MorphologyRead full entry
Grey slender lorises have grey or reddish dorsal pelage with a darker medial stripe and a white ventrum. Their distinctly forward facing eyes are large and set closely together, while the rostrum is small and pointed. The coloring of the face is also distinctive; they have circumocular patches, darker preauricular hair, and a white rim between the circumocular patch and preauricular hair. Grey slender lorises have no tails and the limbs are long and extremely slim. Male weight ranges from 180 to 290 grams, depending on the subspecies. Female weight ranges from 180 to 275 grams. The average male length is 24.1 cm and the average female length is 23.4 cm.
There are four subspecies: Loris lydekkerianus lydekkerianus, L. l. grandis, L. l. malabaricus, and L. l. nordicus. These different subspecies differ in geographic location, pelage, and size.
Loris l. lydekkerianus has gray body color, a narrow circumocular patch, and a broad white rim between the dark preauricular hair and circumocular patch. The subspecies is generally larger in mass, with males weighing approximately 260 grams and females weighing 275 grams. The head length, body length, and head breadth are larger in L. l. lydekkerianus than in L. l. malabaricus.
Loris l. malabaricus has a reddish body color, a broad circumocular patch, and a narrow white rim between the dark preauricular hair and circumocular patch. Both male and female adults weigh approximately 180 grams.
Loris lydekkerianus has many distinctive derived characteristics including extremely slender limbs, the closest orbital approximation of all primates, small hands in comparison with the feet, feet with shortened second digits, a unique non-saltatory locomotor style, digestive specializations for ingesting toxic prey, and an unusually low basal metabolic rate. The species also exhibits retia mirabilia of the proximal limb vessels, an adaptation that allows for extended periods of arboreal clinging.
Grey slender loris appearance changes significantly throughout its development. Infants (4 to 8 weeks) have fluffy, large heads relative to body size. Juveniles (2 to 3 months) have particularly fluffy pelage all over the body, and adults (4 months onward) exhibit full body size and complete adult coloration patterns. External genitalia is also present in adults, with estrous females displaying enlarged genitalia, and male testes alternating between descended and inguinal stages every other night. In Loris lydekkerianus, no pattern has been observed with respect to male testes state and sexual activity. However, in the closely related slender loris (Loris tardigradus), enlargement of male genitals appears to be affected primarily by ambient temperature, with testes enlargement occurring during periods of increased temperature. Lastly, Loris lydekkerianus females have two sets of nipples, a feature that proves useful when females give birth to twins.
Range mass: 180 to 290 g.
Average length: Females: 23.4; Males: 24.1 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger