Musculature of the head and neck in naked mole‐rats (Heterocephalus glaber)

Abstract

Naked mole‐rats (Heterocephalus glaber) are eusocial, subterranean rodents from the family Bathyergidae. Their unusual anatomical and physiological traits, including a number of adaptations to their fossorial and eusocial niche, have been relatively under‐studied compared to other rodent species. They have large incisors that are used for social interactions (as well as defense); for navigation and object manipulation; for feeding; and for digging complex tunnel systems. In addition, naked mole‐rats have unusual oral folds that close caudal to their incisors, preventing dirt from entering their oral cavity while digging. They are functionally blind and have reduced pinnae. However, their well‐developed tactile system ‐ relying on their incisors as well as tactile hairs covering the entire body ‐ compensates for their reduced visual and auditory systems.Naked mole‐rat head and neck musculature might also be expected to have adapted to a subterranean niche and present with neotenic features. However, few studies to date have characterized naked mole‐rat musculature. To address this, we performed detailed anatomical dissections on adult naked mole‐rats in order to investigate the presence and attachment sites of the head and neck musculature. We found adaptations to a subterranean niche. For example, musculature associated with ear and eye movements was reduced. Overall, our findings provide insight into head and neck musculature as they relate to ecological and evolutionary adaptations, which can be placed within a comparative anatomical context based on what is present in other species.