QotW - Why are crocodile scales so bumpy?

Snakes are smooth, so why are crocodiles?
22 June 2021


A sleeping crocodile, laying on a rock



Johan asked us: "Why is a crocodile's skin bumpy and not smooth?"


This week, Sally Le Page has had a large scale problem to solve, so she enlisted the help of James Hennessy, from Ireland's National Reptile Zoo...

Johan - Why is crocodile skin so bumpy and not smooth?

Sally - Johan is clearly a fearless explorer who’s not afraid to get up close and personal to big predators in the name of science. To help us out, we need an equally fearless expert: James Hennessy from Ireland’s National Reptile Zoo:

James - When we think of crocodiles, we usually think of big scaly beasts with sharp teeth. The skin of some is bumpier than others - and there are 24 different species of crocodilian.  These bumps, or scales, are really important for crocodiles, and maybe one of the reasons they've survived since before the dinosaurs! All reptiles have these scales, it's one of the reasons we call it a reptile. These strong bumpy scales help to protect them from predators and injury. In the case of crocodiles, that injury can come from other crocodiles! So if you need to protect yourself from another crocodile's sharp teeth, what better way than an armour of big thick bumpy scales!

Sally - Crocodiles attacking other crocodiles? I do not want to be in the water when that happens! But the bumpy skin is for more than just fighting. Turns out these thick skinned creatures have a warmer side to them:

James - These bumpy scales, called osteoderms, have another really important, and really cool function. They work like mini solar panels, gathering heat from the sun and helping the crocodile to get the same energy that we would get from food. They can move blood from cooler parts of their body, into these bumpy scales, and heat it up! They don't even need to expose their entire body to the sun, and so can hide mostly underwater and still stay warm. That's a great skill if you need to sneak up on your prey!

Sally - I’d love to be able to stay warm from the sun while swimming in cold water. Maybe these crocodiles are onto something! On the forum, Evan and Alan both pointed out that while crocodiles have these big bumpy scales on their backs, the scales on their bellies are quite smooth, useful if you’re dragging your belly through the mud. But one forum user, bored chemist, had a much more practical answer: Why is a crocodile's skin so bumpy? Well, have you ever tried to iron one? Next week we’ll be droning on about Covid again with this question from Paul

Paul - If one is recovering or has recovered from Covid, would playing bagpipes help to expand the lungs and be beneficial or detrimental?


Add a comment