THE ANIMAL FILES

Naked mole-rat

Heterocephalus glaber

Digging teeth sit outside a closed mouth.

Naked mole-rats excavate underground tunnels with their incisors. A colony divides work around a breeding female, and underground plant parts provide food. Their lips close behind the digging teeth, keeping soil out of the mouth.[2]

Follow the evidence ↓
Naked mole-rat
Image: Roman Klementschitz, Wien · Commons · CC BY-SA 3.0
Teeth as excavators
Lips close behind the incisors.[2]
A colony's work
Most members help rather than breed.[2]
Eating underground
Tubers provide important food.[2]

Teeth as excavators

Large incisors break hard soil while closed lips exclude loose dirt. Other workers move excavated material along the tunnel towards a surface opening.[2]

A colony's work

One female breeds, while workers maintain tunnels, find food and care for pups. Workers are physiologically capable of reproduction; their current social role is not permanent anatomical sterility.[2]

Eating underground

Underground plant parts supply food and moisture. Groups may eat inside a large tuber while leaving its outer layer; this may keep the plant growing, rather than guaranteeing every partly eaten tuber regenerates.[2]

A COMMON MIX-UP

Are non-breeding workers permanently sterile?

No. Social suppression differs from lacking reproductive capacity.[2]

TRY A LITTLE REASONING

How can teeth dig without filling the mouth with soil?

Reveal the explanation

The lips seal behind the protruding incisors, separating the digging surface from the mouth opening.[2]

Sources & editorial notes

Original explanations, checked against the sources below. The image has its own credit and licence above.

  1. NCBI Taxonomy — Heterocephalus glaber
  2. Smithsonian National Zoo — Naked mole-rat

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