Color Blindness in Lemurs

Lemurs are a group of small primates found only on the small island of Madagascar. Due to Madagascar’s highly variable climate lemur evolution has produced a wide range of species, remarkable for such a small geographic area. Lemurs are considered to be the most endangered group of mammals on Earth.

There are over 108 species and subspecies of lemur found in Madagascar. The smallest lemur, the Madame Berthe's mouse lemur is the smallest primate in the world with an average body length of 9.2 cm (3.6 in) and weighs 30.6 g (1.1 oz). 

The largest of the lemur genus is the Indri with an average body length of 64–72 cm (25–28 in). Indris are the only lemurs that ‘sing’, a trait thought to be both a defense behavior as well as a method of communication. 

They are usually found in the upper canopies of the forest looking for fruit. They are considered to be the world’s largest pollinator, playing a vital role in forest health.

The silky sifaka is one of the most endangered primates in the world. It is estimated there are less than 250 of these animals left in the wild.

Probably the most recognizable species of the lemur family, these lemurs live in big social groups and eat both plants and animals such as insects and lizards.

The world's largest nocturnal primate, it has a specialized elongated middle finger which it uses to extract wood burrowing insects. 

Out of the 600 primate species in the world there are only two that can have blue eyes, Homo sapiens (humans) and the blue-eyed black lemur.

Welcome to the Malagasy rainforest. Surrounding you is the preferred food of the ruffed lemur (Varecia variegata variegata and Varecia variegata rubra). 

Male and female ruffed lemurs see differently. All male ruffed lemurs are dichromats meaning they have two cones in their eyes. They are red-green colorblind meaning they can’t tell the difference between red and green. Their world is filled with blues, yellows, greens, or a mixture of these. 

Many females share the same vision. However due to a mutation on the X chromosome some female ruffed lemurs are trichromats meaning they have three cones in their eyes, just like humans They are able to tell red and green apart. This forest is seen through the eyes of a female trichromat. 

Ruffed lemurs are mainly frugivores (fruit eaters) but will also eat leaves and nectar. These fruits are the preferred fruit choice of the ruffed lemur at different stages of ripeness. Take a minute now to look at the rest of the scene and find as many of these fruits as you can.

This is a similar rainforest scene as before, however you are now red-green colorblind, like all male ruffed lemurs.

Because two X chromosomes are needed for trichromacy in ruffed lemurs all males (who have an X and Y chromosome) are dichromats.

How many pieces of fruits can you find now? 

Fossas are predators of ruffed lemurs. Scientists are studying whether trichromatic females have an advantage spotting predators over dichromatic lemurs.

Fossas have a reddish brown coat. There are three fossas hiding in this half of the rainforest, shown through the eyes of a trichromatic female.

This half of the rainforest is shown through the eyes of a male ruffed lemur. There are three fossas hiding in this scene. 

Red-green colorblindness could be an advantage when spotting fossas. This is because these individuals can detect lines and patterns more easily than trichromats who base much of their visual information on color.