TODAY, I thought we'd dip into the animal file and see what we could find. For instance, what wild animal kills the most humans? Is it the shark? The crocodile? Well, strangely enough, for the big animals, it's the hippopotamus. But nothing holds a candle to the killer you all have in your back yard. Mosquitoes kill more than a million humans a year!

But the meat eaters like crocodiles and alligators have to rank right up there, right? Well, researchers have just discovered a dirty little secret about crocodiles and alligators. It turns out they don't live by meat alone!

A new study led by the Wildlife Conservation Society says that along with their normal meat-heavy diets of mammals, birds and fish the American alligator and a dozen other crocodile species enjoy the occasional taste of – fruit.

The researchers looked at 18 species of crocodilians ranging from the American alligator to the fearsome Nile crocodile and found 13 of them routinely consumed some form of fruit, including a variety of berries, legumes, nuts and grains.

While the authors say some of the fruit ingestion may have been incidental to prey capture, the evidence shows that other fruit is consumed deliberately and in large quantities. Now the researchers are looking at what kind of role the crocodilians play in seed dispersal in freshwater ecosystems.

So, crocs eat fruit. But that still doesn't make them mammals. I mean, they're cold-blooded and they have all those scales. Well, as far as cold-blooded goes, the naked mole-rat which is definitely a mammal, has a lot of trouble maintaining its temperature. And crocs have four-chambered hearts which is usually considered mammal territory only. And as for scales, have you looked at a picture of an armadillo lately?

So – what does distinguish the mammals from the reptiles? Well, it turns out the answer is whiskers. Researchers at the University of Sheffield in England compared rats and mice with the marsupials and they think that movable whiskers were an important milestone in the evolution of mammals from reptiles.

The scientists used high-speed video to take pictures of rats and mice moving their whiskers back and forth at high speed and in various ways to actively sense their environment in a behavior known as ‘whisking.” Whisking allows rats and mice to build an accurate map of their surroundings.

When they run in a straight line, rats and mice move their whiskers back and forth the same amount on both sides but when they turn they move their whiskers in the direction of the turn. When the whiskers on one side of their heads contact an object, those on the opposite side sweep around to gather more information.

The researchers also found that whisking is also seen in a small South American marsupial, the grey short-tailed opossum, an animal that has many similarities to mammals that lived more than 125 million years ago when modern rodents and marsupials diverged.

The earliest mammals were nocturnal, and lived in trees. To successfully move around and thrive in this challenging environment these animals needed to combine information from multiple senses: sight, sound, smell and touch. Facial whiskers provided mammals with a new tactile sense not available to reptiles, that could help them to get around in the dark.

The researchers say that moveable whiskers were an important step along the evolutionary path to modern mammals. Although humans don't have moveable whiskers anymore, they were a critical feature of our early mammalian ancestors.

Do you suppose that's why we like men with beards so much?

Cruise on over to The Deep website at www.thedeepradioshow.com to learn more about whiskers and many other topics. Enjoy!