Skip to content
Skip to main content

About this free course

Download this course

Share this free course

Introduction to ecosystems
Introduction to ecosystems

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

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.Video player: eco_1_openlearn_6_10_darwins_thoughts_on_the_iguanas.mp4
Copy this transcript to the clipboard
Print this transcript
Show transcript|Hide transcript
 
Interactive feature not available in single page view (see it in standard view).

Activity 2

Why, do you think, is the marine iguana so vulnerable to sea temperature changes?

What impacts of environmental change might make the land iguana vulnerable?

To use this interactive functionality a free OU account is required. Sign in or register.
Interactive feature not available in single page view (see it in standard view).

Answer

The marine iguana feeds exclusively on a small number of species of seaweed. The seaweed needs relatively cool water and in some years, when the ocean currents reverse, the seas around the islands get too warm for the seaweed and it dies back. The marine iguanas then have no food and die in large numbers. Any prolonged warming of the seas would make the species highly vulnerable to extinction. Land iguanas get most of their water from prickly pear cacti and the rest from rain fall. Any prolonged period without rain due to changes in climate put land iguanas at risk.