SKIN/COAT/PELAGE - Editorial Comment

Adult: 

• Adult elephants are only sparsely haired. As well as the obvious hairs on the tail, hair is present mainly on the forehead, chin and lips, eyelids (eyelashes), knees, around the external ear canal and around the vulva.
• The skin is usually described as dark grey or brown to grey-black. 
• There is a panniculus carnosus allowing the elephant to move the skin, but no erector pili muscles to pull the hairs erect.
• Elephants have mammary glands (a single pair, found just behind the front legs in females) and the unique temporal glands; secretion from this gland may be copious in males in musth.
• The presence of sebaceous glands and sweat glands has been debated; the presence of sweat underneath harness and a slight secretion over the nails has been reported. Sebaceous glands were detected during dissection of a fetus and a detailed study of the interdigital skin of two elephants detected eccrine type sweat glands but no apocrine glands.

Adult colour variations:  

• In the Asian elephant, nonpigmented areas over the forehead, ears, trunk base and chest are not uncommon. 
• The true skin colour of elephants is often hidden by the colour that the local soil places on the body.

Newborn/Juvenile:  

• Elephant calves, particularly newborn calves, have much more hair than do adults. This hair may be yellowish or reddish brown. It becomes less obvious as the animal grows.

(References are available in detailed literature reports below)

Hair / Moult

• Elephants are only sparsely haired. (B147)
• Hair in elephants is found mainly on the forehead, lips (upper and lower), ear orifices, the back and the end of the tail. (B10.49.w21)
• Hairs are stiff and bristly. (B147)
• The end of the tail bears a tuft of hair. (B147)
• There are sensory hairs on the trunk. (B384.3.w3)
• Elephants have sparse, bristly hairs over the body. (B451.1.w1) 
• Elephants have long eyelashes, hairs, probably protective, in the ear orifices, and long hairs on the lower lip. (B451.1.w1)
• Hairs are stiff and bristly and are firmly rooted. They are found more abundantly on the forehead, lower lip, upper lip, the ear orifices and the tail tip. Those on the tail are particularly long and stiff. (B212.w6)
• Adults have hairs on the chin, eyelids, trunk, knees and tail, as well as around the vulva and the external auditory meatus. (B450.17.w17)

• Newborn calves have a coat of brown hairs, widely spaced, giving a halo effect around the body; the hair becomes less obvious as the animal grows. (B147)
• Younger animals are more prominently haired than are older animals. (B10.49.w21)
• At birth the calf is covered with hair which is yellowish or reddish-brown. (B384.3.w3)
• In utero there is a felt of long, downy hair, the laguno, over the calf; this is mainly shed before the calf is born, however the calf still is relatively hairy, especially on the head and back. (B451.1.w1)
• In calves usually more hair is present than in adults. (B212.w6)
• Newborn calves are covered with longish hair. (B212.w11)
• There is much more hair on the fetal and newborn elephant than on the adult. (B450.17.w17)

Dermis, Subdermis and Epidermis

• The skin on the ears is only several millimetres thick, but on the body it is 1.9 to 3.2 cm thick, being thinnest over the forelimbs and shoulders and thickest over the hindquarters and hind limbs. (B10.49.w21)
• The skin is usually grey-black in colour. (B10.49.w21)
• In the healthy elephant the skin has a uniform temperature, is pliable, and there is little surface dead skin and scurf. (B10.49.w21)
• The skin is dark grey to brown in colour; often there is an area of the forehead, ears, trunk base and chest which is flesh-coloured. (B147)
• Dark gray to brown; may be marked with flesh-coloured areas on the forehead, ears and chest. (B285.w3)
• The true colour of the skin is often hidden under the colour of the soil of the area in which the elephant lives, due to the habits of mud wallowing and throwing soil over the back. (B147)
• Elephants lack erector pili muscles. (B384.3.w3)
• The skin is kept flexible by diffusion of water from the body through the skin; this is then lost by evaporation. Losses may be about 2.5 L per hour for a juvenile of 1.2 tonnes, or twice that amount for an adult bull elephant. (B384.4.w4)
• The skin is very thick over the back and sides (up to 2.0 - 3.0 cm), while the skin on the abdomen is much thinner. (B451.1.w1)
• The skin is marked by ridges and creases; these are prominent on the forehead and trunk, where warty outgrowths are found. (B451.1.w1)
• The skin feels dry, soft and supple. (B451.1.w1)
• Sweat glands have not been found histologically, but considerable water vapour is lost through the skin, with sweat being found under the harness of working Asian elephants. (B451.1.w1)
• The skin is greyish black, but generally appears the colour of the local soil. (B451.1.w1)
• Over the ears and trunk of the Asian elephant there may be pinkish, unpigmented areas.  (B451.1.w1)
• The skin is thick; its thickness varies over the body. (B212.w6)
  • Due to the skin thickness, abscesses do not easily come to a "head" and burst. (B212.w6)
• The skin is loosely attached to the underlying tissue and may be moved at will using the subcutaneous muscle layer, the  panniculus carnosus. (B212.w6)
• The skin is greyish black; often the true colour is hidden under the colour of the soil or mud placed on it. (B212.w6)
• Despite being thick, the skin is very sensitive. (B212.w6)
• In the healthy elephant the skin is pliable, evenly warm and free of scurf. (B212.w6)
• The skin is dark brown to grey, varying over the body. (B450.17.w17)
• The epidermis is attached to the dermis by hexagonal "studs", large papillae with their surface covered with smaller papillae. (B450.17.w17)
• The skin is as thick as 3.2 cm over the body dorsally, 2.5 - 3.5 cm over the lateral aspects of the body and limbs, 1.8 mm over the medial side of the ear and 1.0 cm on the medial side of the legs. (B450.17.w17)

