brown rat

Consider the infamous brown rats of New York City, which have evolved longer noses and shorter upper molar tooth rows, the better to enjoy the Big Apple's colder weather and higher-quality food.

According to the RSPCA, there are only two species of rats living in the UK - brown rats and black rats.

Although most historical accounts date the arrival of brown rats to about 1775, new evidence suggests this ratty rivalry began much earlier.

Today, both types of rats exist in North American cities, though brown rats are more prevalent.

The past decade has seen a boom in descriptions of unexpected pollinators, including lizards, opossums, brown rats and cockroaches.