I love reading the news and finding cool animal stories. Cool animal stories are the best kind of news!
The news inspires this week’s animal, the crested anole (Anolis cristatellus). This little lizard (also called the common Puerto Rican anole) has recently been featured on NPR for their quick adaptations to living in cities. I’ll get into that in a bit; first, some basic anole facts!
There are over 250 species of anoles, which are small, tree-dwelling lizards related to iguanas. Like geckos, anoles have large finger and toe pads that let them climb and move quickly, even over a smooth surface.
Crested anoles are native to neotropical areas like Puerto Rico and the Caribbean. They have also been introduced to Florida, the Dominican Republic, and Costa Rica.
This species is an arboreal anole species, meaning they like living in trees. But that doesn’t mean they only live in trees; crested anoles have begun moving from the forests into cities and suburbs. In these areas, they’ll perch on walls and fences.
Break a tail
Like many other lizards, crested anoles will lose their tails if they need to escape from a predator. This is also called ‘tail autotomy’ or ‘tail-shedding.’ Now, it’s important to know that the entire tail isn’t lost; instead, they only lose a part of their tail. This broken-off part will flop around and distract a predator while the anole escapes.
While it sounds drastic, tail-shedding isn’t life-threatening to an anole. It’s better to lose a tail than your life! Still, tails are often a source of stored energy. Losing your tail is like us losing access to our fridge – we’ll survive, but we’ll be weaker for a while. Anoles without a tail may also have trouble sprinting or climbing.
But don’t worry – the tails aren’t gone forever! Broken tails grow back but are usually shorter than the original tail. In addition, the tails are made of cartilage instead of bone. Unfortunately, this cartilage rod doesn’t have the ability to shed; if an anole needs to shed its tail again, it has to make a break higher up on the tail where there are still bony vertebrae.
They work out
Crested anoles are quite territorial and will aggressively defend their territories when mating. However, males will rarely physically fight with each other.
Then how do they defend their territories, you ask?
Easy: push-ups.
Crested anoles will perform a push-up display to assert dominance. They’ll also display their dewlaps (the piece of skin underneath their neck). You can watch an anole doing some push-ups here.
Evolution in action
Okay, here’s the fun science news: the physical differences between city-living and forest-living crested anoles is genetically based!
Remember how I said earlier that crested anoles have begun moving into cities? Well, this movement has changed the crested anole. City-dwelling crested anoles have adapted to their urban environment. For instance, city anoles have longer limbs that let them run quickly across hot parking lots. They also have special scales that help them hold onto surfaces smoother than trees (i.e., walls and glass).
A recent study looked at the genetic underpinnings of these differences. After catching crested anoles in 3 Puerto Rican cities and the surrounding forests, they compared the genomes of the populations. They found differences between the populations in genes important for limb and skin development. These differences would explain the long limbs and special scales of the city anoles!
I find it so interesting how animals can adapt to thrive in urban environments. As urban areas continue to increase, we’ll likely see more animals making these kinds of adaptations.
Who knows? Maybe one day, city-dwelling humans will be slightly different than rural ones.
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