Earth's smallest mammals alive today

American shrew mole Neurotrichus gibbsii, the American shrew mole, is the world's smallest species of mole. The Gibb's shrew mole has a body length of 69-84mm and a tail length of 31-42mm.

Tasmanian pygmy possum This species, also known as the tiny pygmy possum or Cercartetus lepidus, is the world's smallest possum. The typical length of the head and body is 70mm, while the prehensile tail is 64mm.

Paucident planigale Planigale gilesi is one of five planigale species, which are tiny carnivorous marsupials. It has a head and body length of 60 to 80mm, and a tail length of 55 to 70mm.

Narrow-nosed planigale Planigale tenuirostris, though it measures only up to 7.5cm, is a vicious predator. It takes down insects and small lizards, occasionally even ones bigger than itself.

Long-tailed planigale Planigale ingrami is the last planigale on this list, and is the world's smallest marsupial. Its head and body are only 55-65mm long. Females of the species weigh on average 4.3g, whereas males weigh an average of 4.2g.

Baluchistan pygmy jerboa Salpingotulus michaelis, or the dwarf three-toed jerboa, has a body around 4.4cm long, and a tail of 8cm. On average, adult females weigh 3.75g.

African pygmy mouse The African pygmy mouse, Mus minutoides, holds the joint title for the world's smallest rodent with the Baluchistan pygmy jerboa.

Kitti's hog-nosed bat By body size, Kitti's hog-nosed bat is the smallest mammal on Earth, at 29-33mm long. It also has the smallest skull of any mammal. It's not quite the smallest by body weight, though, with the smallest individuals weighing around 1.7g.

Etruscan shrew Also known as the white-toothed pygmy shrew or Suncus etruscus, the Etruscan shrew is the smallest mammal by weight alive today. At 36–52mm long, excluding tail, it's larger than Kitti's hog-nosed bat.

Batodonoides vanhouteni (extinct) At only 1.3g, the extinct B. vanhouteni is believed to be the smallest mammal that ever lived. This tiny, shrew-like animal roamed North America 53 million years ago.