Sunday 2 July 2017


Image: Artur Pedziwilk
Iguana iguana
There are Marine Iguanas, Desert Iguanas, Land Iguanas and Rock Iguanas, but if anything can be called, quite simply, The Iguana, then this is it.

It's so incredibly IGUANA that scientists named it Iguana iguana!

Image: Alfonsina Hernández Cardona
Some call it the Green Iguana. Oddly enough, while Iguanas are always very, very Iguana, they're not always Green.

The Iguana is a widespread species, with a range that extends from Mexico through to most of Brazil and many Caribbean islands.

Image: Cheryl Harleston
A lot of them really are green, as bright and vibrant as the rainforests they live in. Others are more of a pale, greyish green. On some of the Caribbean islands, they may be black or pink; in Costa Rica, you can find red ones; in Mexico, orange.

Coupled with the brown stripes some of them have and you could almost call them Tiger Iguanas!

Image: Cary Bass
Or dragons? Some of these guys look like they really ought to breathe fire. They don't, though. Which is good because if they did, they would be in danger of burning down their own homes.

Iguanas are arboreal, which means they spend most of their time in trees, clinging to the bark with their impressive claws. They need to keep to the larger branches because Iguanas are big lizards, reaching some 40 cm (16 in) long, not including a tail that can be more than twice that length.

Video: andrenegwer

The Iguana lends its name to an entire family, Iguanidae, which contains almost 1,000 species. The only Iguanids that can match the Green Iguana in size and weight are certain species of Rock Iguana, and as the name suggests, Rock Iguanas prefer to rest their weight on the ground rather than tree branches.

Nevertheless, Green Iguanas are able climbers. It's just that they spend almost all their time doing nothing at all and the rest of it eating. They have sharp, serrated teeth which they use to munch on tender leaves and flowers.

Iguanodon teeth
In 1822, a palaeontologist called Gideon Mantell discovered some enormous teeth in England's South Downs (very green, very pleasant). He didn't know what kind of animal it came from, and neither did anyone else. It was suggested they may have come from a fish or a mammal, but Gideon wasn't convinced.

It took a few years, but he finally realised that they looked a lot like Iguana teeth. Only twenty times bigger.

Image: Ian Wright
Iguanodon, mid-18th Century style
Iguanasaurus was born! And then someone suggested 'Iguanodon' instead and Iguanodon was born! It was one of the first dinosaurs to be officially named and described. They got it completely wrong, of course. They thought it was a huge lizard, smothered in sloth and idleness. It was almost thirty years before they discovered enough fossils to see the lean, front legs which suggest Iguanodon was a biped.

These days, they can even see that young Iguanodon probably spent most of their time on two legs and older, heavier ones spent more and more time on four! It's a bit like the Riddle of Sphinx.

Video: and reneger

While real Iguanas do like to spend copious amounts of time sitting in a tree, watching the world go by, they're not quite as sluggish as all that. They can climb trees, obviously, and they can run pretty fast when predators get too close. They also prefer to live close to bodies of water so that they can jump into the nearest river and swim away. They're good swimmers, letting their legs dangle at their sides and as their swishing tail powers them through the water.

And they're not sluggish at all when cornered. They'll puff out their body, prick up their spines and use a special bone in their neck to extend their dewlap, making them look as big and dangerous as possible. They'll hiss and bob their head up and down to show predators that they're ready for action. And if that doesn't work, all bets are off. They'll defend themselves with everything they've got, biting with those sharp, serrated teeth, lashing with their whip-like tail and slashing with their claws. You can't say they didn't warn you!

Image: Don Loarie
That's not the only action an Iguana has to be ready for. During the dry season, males use their spikes, dewlap and head-bobbing to defend their territory from rival males and to show the ladies that they can really move when they want to. It's just that they don't often want to.

A sufficiently impressive male will mate with all the females in his territory. Females then lay up to seventy eggs in a burrow she digs in the ground. Eggs hatch about three months later, just as the rainy season begins, which ensures there are lots of fresh leaves for the youngsters to eat.

Video: BBCWorldwide

Young Iguanas look like tiny versions of their parents. They're a lot more vulnerable, though, since it's difficult to make yourself look big and scary when you're only a few inches long. Despite that, baby Iguanas grow into adults not just within their native territory, but far from home, too.

Iguanas are considered an invasive species in parts of Texas, Florida and Hawaii. They can also be found in Fiji, on the other side of the world. Also, in 1995 a gang of Iguanas spent about three weeks on a raft of trees that got uprooted during a hurricane. They drifted some two hundred miles across the open sea until they reached the Caribbean island of Anguilla, where they set up a brand new population. You can see how ancient Iguanas could have ended up on the Galapagos Islands!

Image: Sureshdias
Clever girl
A big, sluggish lizard has to be one of the stranger invasive species out there. But drifting around on a raft of uprooted trees really plays to their strengths. I can imagine them hanging out in the trees as the hurricane came, and then yawning as the trees fell into the sea, and then dozing off as they drifted for a few months.

They didn't so much crawl out of the Jurassic as drift on the currents of time.


elfinelvin said...

A beast of noble bearing! Wish we had some around here but I'm afraid our snowy winters wouldn't suit them.

Joseph JG said...

There's definitely a certain regal quality about them! You get the sense that they should really be resting on a little horse-drawn carriage and watching their domain pass by through the window.

Rick (Ratty) said...

Very interesting and detailed information about iguanas. I'm glad I read it.

Anonymous said...

Iguanas can get much bigger than 16 inches. I lived in Panama and remember iguanas stretching all the way across a two-lane road. That's at least 8 feet! They'd get as big around as your leg.

Joseph JG said...

@Ratty: Thanks, glad to hear it!

@Tim: Wow, that's crazy! I don't know why, but I'm always happy that there are still some huge, monster lizards in the world.

BK said...

Iguana social life is actually very complex: siblings will even sacrifice themselves to save each other from predators. A lot f cool studies have been written on their societies.

Joseph JG said...

I better look for some of that, I love the idea of an iguana society!

Joseph JG said...

Ha! Yeah, it seems appropriate!