Introduction to ecosystems
Introduction to ecosystems

This free course is available to start right now. Review the full course description and key learning outcomes and create an account and enrol if you want a free statement of participation.

Free course

Introduction to ecosystems

6.3.2 Darwin’s thoughts on the iguanas

The marine iguanas of the Galápagos are the only marine lizards and occur nowhere else. They occupy a fragile ecosystem that is very vulnerable to changes in sea temperature. There is also a species of land iguana on the islands.

Download this video clip.
Skip transcript


Darwin’s thoughts on the iguanas

Some of the most remarkable creatures encountered by Darwin on the Galápagos were its iguanas. He was particularly fascinated by the marine variety though he was far from flattering. Darwin wrote that they were hideous-looking creatures of a dirty black colour, stupid, and sluggish in their movements. He did concede, however, that they were strong, graceful swimmers. Bearing in mind how much time they spent in the water, Darwin was surprised to find that marine iguanas didn't eat fish. He dissected several creatures and found that their stomachs were full of seaweed. Darwin noticed that the water was too cold for marine iguanas to stay in for a long time. When they weren't feeding, he observed them clinging to the rocks above the shoreline, basking in the sun. After the cold sea, these reptiles craved warmth. Darwin was also interested in their terrestrial cousins, although again, he wasn't very complimentary about their appearance. He called them small, ugly animals with a singularly stupid appearance and lazy, half-torpid movements. Today they're still plentiful on some islands. But marine iguanas are particularly vulnerable to changes in sea temperature, which can have a dramatic effect on the availability of seaweed.
End transcript
Copy this transcript to the clipboard
Print this transcript
Interactive feature not available in single page view (see it in standard view).

Activity 2

By signing in and enrolling on this course you can view and complete all activities within the course, track your progress in My OpenLearn. and when you have completed a course, you can download and print a free Statement of Participation - which you can use to demonstrate your learning.

Click on 'SIGN IN to enrol' to get started.

You can find out more about registering and OpenLearn in our FAQs.

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has over 40 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to university level study, find out more about the types of qualifications we offer, including our entry level Access courses and Certificates.

Not ready for University study then browse over 900 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus