Skip main navigation

£199.99 £139.99 for one year of Unlimited learning. Offer ends on 28 February 2023 at 23:59 (UTC). T&Cs apply

Find out more

Marine Reptiles

The Class Reptilia consist of sea turtles, marine iguana's and crocodiles. Dr. Kathy Townsend explains how they are adapted to life below water.
The next group of animals we’re going to talk about are from the class Reptilia. They include things like your sea turtles, your sea snakes, and your crocodiles. And within the class Reptilia there’s three orders. the Testudines, the Squamata, and the Crocodilia, and the Testudines includes your things like your turtles, the Squamata includes things like your marine iguanas, and Crocodilia, of course, are your crocodiles. Now there’s over 10,000 species of Reptilia. And within that the name Reptilia actually means to creep. You can find them in all kinds of different types environment for marine, freshwater, and of course, in terrestrial environments as well. So what are some of the characteristics of the group Reptilia?
Well, they have lungs that they use throughout their lives. They have what’s called tetrapod limbs, which means they have four legs. They have amniotic eggs with a leathery shell and those amniotic eggs were really important for this group being able to exploit terrestrial habitats. Unlike sharks and rays, they actually have a three chambered heart. Sharks and rays only have two. These guys are also ectothermic. Same with the sharks and rays and fish, they are too, which means that they’re actually cold blooded. And they their body temperature is dependent upon the environment that they’re actually in. They’re also covered in really tough scales. So what are some of the problems of living in the water?
Well, things like breathing, they obviously have to come up to the surface to breathe all the time, maintaining their body temperature, and of course, laying their eggs. They can’t lay their eggs in the water, they either have to they have to come back up onto land to actually lay their eggs. And can anyone think of a really famous marine reptile of any sort? I think again, going back to Finding Nemo, I think Crush, “Hey dude”, might be one of the most famous turtles that I know

Marine reptiles can be found in the Class Reptilia. Within this class there are three orders that contain marine species: Testudines (sea turtles), Squamata (sea snakes and lizards) and Crocodilia (crocodiles).

There are over 10,000 species of reptiles, but of course not all of those are adapted to the marine environment. They can be found in marine, freshwater and terrestrial habitats and they have a range of characteristics that identify them as a group.

These include, lungs that they use throughout their lives, tetrapod limbs, amniotic eggs with leathery shells, a three chambered heart, they are ectothermic (cold blooded), and are covered with tough scales.

As a group, reptiles are actually better adapted for land than they are for the marine environment. This means that living in the marine environment is challenging for reptiles as they have had to come up with adaptation for breathing, nesting, and maintaining their body temperatures.

Can you think of a famous marine reptile? If so, pop it in the chat below.

This article is from the free online

Life Below Water: Conservation, Current Issues, Possible Solutions

Created by
FutureLearn - Learning For Life

Our purpose is to transform access to education.

We offer a diverse selection of courses from leading universities and cultural institutions from around the world. These are delivered one step at a time, and are accessible on mobile, tablet and desktop, so you can fit learning around your life.

We believe learning should be an enjoyable, social experience, so our courses offer the opportunity to discuss what you’re learning with others as you go, helping you make fresh discoveries and form new ideas.
You can unlock new opportunities with unlimited access to hundreds of online short courses for a year by subscribing to our Unlimited package. Build your knowledge with top universities and organisations.

Learn more about how FutureLearn is transforming access to education