The Smallest (and Cutest) Monkey Species on Earth

I have visited Artis, a zoo located in the centre of Amsterdam, numerous times. It is home to many animals, but one of them has always been my favourite: the pygmy marmoset. Last time, I observed it for about one hour while taking many pictures; the species is not only cute, but also has amazing model qualities. Once having arrived home, organizing the photographs got me wondering about the animal’s natural habitat and behaviour.

Small Monkey, Long Tail

The ‘Cebuella pygmaea’, or pygmy marmoset, is the smallest true monkey species in the world. Its total length is about forty centimeters, but the tail makes up about 70%. The animal weighs only slightly more than 100 grams. They are spread over five countries in South America, with evergreen and river-edge rainforests as their preferred natural habitat.

A Well-Adapted Food Specialist

The pygmy marmosets are flexible omnivores. However, they specialize in feeding on tree saps. After creating holes in the bark, the monkey licks up the subsequently flowing gum with its tongue. Some adaptations make the animals perfect for this feeding behaviour. Their specialised incisor teeth stimulate the sap flow by gouging the trees. As the gum is hard to break down in the stomach, a large cecum is helpful, allowing for a longer digestion time. The tree saps again attract insects, which are also eaten by pygmy marmosets. The animals don’t say no to nectar and juicy fruits here and there either.

Athletics of the First Rank

To reach these nutrient-rich places, the monkeys need more than average climbing ability. Their sharp nails aid in clinging to branches and stems, bringing them up to about 20 metres. Pygmy marmosets can also leap to a tree as far as 5 metres away. Finding food is not the only advantage to climbing; most of the monkeys’ predators are also lurking in the grass below. Pit viper snakes, tayras, and large cats form their biggest concerns.

Family and Intelligent Communication

The social structure of the monkeys further aid in escaping predators. The marmosets live in troops of around six individuals, including at least a dominant male, a breeding female and some offspring. Care for the litter is shared between all other group members. For this type of social interaction to work, a complex communication system is needed. Firstly, visual displays are used to show dominance or threatening behaviour. Moreover, chemical signaling by the females give cues as for when she is ready to reproduce.

But the pygmy marmoset is most well-known for its inticrate system of calls. The ‘long call’ is used when the group is spread out, and two other contact calls are used from up closer. These three main signals differ in frequency, depending on the required travel distance. Low frequency can travel further, as they are affected less by disturbances in the forest; so this is used for signalling from afar.

The Downside of Being Cute

Unfortunately, the pygmy marmoset has not long ago been listed as a vulnerable species by the International Union for Conservation of Nature. There are two main reasons the monkey is not doing as well as it used to. Habitat loss by deforestation is one, and wildlife trade is another. The pygmy marmosets are ‘simply too cute’; they are captured for exotic pet trade due to their small size and compliant behaviour (read: because humans are douchebags).

The first pygmy marmoset arrived in Artis in 1903, and since they have been amongst the most popular in the zoo. They aren’t shy either; usually, the marmosets jump and climb around other monkey species and tourists. I can’ t wait to revisit my favourite animal once the COVID-19 pandemic is over and the zoos open their gates again.

Stay updated for a post about the ethics of visiting animal zoos!

Thanks for reading! I hope you like my post. I am Mo Schouten, a Biology student located in the Netherlands. Capturing my environment with a camera is what I love most. — — Comments as well as tips are always welcome; leave them below!

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About Artis’ zoo, home to the pygmy marmosets photographed above:

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