23.2a – The Slow Loris

Slow and nervous — a toxic combination. (Sunda slow loris photo by David Haring)

In the leafy, tropical forests of southeast Asia, you may happen upon a slow loris — but you would probably never know it.

The slow loris is part of a group known as the lorisids. The ten species of lorisids live in southeast Asia and central Africa, and they include the slender loris, the potto, and the angwantibo. In general they are mid- to small-sized primates with large eyes and very short tails, if they have any tail at all.

But the slow loris is the most interesting of the lot, for one very obvious reason. It is the only type of primate in the world that is venomous.

This trait is extremely rare among mammals. The slow loris does not produce toxins directly in its mouth, but has a rather ingenious system in place. It produces a compound from a gland on its arm, and when it licks this gland, the compound mixes with its saliva to form a toxin inside the mouth. That sounds somewhat foolish and dangerous, but the toxin doesn’t harm the loris — it only harms things the loris bites.

But a slow loris is not an aggressive creature; its bite is used only in self-defense. The animal also licks the toxin into the fur of its young, so that predators will be less likely to look upon a slow loris as a tasty snack.

These precautions are important because of how the slow loris moves — as you might have guessed from the name, it moves very slowly. If you are fortunate enough to spot a slow loris in the jungle, chances are very good that it will be creeping along at a snail’s pace, or not moving at all. It has strong hands that can clamp onto a branch so tightly that it takes a serious effort to make them let go, so they have no problem just hanging around and not moving at all, sloth-like.

But what we didn’t understand about this is that the slow loris is only slow when we’re watching it. This is an interesting effect in science — the notion that a thing might change simply because it is being observed, which in turn means that any conclusions we draw from our observations may be false.

The thing is, the slow loris, and indeed all of the lorisids, move slowly when they feel there might be danger nearby, and in their eyes anything that moves is a potential danger. In their dense, leafy homes, moving slowly helps them blend in and avoid being spotted and eaten.

But put a loris in an environment where it feels safe, such as darkness, and it will move about normally, yet it wasn’t until we had the proper technology that we understood that. So we named it the slow loris, and the name has stuck. However, there is still one difference between a loris’s normal movement and what you would expect from a primate — the slow loris does not jump. At all. It has no future in basketball.

Slow loris species are either vulnerable or endangered, for two reasons. One is a reason that threatens many species in southeast Asia, namely habitat destruction from deforestation to clear land for human use or consumption. The second reason is the wildlife trade. Slow lorises are popular as exotic pets, but this is very bad for the species. In order for a slow loris to become a human pet, its teeth are usually removed so that it cannot inflict its toxic bite (which is painful but not fatal to humans). Many of these animals eventually die from infection or malnutrition after having their teeth removed.

A baby slow loris has its teeth removed with nail clippers before it becomes a pet. Yes, it’s just as bad as it looks. (Photo by International Animal Rescue)

People like slow lorises so much because they are docile, agreeable pets, but you must remember — the slow loris acts slow and docile only when it is feeling threatened. The cuter it looks, the more it fears for its life. Life as a pet is not good for a slow loris, but people all over the world own them. Since 2007 it has been completely illegal in every country in the world to import a slow loris, but exotic pet traders still find ways to smuggle them into other countries and sell them, often to people who don’t know that they are illegal.

To make a long story short, don’t ever buy a slow loris as a pet. Most die in captivity, and live unhappy existences up until they do, but so long as people are willing to pay for them because they are cute, there will be those who circumvent the law to take them from the wild and sell them.