Happy International Day for Biological Diversity...Now Watch out for 6-foot Lizards!

A Nile monitor in Manhattan encounters a dog on the street. This lizard was taken in by a reptile orphanage after being abused. (Chris Hondros/Newsmakers/Getty Images)

To a 30-pound (14-kilogram) lizard, a sunny tarmac in southern Florida looks like a pretty nice place to spend the day. But to the pilots who land and take off planes from those tarmacs, a lizard-dotted runway looks like a major safety problem -- and an issue of human health.

Invasive Nile monitors, 6-foot (2-meter) lizards native to Africa, have infested a military base near Miami, according to National Geographic News. However, Florida's monitor problem is systemic in much of the state, where the warm, rainy climate and the popularity of exotic pets make it easy for the animals to set up shop in the wild.

It's hard to imagine people buying Nile monitors as pets -- I've already mentioned that they can grow to 6 feet, right? Add to that claws, strong jaws and voracious appetites (the Floridian invasives have been known to eat hapless dogs and cats). After the pets prove difficult to care for, reckless owners sometimes release them, or the animals escape.

Florida's invasive lizards dramatically illustrate a problem that's happening all over the world -- alien species establishing themselves, driving out natives and causing a host of other problems. For this reason, the U.N. is focusing its annual International Day for Biological Diversity on invasive alien species this year. Not all invasives are as toothy and poster-worthy as giant lizards in the cul-de-sac or military base, but some are just as threatening -- and costly. The Convention on Biological Diversity (CBD) estimates that "the annual environmental losses caused by introduced pests in the United States, United Kingdom, Australia, South Africa, India and Brazil are more than $100 billion." That's a lot of money, and it's a problem that everyone -- individuals, policymakers and customs officials -- will have to work together to remedy.

Related posts: Pants Full of Birds Wind Dong Behind Bars Have Invasives, Will Travel

Learn more: Invasive species Nile monitor Geography of Florida