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Glandular Structures

• Sweat glands are present throughout the skin, and mainly sparse, except for just proximal to the toenails; a slight secretion may be visible here. (B10.49.w21)
• Elephants lack sebaceous glands associated with their hair follicles. (B147)
• Elephants lack both sebaceous glands and sweat glands. (B384.3.w3)
• There are small sweat glands as seen by the secretion through the skin, most visible when pack-gear is removed from the elephant. (B212.w6)
• The presence of sweat has been reported on elephants. Sebaceous glands but not sweat (sudoriferous) glands were found in an Asian elephant fetus by one researcher. Neither were detected in the dissection of an adult elephant by other workers. Some researchers have argued that there is no evidence of the presence of sweat glands, and that they are not required by elephants. (B450.17.w17)
• Sebaceous glands have been reported in elephants. (B455.w4)
• Moisture is often seen between the toes and along the nail cuticle on hot days. Histological examination of haematoxylin and eosin stained sections of the interdigital skin of two Asian elephants sporadically detected interdigital glands, deep in the reticular dermis, resembling eccrine glands of humans. With H&E the glands were seen to be composed of lobules of secretory glandular units, ducts, and fibroconnective tissue. Using Periodic acid-Schiff, it could be seen that the secretory units consisted of clear cells resting on a basement membrane, and surrounded by myoepithelial cells. Scattered dark cells were visible basally located, containing a granular distribution of neutral polysaccharide. The ducts were lined by a double row of cuboidal epithelial cells having eosinophilic, somewhat granular, cytoplasm. The secretions were positive for Alcian blue at pH 2.5 but not at pH 5.0, indicating nonsulphated acid mucopolysaccharides. Immunohistochemical staining using monoclonal antibodies revealed positive reactivity to cytokeratin 8 (ductal and secretory epithelial cells) and cytokeratin 10 (ductal cells). (J21.71.w1)

Temporal glands:

• Elephants possess unique glands, the temporal glands, under the skin  between the eye and the ear canal on either side of the head. There is a single duct from each gland onto the surface of the skin. (B10.49.w21)
  • Males show secretion from the temporal glands during musth. (B10.49.w21, B384.8.w8)
  • Female Asian elephants show secretions rarely and in insignificant quantities. (B10.49.w21)
    • Females Asian elephants may show temporal gland secretion while on heat or when giving birth, but rarely otherwise. (B384.8.w8)
• The temporal glands are found one on each side of the head, between the ear and the eye. They can be quite large, weighing up to 1.5 kg in males. They produce a copious secretion which smells strongly of elephant and runs down the side of the face. (B451.1.w1)
• The temporal glands are found midway between the ear orifice and the eye, one on either side of the head, with a duct opening onto the skin here. They are inactive most of the time. (B212.w12)
• Elephants have temporal glands. (B450.17.w17)

Mammary glands:

• There is a single pair of nipples, just behind the front legs. (B147)
• There are two mammary glands, situated just behind the front legs. These become greatly enlarged in the latter part of pregnancy and milk is secreted from shortly before parturition. (B212.w11)

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