Smithsonian National Zoological Park l Friends of the National Zoo



by Terry Dunn

Monkeys are always popular animals to watch at the Zoo. Here are some special things about monkeys to look for during your visit to the howler monkey exhibit:

Monkey or Ape?
There are several differences between monkeys and apes, but the most obvious difference is that, in general, monkeys have tails and apes don’t (all New World monkeys have tails).

Both have relatively long arms and legs, but the limbs of monkeys are similar in size while apes have long arms relative to their legs. When you watch the howler monkeys, look at how many ways they can use their limbs. When is the last time you could hang from a bar with one hand or put your foot in your mouth?

Male or Female?
The male of the black howler monkey species is black, the female is brown in color. Females are about 80 percent the size of males.

Opposable Thumbs
Monkeys and apes have thumbs that are higher up on the palm than the rest of the fingers so the thumb can work with the other four digits to grasp branches or food. Howler monkeys also have five-toed grasping feet, including an opposable thumb. To gain a new appreciation for opposable thumbs, try writing with a pencil without using your thumb.

Prehensile Tail
Take a look at the underside of a howler monkey’s tail and you will find a long, bare section towards the end. This is because they use their tail like a hand, grabbing branches as they move through the forest. The lack of fur helps them to grip better. As an enrichment exercise, Zoo-keepers will provide the howler monkeys with special feeders that make them use their grasping tail.

Forward-facing Eyes
Part of the reason monkeys look so much like us is because their eyes face forward like ours. This means that they have binocular vision, which helps monkeys judge distance better than animals with eyes on the sides of their heads. Forward facing eyes are a real advantage when navigating through an intricate web of forest branches.

Howling at the Rain
Howler monkeys have a curious reaction to heavy rain. As a rainstorm approaches or begins, they often start an excited chorus of howls. During the brunt of the rain though, they hunch over and look miserable.

Ready to hear a howl?
Check out the Small Mammal House to see the howler monkeys with your own two forward-facing eyes.