Anatomy

Chinese pangolins are scaled, endothermic mammals similar in appearance to anteaters or armadillos. Their bodies are almost entirely covered in hard, overlapping keratinous scales - though their limbs have softer, non-overlapping scales that allow them greater mobility. They walk as quadrupeds, on all fours, with a swaying motion of their head and neck to account for their stiffer, heavily-armored body (their head swings to the side opposite of the front limb stepping forward).

The pangolin vertebral column has a total of 32 to 33 vertebrae: 7 cervical, 16 thoracic, 4 sacral, and between 5 and 6 lumbar vertebrae have been noted in scientific observations.

Pangolins can be both ground-dwelling and tree-climbing animals. They use their sharp claws to climb trees but also to dig burrows and destroy ant and termite mounds in search of food. Their long, sticky tongue come in handy after mound destruction to catch insects.

Physiology

Integumentary System (Skin/Scales)

The scales of a pangolin are made of keratin, the same protein that comprises human fingernails. Their scales act as a defense mechanism to predators - pangolins can curl into a tight ball when threatened, protecting vulnerable internal organs inside of their scales.
Scales of infant pangolins are present at birth, though are much softer in composition; they tend to harden after approximately the second day of life.

Digestive System (Tongue)

Pangolins are toothless, so they rely only on their tongue to pick up insects. The sticky tongue of a pangolin helps it to grab ants and termites from inside of mounds. The different papillae (raised bumps) are responsible for both mechanical digestion and tasting functions.

Digestive System (Stomach)

The stomach of a pangolin is used to digest the insects a pangolin captures with its tongue. It is c-shaped and covered with a mucosal layer made of overlapping spiral folds. Upon dissection, scientists have found exoskeletons of insects, straw, roots, and small stones in the pangolin's stomach contents.

Muscular System (Muscles)

The skeletal muscle tissue of a pangolin is uniquely developed for their mobility on the ground and climbing trees. The shoulder girdle muscles have adapted in a way that armadillo muscles have not - their shoulder muscles fully cover their scapula and, in some instances, cross the shoulder and attach to the humerus arm bone. This muscle design is an evolutionary modification that allows them to both dig and climb trees. The anatomical structure of these muscles also suggests that it walks with a swaying head motion, to compensate for its larger, rigid body structure.

References:

Gong, S., Hua, L., Wang, F., Li, W., Ge, Y., Li, X., & Hou, F. (2015). Captive breeding of pangolins: Current status, problems and future prospects. ZooKeys, 507, 99–114. https://doi.org/10.3897/zookeys.507.6970

Kawashima, T., Thorington, R. W., Bohaska, P. W., Chen, Y.-J., & Sato, F. (2015). Anatomy of shoulder girdle muscle modifications and walking adaptation in the scaly chinese pangolin (manis pentadactyla pentadactyla: Pholidota) compared with the partially osteoderm-clad armadillos (Dasypodidae). The Anatomical Record, 298(7), 1217–1236. https://doi.org/10.1002/ar.23170

Lin, M. F., Chang, C.-Y., Yang, C. W., & Dierenfeld, E. S. (2015). Aspects of digestive anatomy, feed intake and digestion in the Chinese pangolin (manis pentadactyla) at Taipei Zoo. Zoo Biology, 34(3), 262–270. https://doi.org/10.1002/zoo.21212

Min, Y., Wu, S., Zhang, F., & Xu, N. (2020). The stomach morphology and contents of the Chinese Pangolin (Manis Pentadactyla). Journal of Zoo Biology, 3(1), 13–20. https://doi.org/10.33687/zoobiol.003.01.2874

National Geographic. (n.d.). Pangolins. Animals. Retrieved from https://www.nationalgeographic.com/animals/mammals/facts/pangolins

Prapong T, Liumsiricharoen M, Chungsamarnyart N, Chantakru S, Yatbantoong N, Sujit K, Patumrattanathan P, Pongket P, Duang-ngen A, Suprasert A. 2009. Macroscopic and microscopic anatomy of pangolin's tongue (Manis javanica). Kasetsart Veterinarians 19:9–19.

Sun, N. C.-M., Pei, K. J.-C., & Wu, L.-Y. (2021). Long term monitoring of the reproductive behavior of Wild Chinese Pangolin (Manis Pentadactyla). Scientific Reports, 11(1). https://doi.org/10.1038/s41598-021-97618-4

Wikimedia Foundation. (2022, August 5). Pangolin. Wikipedia. Retrieved from https://en.wikipedia.org/wiki/Pangolin

Keywords: endothermic; vertebral column; skeletal muscle tissue; gestation period; placenta