Scales or Scutes?

D

o lizards have scales or scutes? How about crocodiles? Turtles? Let’s discuss the difference between scales and scutes in reptiles…

What are the reptiles?

Turtles, crocodiles, alligators, tuataras, snakes, and lizards are all reptiles. They have a keratinised bony outer layer of skin made of epidermal plates/scales or scutes.

What are scales?

Scales and plates are structures of the outer skin of some reptiles. They…

- Start growing from the epidermis. This is the topmost layer of the three skin layers (epidermis, dermis, hypodermis).

- Overlap

- Shed and are replaced. This also helps get rid of parasites on the superficial layer of skin.

- Prevents moisture loss

- Makes it easier for reptiles to move through their environment, for example, by providing friction

A plate is basically a larger, bonier scale.  

Reptiles with scales include snakes, tuataras, and lizards.

What are scutes?

Scutes (pronounced ‘skewts’) are the shells or body armour in certain reptiles. They…

- Start growing from deeper within the dermis

- Do not overlap as they are individualised

- Shed off in some species or have new keratin perpetually growing from beneath each scute in other species. If shed, the scutes break off section by section, not all in one go like in snakes.

- Prevents moisture loss

- Are like defensive armour

Reptiles with scutes include turtles, crocodiles, and alligators.

So, what are osteoderms?

Osteoderms are hard, bony protective structures at the skin. If the reptile has osteoderms, it would lie underneath the scale or the scute. Whilst scales and scutes are composed of alpha and beta keratins, osteoderms are made of bone.

These explanations are simplistic but hopefully it’s useful! Remember to always check with journal articles and reputable sources for specific and up-to-date information pertaining to your research topics and assignments for uni! I guess the main difference between scales and scutes are that scales overlap and scutes grow out from deeper in the dermis.

Next time you see a crocodile, you’ll know to say scutes not scales!

See you in my next article Xx

Sources:

Thompson, E 2019, BIOL2032 Australian Wildlife Biology, lecture: Reptiles: Introduction, lecture PowerPoint slides, Taronga Institute of Science and Learning, The University of Sydney