Named by: Rafinesque, 1821
Taxonomy: Synapsida, Sphenacomorpha, Sphenacodontia, Sphenacodontoidea, Therapsida, Theriodontia, Cynodontia, Probainognathia, Mammaliamorpha, Mammaliaformes, Mammalia, Theria, Eutheria, Placentalia, Laurasiatheria, Ferae, Pholidotamorpha, Pholidota, Manidae
Included species: P. tricuspis (type), P. tetradactyla
Pangolins are some of the most peculiar mammals. They are toothless, relying on their long, sticky tongue to capture insect prey. They are also covered in a coat of hard scales that serve as protection from predators. These unusual features may recall similarities with the anteaters and armadillos of South America. However, genetic studies have shown that the closest living relatives of pangolins are the carnivorans, the great radiation of predatory placental mammals including cats, dogs, bears, seals, and more.
Living pangolins are currently split into three different genera, of which the smallest are members of the genus Phataginus. Weighing around 2 kg (4.4 lb) as adults, Phataginus live in the forests of central Africa. Like other pangolins, they can roll into an armored ball to protect themselves from attack, but their scales are generally thinner and flimsier than those of larger pangolins. This, combined with their small size, likely makes them more vulnerable to predation, and they may rely more on their repulsive anal secretions to deter large carnivores.
P. tricuspis is the better-studied of the two species of Phataginus. Members of this species can retract their eyes into their sockets (an ability apparently shared by at least some other pangolin species). They regularly forage in trees and are able to climb quickly using a “caterpillar-like” motion. To get down from trees, they spiral around the tree trunk while supporting themselves using their tail. They have also been observed performing more expeditious descents by rolling into a ball before dropping directly to the ground.
Despite being at home in the trees, however, P. tricuspis spend much of their time on the ground, perhaps due to the greater availability of their preferred prey on the forest floor. While feeding, they flick their scales continuously to shake off attacking soldier ants and termites, and sweep their tail from side to side to herd their prey within reach. After feeding, they groom themselves meticulously using their hind feet to uncover any insects that may have ventured underneath their scales. During the day, P. tricuspis rest in tree cavities or in shallow burrows. They breed throughout the year; one field study rarely found females that were not pregnant.
Pangolins are typically solitary, but P. tricuspis exhibit behaviors suggestive of greater sociality in this species. Pairs have been found using the same tree hollows, and in captivity groups of up to six individuals have been observed sharing sleeping quarters and following one another around in single file. Juveniles in particular appear eager to seek contact with other pangolins and even their human handlers. One individual regularly returned to visit its handlers over a period of six months after being released into the wild. In general, P. tricuspis seem like a friendly bunch. However, males are known to fight to the death by slashing each other with their front claws. P. tricuspis have poor eyesight, so their social contacts are established using scent. They are also quite sensitive to vibrations, including sound.
Though most pangolins are competent climbers, members of the other species of Phataginus, P. tetradactyla, are particularly specialized for arboreal life. Their incredibly long, prehensile tail contains up to 47 vertebrae, more than that of any other mammal. The tail is strong enough to support their entire body weight for long periods, allowing them to hang by their tail. P. tetradactyla almost never descend to the ground. They rest in tree hollows or hollowed-out insect nests. Cavity-nesting birds are reportedly known to mob them, perhaps seeing them as competition for tree hollows.
P. tetradactyla are said to be more diurnal than P. tricuspis, which may reduce competition between the two species. It is likely that the highly arboreal habits of P. tetradactyla, along with their preference for forests that experience regular flooding, correspond to a specialization in feeding on ants and termites that avoid floods by nesting high in the forest canopy. Such insects tend to have well-developed chemical weaponry, so it is plausible that P. tetradactyla possesses adaptive countermeasures to these defenses. However, due to the lack of detailed study, such specializations, if present, remain unknown.
Reference
- Kingdon, J. and M. Hoffmann (eds.). 2013. Mammals of Africa Volume V: Carnivores, Pangolins, Equids and Rhinoceroses. A&C Black Publishers Ltd., London. 560 pp.
—Albertonykus
Synapsid Notebook 