Sexing the Single Caiman

I suppose some people would look at this gatorbelly and think what a nice pair of boots it would make. That kind of lust for its beauty put the black caiman in a huge downward spiral from the 1950's to the '70's, and it's only just recovering from the slaughter. Black caimans, like so many creatures persecuted elsewhere (giant otters, for one), are still common on Guyana's beautiful Rupununi River. I am so thankful for Guyana, for the Rupununi, for huge reptiles that make a swirl in the water.

I looked at the caiman's tiled abdomen and said a prayer to all that is beautiful and perfect just as it is.

Ack. What are they doing?

Feeling for conclusive evidence of the giant caiman's sex, that's what. Think fetal sonograms: If you don't feel anything, it's a female. Male caimans, like all reptiles, and all aquatic creatures as I think about it, keep their wedding tackle inside until they need it.

I resolved not to shake Ashley Holland's hand when I thanked him for our excellent nocturnal adventure.

And it was a female, and her toes curled when they did the internal exam. Awww.

"They always do that," our leader commented. It felt disrespectful to laugh, so I covered it up with a little wheezy cough.


Because there are not too many places where you're going to be able to look close-up at a caiman's vent, here it is. I was awestruck. I had this flood of images running through my head, of cells dividing in the embryo, of God with a sewing machine, of somebody or some antic evolutionary force figuring out how to resize and then upholster those Formica scales smoothly over living muscle and make them fit, flexibly airtight, around a sphincter. Ye gods. Design, functionality, beauty and awe in a caiman's bunghole.


I am in Science Chimp heaven. Again. Geeking out, hands on a ten-foot, three-inch wild female black caiman. That's as big as she will probably get. Who knows how old she is? Whether she'll keep growing?

Males can get to 16.5 feet, and Wikipedia says "The largest reported black caiman, measuring 7.7 meters (25.2 ft) and weighing 1,310 kg (2,870 lb), was shot in Acre, Brazil in 1965 and, which if accurate, would count as the largest crocodilian recorded besides saltwater crocodiles."

Pause to let that sink in. Look around, eyes crossing. That's four feet longer than my living room. A twenty-five-foot-long black caiman? How would it even turn around in smaller rivers? How old must it have been?

and how I wish they'd marked and released it instead of shooting it. (It would only take about 20 men to hold it down, c'mon!) Here's the thing. Some reptiles are said not to stop growing over their lifetimes. Kind of like fish or lobsters...you haul up this leviathan, and the first thing you have to wonder is how old it must be.

Now, for the first time, right in front of my astonished eyes, researchers are getting growth and allometric and reproductive data on this species. To find out more about the study, initiated by herpetologist and conservationist Peter Taylor, please click the link. The study involves local Amerindians, who are learning first hand how to study and protect the species, and realizing the benefits from the ecotourism that follows having a healthy population of a spectacular reptile (not to mention a spectacular mustelid, felids and endless fabulous birds).

By a clipped scute on her tail, they knew she was a recapture. So they could compare how her measurements had changed since the last time they had her in the noose. This is how we learn, this is how we answer the questions I've posed and so many more.

It was kind of upsetting to see the wrassling necessary to subdue a study subject, but it was all good. For everyone but the caiman, I suppose. She was not enjoying herself anywhere near as much as I was.

Zick, a bundle of firing synapses barely contained by her Life is Good shirt. Photo by Erica Gies.

There there, old lady caiman. They're almost done with you now.

Measurements and sexing all done, it was time to truss the poor girl up like a Thanksgiving turkey so no bits would hit the ground when she was being hoisted up on the hanging scale.

Somewhere I wrote her weight, in the dark, maybe in my little notebook. I can't find it. I found some scribbles, but the weight isn't among them. Rats. At this point all us Marlon Perkins pikers were really, really ready to see the Jim Fowlers put her back into the water, free of all this manhandling.

The Guyanan assistant tied the most amazing knot to keep her jaws closed while the noose and the tape was removed. It could be loosened with just one tug, like the sewn seam on a 50-pound bag of bird seed. I watched him tie it, careful but lightning fast, and all the wonder I felt at the caiman's perfection leapt over to those beautiful hands. Homo sapiens is one boffo primate.

They carried her to the water's edge--grunnnnnt!-- and pulled on the magic knot with a long cord.

One tug, and she was free, and nobody had to lose a hand untying her jaws. Pretty dang slick.

The whole time she was lying trussed up she was sighing, a deep, watery rumble from her very guts, and the sound moved me, as the sighs of a beached whale would. It was good to see her great jaws come open, and she said Ahhhhh again and then she was gone, just a huge muscular lash on the water's surface.

And silence, and the sound of my own breathing.