Wild Caribbean reef fish anywhere in the Caribbean. The final island to be featured is Trinidad, cut off from South America by rising sea levels 2,000 years ago. Its island fauna include many mainland species such as red howler monkeys, capuchins and scarlet ibis. Coral reefs, which thrive in the warm, shallow waters around Caribbean Islands, are the subject of the second programme. Hard corals are the reef-builders, and grow their tough external skeletons by extracting nutrients from algae growing within them. Time-lapse footage shows coral polyps emerging at night to trap drifting plankton. Marine life featured includes Caribbean reef squid, octopus
Cliffed coast Königsstuhl on the island of Rügen is a good example of a dead cliff. Others may be found in the regions of the present-day Wadden Sea coast of the North Sea a few kilometres inland. These show the former coastline from which the sea retreated as the level of water in the North Sea fell. Steep sea cliffs can also be caused by catastrophic debris avalanches. These have been common on the submerged flanks of ocean island volcanos such as the Hawaiian Islands and the Cape Verde Islands. Cliffed coast A cliffed coast, also called an abrasion coast, is a