Slow loris - (NYCTICEBUS COUCANG)
The slow loris is any one of three species of loris classified in the genus
Nycticebus. These slow moving Strepsirhini primates range from Borneo and the
southern Philippines in Southeast Asia, through Bangladesh, Vietnam, Indonesia,
India (North Eastern India, Bengal), southern China (Yunnan area), and Thailand.
They are hunted for their large eyes, which are prized for local traditional
medicine, leaving them on the endangered species list. [3] The Indonesian name,
malu malu, can be translated as "shy one".[4] The Pygmy species is listed as
threatened by the U.S. Fish & Wildlife Service.[5] The International Union for
Conservation of Nature and Natural Resources (IUCN) Red List of Threatened
Species classifies the Javan Slow Loris as an endangered species and all other
species of slow loris as vulnerable.
1 Physical characteristics
Adult slow lorises range in size from 21 to 38 cm, depending on the species, and
weigh up to 2 kilograms. The tail is a mere stump, and the forelimbs and
hindlimbs are of roughly equal length (quadrupedal). The short, thick fur can
have a variety of colours, but most commonly is reddish-grey with white
undertones. They have well developed opposable thumbs, which they use to grasp
and hold branches, and a very flexible back. A specialized arrangement of blood
vessels in the wrists and ankles (rete mirabile) prevents muscle cramps and
allows the slow loris to cling for extremely long periods of time. They have a
grooming claw on one foot. Their eyes are large and point forward and also
upward, and color vision is minimal. Their ears are small and nearly hidden in
the fur. They are generally built stronger than the slender lorises, and possess
a strong sense of smell.
The cranial form of the slow loris follows most of the expectations of the
Strepsirhini/Prosimii suborder. To begin, the braincase is low and ovaloid;
neither the frontal nor the occipital lobe has expanded much. Furthermore, the
frontal suture is visible and the lacrimal bone is located outside of the eye
socket. The slow loris' nocturnal behavior results in relatively large eyes.
Slow lorises have postorbital closure, but lack full orbital closure. The
spatial relationship between the tympanic ring and the bulla of the slow loris
is classified as being attached on the inside. Unlike the majority of other
members of the suborder Prosimii, the slow loris does not have inflated bulla.
Its foramen magnum is located in a more posterior position. Moving towards the
anterior aspect of the cranium, there is a separation between the two most
mesial incisors that corresponds to the moist rhinarium found in Strepsirhinis.
A distinguishing feature between superfamilies Lemuroidea and Lorisoidea is the
loris’ relatively short, pipe-like nose. Finally, as expected, the
splanchnocranium of N. coucang is on the same level as its neurocranium.
As with the cranial form, the dental morphology of the slow loris is consistent
with other Strepsirhines. The mandible is V-shaped and is unfused and the dental
formula reads 2.1.3.3 / 2.1.3.3. Despite having the same number of teeth, the
teeth of the maxilla are arranged quite differently from those of the mandible.
There is a space between the two most mesial incisors and all four incisors are
very small. In the mandible, the incisors and the canines are procumbent. The
canine’s shape resembles an incisor (incisiform). The lateral connection of
these six teeth forms a dental comb. The presence of a dental comb is attributed
to three different forms of use: dietary, social, and defense. As a result of
the canines’ inclusion in the dental comb, P2 shape changes as well and
resembles a canine (caniform). The mandibular condyle of the slow loris is
almost on the same level as the occlusal surface of the teeth, which results in
the posterior teeth occluding before the anterior teeth. The presence of a
glenoid process controls the movement of the mandible. As the slow loris is a
frugivoris primate, the cusps of its teeth are low and rounded, not sharp and
spiky.
The slow-climbing and arboreal quadruped nature of the slow loris shapes its
postcranial anatomy. Moving this way requires a flexible body (lateral flexion
and rotation of the vertebral column) with a sturdy grip. The elongation of the
lumbar vertebrae aids in creating the flexible body of the slow loris In
addition, the scapulas are very laterally located and broad. This helps to
facilitate the climbing N. coucang frequently engages in. Since neither of its
pair of limbs dominates movement, the forelimbs and hind-limbs are approximately
the same length; its intermembral index is very close to 1. Two of the most
distinct features of all slow lorises are the hands and feet. The hands have
broad palms and a pollex capable of 180º adduction from the other digits. Digit
II has become significantly reduced, thereby allowing for a wider and stronger
grasp. The hands lack interdigital webbing between III, IV, and V, which allows
for wide expansion of the digits. The feet are very similar to the hands, except
the hallux is larger than the pollex. On the foot there is one claw; all other
digits contain nails. These grasping capabilities allow for the climbing and
hanging that are characteristic of its movement.
Defense
Slow lorises can produce a toxin which they mix with their saliva to use as
protection against enemies. Mothers will lick this toxin onto their offspring
before leaving them to search for food. The toxin is produced by glands on the
insides of their elbows. The lorises suck it into their mouths and deliver it
when they bite or lick.[6] Loris bites cause a painful swelling, and the toxin
has been found to be fatal. Cases of human death have been due to anaphylactic
shock.[7] If the toxin does not deter a predator, the slow loris will often drop
from the branch to the ground and roll into a protective ball.
Feeding
Slow lorises are opportunistic carnivores, typically eating insects, mollusks,
lizards, small birds, eggs, and other small vertebrates. With their slow, quiet
movements, they creep up on their prey in order to catch it with a quick snatch
using both hands. When meat is unavailable, they will also eat fruits, young
leaves, and gum exudate from trees. Their metabolic rate is 40% slower than
predicted based on size.
Reproduction
Slow lorises are polygamous[8] and breed throughout the year. After an
approximately 190-day gestation period, the female gives birth to one (or rarely
two) young. Lorises are typically limited to one or two litters per year.
However, pygmy slow lorises (Nycticebus pygmaeus) have seasonal breeding habits.
Females come into estrus in February and March, and babies are born in late
summer. Pygmy lorises also have larger litters. At least 50% of litters contain
more than one fetus, and there have been up to four infants documented in one
litter. Newborn lorises clasp to the belly of the mother (or occasionally the
father). Infants are born very well-developed, and mothers will park them on
branches at night while they search for food. Youngsters begin eating solid food
by the time they are about four weeks old and are weaned by six months of age.
Sexual maturity is achieved around 10 to 24 months. The life expectancy of the
slow loris is up to 14 years in the wild and up to 26 years in captivity.