The Navy uses bottlenose dolphins to find underwater explosives. (Photographer's Mate 1st Class Brien Aho/U.S. Navy)

When people think about working animals, what often comes to mind are dogs that herd sheep, horses that work on farms and animals that perform in movies. But there are lots of other jobs animals have had over the years.

Dogs are much more sensitive to smell than humans. This made dogs the traditional hunting companion, enabling their owners to track foxes and other game. Police departments have taken advantage of this skill to help find missing people and escaped convicts. Recently, dogs have been trained to use their super-sniffers to find illegal drugs, explosives and even hidden computer equipment.

There is a bird in the southeast African nation of Mozambique called the honey­guide, which has developed a mutually beneficial relationship with a tribe called the Yao. If a Yao tribesman makes a certain chirping sound, the honeyguide will fly from tree to tree directing the tribesman to a hidden beehive. Once discovered, the humans break open the hive for honey, and the birds feast on wax.

Ferrets are cute, furry animals in the weasel family that range in size from 1½ to four pounds. They have helped humans for centuries. About 2,000 years ago, ancient Romans trained ferrets to flush rabbits out of their burrows to feed their troops. European settlers who came to America used them to keep rodents under control. More recently, people have taken advantage of a ferret’s natural instinct to run through tight spaces. Pipe-running ferrets wear a special harness that enables them to pull a string through hundreds of feet of pipe. The string is then used to pull cables and computer wires through the pipe.

Baby flies are called maggots. The job of a maggot is to eat and grow until it turns into a fly. This is similar to how a caterpillar eats and grows until it becomes a butterfly. However, there is a big difference between these insects. Caterpillars eat plant matter, whereas maggots devour meat. Actually, they eat only decaying meat. Medical-grade maggots are used with patients who get serious infections that can’t be treated with antibiotics. The maggots are applied to the infected area for a number of days. They eat the dead tissue but leave the living tissue alone, thereby helping patients recover from the infection.

Honeyguides are birds in Mozambique that help humans search for honey. (Claire Spottiswoode/Associated Press)

The United States military has trained marine animals for other tasks. Bottlenose dolphins can echolocate, or use sound waves to determine where an object is. The Navy has used them to detect underwater mines. California sea lions have excellent vision and have been trained to find lost equipment and swimmers who try to enter restricted waters.

In cartoons, goats are often shown eating cans and other junk. In real life, they prefer things that are green: grass, leaves and underbrush. In some parts of the country, people rent out herds of goats to clean (eat) overgrown and invasive plants. Of course, using an organic lawn mower has its consequences: goat poop.

Perhaps the oddest animal job of all belongs to Twiggy, the water-skiing squirrel. (You can find videos of her on YouTube.) Twiggy is fun to watch, but she’s also sending a message about water safety.

Bennett is a Washington pediatrician.

Goats graze at Congressional Cemetery in Washington, clearing invasive vines and other weeds. (Yuri Gripas/Reuters)