A male pale-throated three-toed sloth resting on a branch, one of the living sloth species

Are There Six or Seven Sloth Species? A Family Tree in Motion

Summary: Many guides list six living sloth species, while specialist sources now recognise seven. The difference comes from new research splitting the maned sloth into northern and southern species.

Ask how many sloth species exist and you may get two perfectly confident answers. Plenty of trusted wildlife pages say six. The specialist group that tracks sloth taxonomy now lists seven.

This is not a case of somebody discovering an entirely new sloth hiding in an unexplored forest. The extra name appeared because scientists took a closer look at the maned sloth of Brazil's Atlantic Forest and concluded that northern and southern populations should be recognised as separate species.

Taxonomy, the science of naming and classifying life, can feel like a tidy list carved in stone. In reality, it changes as researchers collect better genetic, anatomical and geographical evidence. Sloths are a lovely example of that family tree still being refined.

First, sloths belong to two very different families

Living sloths are usually introduced as two-toed and three-toed. The names refer to the claws on the front limbs. Both groups have three claws on their hind limbs, so the labels are useful but slightly misleading.

The two groups are not simply close cousins with different feet. They belong to different biological families and followed separate evolutionary paths before arriving at a remarkably similar upside-down canopy lifestyle.

The WWF sloth guide describes two species of two-toed sloth and four species of three-toed sloth, making the familiar total of six. The two-toed species are Hoffmann's and Linnaeus's sloths. The traditional three-toed list contains the pygmy, maned, pale-throated and brown-throated sloths.

Why some current lists now say seven

The Sloth Conservation Foundation now describes seven living species. Its updated account separates the maned sloths into the northern maned sloth, Bradypus torquatus, and the southern maned sloth, Bradypus crinitus.

These animals live in Brazil's Atlantic Forest. Research comparing their skulls, fur and genetic evidence supported recognising the southern population as a separate species. So an older guide that says six is not necessarily careless. It may be using the classification accepted when it was written, before the split was widely adopted.

That makes the modern list two species of two-toed sloth and five species of three-toed sloth. The total is seven, although websites, books and conservation databases do not always update at exactly the same speed.

Meet the two two-toed sloths

Hoffmann's two-toed sloth, Choloepus hoffmanni, occurs across parts of Central and South America. Linnaeus's two-toed sloth, Choloepus didactylus, lives mainly in northern South America.

Two-toed sloths are generally larger than three-toed sloths and have a more varied natural diet. The Smithsonian National Zoo describes Linnaeus's two-toed sloths as canopy mammals with coarse fur, long limbs and large curved claws. They spend most of their lives hanging, feeding and resting among rainforest branches.

Despite the shared nickname, two-toed and three-toed sloths are easy to distinguish when the forelimbs are visible. The face helps too. Three-toed sloths often have a rounder head and dark eye markings, while two-toed sloths tend to have a longer, more prominent snout.

Meet the five three-toed sloths

The brown-throated sloth, Bradypus variegatus, is the species many people picture first. It has a broad range through Central and South America and appears frequently in wildlife photography.

The pale-throated sloth, Bradypus tridactylus, lives in northern South America. Its lighter throat helps distinguish it from its brown-throated relative, although identifying a wild sloth should never rely on one photograph alone.

The pygmy three-toed sloth, Bradypus pygmaeus, is found only on Isla Escudo de Veraguas off Panama. Its tiny range makes it especially vulnerable to habitat damage and disturbance.

Finally come the two maned sloths: the northern maned sloth, Bradypus torquatus, and the southern maned sloth, Bradypus crinitus. Both are associated with Brazil's Atlantic Forest and named for the dark, shaggy mane that is particularly noticeable in adult males.

Why a name change matters outside a science paper

Recognising two species can change how conservationists ask questions. A population once treated as the southern part of one widespread species may turn out to be a distinct animal with a smaller range, different threats and fewer protected habitats than the old map suggested.

Species names also shape surveys, legal protection, funding and recovery plans. If researchers combine two different animals under one label, a decline in one region can be hidden by healthier numbers elsewhere. Separating them can reveal where protection is most urgent.

The reverse caution matters too. A taxonomic split does not automatically tell us how many animals remain or guarantee stronger protection. It is a starting point for better fieldwork, not the end of the conservation job.

Why different answers can both be understandable

The International Fund for Animal Welfare still presents the familiar six-species list, while the Sloth Conservation Foundation presents seven. For a reader, the fairest answer is therefore: many established sources list six, but current specialist taxonomy recognises seven after splitting the maned sloth.

That small disagreement is a useful reminder that wildlife knowledge is alive. Scientists revisit museum specimens, compare populations, sequence DNA and test old assumptions. The result is not needless renaming. It is a sharper picture of the animals sharing the planet with us.

Whether a guide says six or seven, the conservation message remains steady. Every living sloth depends on healthy tropical forest, and some occupy remarkably restricted ranges. Better names help us see those differences clearly, but protecting connected habitat is what gives each branch of the sloth family tree a future.

Sources and image credit

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