Sci&Tech Writer Madison Harding-White reviews a small and unusual member of the sloth genus

A Neuroscience graduate interested psychology, debate and sustainable lifestyles.

Whilst many will be familiar with the now popular three-toed sloth, few are aware of the separate and much smaller species Bradypus pygmaeus – otherwise known as the pygmy sloth. Recognised as a distinct species in 2001, this sloth is found only on the Isla Escudo de Veraguas, an island off the coast on Panama.

Reflecting their name, pygmy sloths measure between just 19-21 inches long in adulthood (compared to the approximate 31 inches of a brown-throated sloth) making them a dwarf species within the genus. The reduced size of these sloths is thought to be due to island dwarfism: a process in which the reduction in habitat size and resources as well as predator changes causes a small body size to be more advantageous to survival.

The reduced size of these sloths is thought to be due to island dwarfism… the reduction in habitat size and resources

In all other ways, the pygmy sloth looks much like the well-loved brown-throated and three-toed varieties with light brown fur, three claws on each appendage and distinctive dark eye markings. Their externally set ear canals are however conspicuously large- another feature thought to be characteristic of their rapid, isolated evolution.

Despite their habitat being restricted to just a small patch of land, the pygmy sloth is currently critically endangered- with only 48 estimated to still be alive in the wild. Their endangerment is largely due to deforestation which destroys both their habitat and mangrove leaf food source but also poaching, as external visitors have been known to kill and capture sloths for display.

Whilst the pygmy sloth is critically endangered, it is not listed as an endangered animal under the US Endangered Species Act, meaning numbers are at risk of further decline.