary layer is turbulent. (2) Muscles for the upstroke and downstroke of swimming dolphins provide approximately equal power. (3) Output force is enhanced by insertions occurring on the long processes of the vertebrae and on the subdermal connective tissue sheath. (4) Measured swimming speeds are lower than previously believed, with maximum reported routine speeds being approximately 3 m/s. (5) Porpoising behaviour appears to be the most energetically conservative manner in which to breathe when swimming at high speed. (6) Riding surf and wind waves involves the balance between the wave slope and the weight of the animal whereas riding the bow wave involves the interaction of the pressure wave in front of a ship and the drag of the dolphin.

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“…For the body region in contact with the ground, heat transfer is limited to this conductive process (Hind and Gurney, 1998;Ohata and Whittow, 1974). A proportion of the heat reaching body surfaces not in contact with the ground may be bound in the water or air trapped within the seal's pelage, which thus may provide an isolating layer at least when the seal is dry (Sokolov, 1962;Tregear, 1965). The heat transferred to the medium next to the body can be swept away in a forced convection process with water or air passing by the seal's body surface.…”

Section: Introductionmentioning

confidence: 99%

Thermal windows on the trunk of hauled-out seals: hot spots for thermoregulatory evaporation?

Mauck

Bilgmann

Jones

et al. 2003

Journal of Experimental Biology

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SUMMARY Seals have adapted to the high heat transfer coefficient in the aquatic environment by effective thermal insulation of the body core. While swimming and diving, excess metabolic heat is supposed to be dissipated mainly over the sparsely insulated body appendages, whereas the location of main heat sinks in hauled-out seals remains unclear. Here, we demonstrate thermal windows on the trunk of harbour seals, harp seals and a grey seal examined under various ambient temperatures using infrared thermography. Thermograms were analysed for location, size and development of thermal windows. Thermal windows were observed in all experimental sessions, shared some common characteristics in all seals and tended to reappear in similar body sites of individual seals. Nevertheless, the observed variations in order and location of appearance,number, size and shape of thermal windows would imply no special anatomical site for this avenue of heat loss. Based on our findings, we suggest that, in hauled-out seals, heat may be transported by blood flow to a small area of the wet body surface where the elevation of temperature facilitates evaporation of water trapped within the seals' pelages due to increased saturation vapour pressure. The comparatively large latent heat necessary for evaporation creates a temporary hot spot for heat dissipation.

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Adaptations of the Mammalian Skin to the Aquatic Mode of Life

Cited by 36 publications

References 1 publication

Histological and ultrastructural aspects of the nasal complex in the harbour porpoise, Phocoena phocoena

Histological and ultrastructural aspects of the nasal complex in the harbour porpoise, Phocoena phocoena

Dolphin swimming–a review

Thermal windows on the trunk of hauled-out seals: hot spots for thermoregulatory evaporation?

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