Madagascar Chameleon's Short, Vibrant Life
ARI SHAPIRO, host:
If you're a gardener, you know the difference between annual plants - which die off every year, like petunias - and perennial plants, which are perennial. We expect this in plants, but animals? Well, here's the story of a young biologist who discovered that a psychedelic, green-and-white chameleon has evolved a life history that's like the petunias. NPR's Richard Harris has the story.
RICHARD HARRIS: Five years ago, Kris Karsten was earning his Ph.D. at Oklahoma State University, and he wanted to study the behavior of exotic lizards: chameleons.
He picked a few species that lived in the desert region of Madagascar, and in January of 2003, he set out with colleagues to observe these critters, including one species called Furcifer labordi.
Mr. KRISTOPHER KARSTEN (Scientist): And when I got there, one of the species I was going to study appeared normal, by all accounts. You could find adults. You could find juveniles, and everything was sort of what I expected. And then in this species, Furcifer labordi, I got there and I found nothing but adults. I couldn't find any juveniles whatsoever.
HARRIS: He thought: Maybe I'm just no good at finding juveniles of this species, or maybe there aren't any. So on his next trip, he showed up earlier in the season.
Mr. KARSTEN: Again, in the other species, everything looked as I expected. But then in Furcifer labordi, it was all juveniles, no adults.
HARRIS: Karsten and his colleagues then knew this chameleon's whole life cycle is a single year. Juveniles emerge in one burst from their eggs in November. Next, this cohort grows incredibly quickly for a month or two.
Mr. KARSTEN: Then from that point, it's just fighting and mating, basically, until they die off at the end of the year.
HARRIS: Their lifetime from hatching to death is a paltry four months or so.
Mr. KARSTEN: The rest of the time, they actually spend their life in a pretty nice, stable little environment inside the egg.
HARRIS: So most of their life is spent inside the egg?
Mr. KARSTEN: Mm-hmm.
HARRIS: That's kind of - that's bizarre, isn't it?
Mr. KARSTEN: That's what we thought.
(Soundbite of laughter)
HARRIS: Karsten and his colleagues have published this in the latest Proceedings of the National Academy of Sciences. Now, you might think it would be boring to spend most of your life curled up inside an egg with no sensory stimulus at all.
Mr. KARSTEN: I would think of it sort of in the opposite fashion. I mean, they pack a lot of life into that short span.
HARRIS: For instance, he says, mating rituals are dazzling. Females, when they reject a male, turn from green and white to black with a smattering of orange, violet, yellow and red. It's quite a show. And these chameleons have apparently adopted this odd life history in order to survive in a very harsh environment. The part of Madagascar where they live is practically a desert, and there's precious little to eat during all those months that the chameleons are dormant inside their eggs. So they're hunkering down to survive.
Eric Pianka at the University of Texas says he knows a few other species of desert lizards that live for just a year, but it is an extremely unusual lifestyle for four-legged creatures. If you look more broadly at life on Earth, species have adopted all sorts of life spans to optimize their chances of survival.
Mr. ERIC PIANKA (University of Texas) On one end of the spectrum, you've got trees that live for thousands of years, like redwood trees. On the other end, you've got annual plants that don't even live one year, and when they go to seed, they die. That's the kind of difference we're talking about here.
HARRIS: It's just that humans see the world through the lens of our own place on this spectrum. Richard Harris, NPR News.