Sometimes called the world's smallest monkey, the pygmy tarsier is neither a monkey nor even the smallest primate. The tiny dwarf lemur of Madagascar gets that honor. And, primatologists say the tarsier falls somewhere between the prosimians (lemurs, busbabies) and monkeys on the evolutionary scale. They are not quite monkeys, but not quite prosimians either. They have qualities of both. One classification system puts them with monkeys, another with prosimians, but yet another gives them a category all their own. I like that one best. A unique creature should gets its own special spot.
Tarsier traits in common with lemurs, busbabies and other prosimians:
- grooming claw: This is a sharp nail, usually just one on each hand or foot, and often only on the hands or the feet. It's used for keeping clean.
- bicornate uterus: Rather one pouch for growing babies, these guy have a uterus that is V shaped, providing two pouches. This makes it much easier to have more than one baby at a time, though like monkeys, tarsiers usually one have one baby at a time.
- two pairs of nipples: Only the top set is functional. The other is vestigial and doesn't produce milk.
- small body size: Prosimians tend to be noticeably smaller than monkeys and apes.
- nocturnal: Tarsiers are creatures of the night. They have the large eyes to prove it too.
- no tapetum: The tapetum is a layer of the eye that reflects light. It helps nocturnal animals see better in the dark by amplifying light. When animal eyes glow at night when light hits them, it is the tapetum you're seeing. Monkeys, apes, and tarsiers don't have a tapetum. Tarsiers lack a tapetum even though they are nocturnal which suggests that tarsiers may have once been diurnal and became nocturnal in response to some change in their ecology, for example, the addition of new predators or competitors. They now occupy the same ecological niche that owls do.
- dry nose: Monkeys and apes belong to the group called 'haplorhines' as opposed to the 'strepsirhines' or wet-nosed primates (the prosimians). Tarsiers have dry noses.
- central fovea: The part of the eye's retina used for high-acuity and color vision.
- reduced olfactory bulbs: A part of the brain specialized for processing scent. Prosimians communicate with smelly secretions much more than monkeys do. Scent isn't totally irrelevant for monkeys and apes, it's just that visual and vocal communication take precedence. Perhaps this is because at night, when most prosimians are active, it is either impossible to communicate visually or downright dangerous to communicate out loud. Singals may not be seen through the dark of night or may be heard by predators. It's much more stealthy to communicate with scent.
- flexible upper lip: This greater freedom of movement, due to more as well as more complex muscles, allows monkeys and apes to make facial expressions. This is one of the big reasons why people see reflections of humanity in their primate relatives. The look of joy, boredom, anger and more can all be seen displayed on the faces of monkeys, tarsiers included.
"They always look like they have a perpetual smile on their face, which adds to the attraction," she said in an interview. To me, they look almost exactly like Furbees, that fuzzy, robotic toy that was insanely popular about a decade ago. I think even my grandma had one.
The cute yet enigmatic little primate, neither monkey nor proto-monkey, weighs a mere 2 ounces and eats mostly insects. They are also known to eat snakes.