A new type of toothless rat that feasts on earthworms

Newly discovered 'toothless' rat Paucidentomys vermidax Credit: PA Wire

A new species of rat has been discovered that cannot gnaw or chew. It looks a bit like a shrew and is called Paucidentomys vermidax.

It has fang-like upper incisors which are useless for gnawing and no back teeth. It survives exclusively on earthworms.

The creature was found in remote rainforest on the Indonesian island of Sulawesi.

It shares some characteristics with insectivorous shrew rats from the Philippines but has taken an evolutionary step further by completely dispensing with chewing molars.

There are more than 2,200 rodent species in the world and until this discovery all had molars in the back of their mouth and incisors at the front. This is an example of how species, when faced with a new ecological opportunity, in this case an abundance of earthworms, can evolve the loss of traits that were wildly successful in previous circumstances.

The discovery represents a new step in rodent evolution Credit: PA Wire
  • The creature has a rat-like tail but a long, thin nose similar to a shrew's

  • Its only teeth are its incisors, which in the upper jaw end in twin points

  • The Latin derived genus name Paucidentomys means "few-toothed mouse" and the species name vermidax means "devourer of worms"

The specialised incisors of rodents give them the distinct ability to gnaw - a defining characteristic of rodents worldwide. In having lost all teeth except a pair of unusually shaped incisors that are incapable of gnawing, this new rat is unique among rodents.