Planet Earth - Episode 09 (Shallow Seas) (ATOM Study Guide)

Planet Earth is a BBC production with five episodes in the first series (episodes one through five) and six episodes in the second series (episodes six through eleven). Each episode examines a specific environment, focussing on key species or relationships in each habitat; the challenges they face; the behaviours they exhibit and the adaptations that enable them to survive. Recent advances in photography are used to achieve some spectacular 'first sights' – in particular, stabilised aerial photography gives us remarkable views of migrating animals and the techniques used by their predators to hunt them.

As the series examines pristine environments where possible, they are often extreme. These are the parts of the world where few humans have chosen to live as the climate and landscape is too challenging, too difficult and dangerous. The plants and animals that do survive here have made some spectacular adaptations in forms and behaviour to live in these far reaches of the planet.

The series is suitable for middle secondary students studying Science and SOSE, and for senior secondary students of Biology, Environmental Science and Geography.

The continents are fringed by continental shelves, waters up to 200 metres deep that may stretch out hundreds of kilometres before plunging to the abyssal depths. While they are less than ten per cent of the world's ocean areas, they hold the vast majority of marine life because this is where we find the breeding and feeding grounds.

This episode of Planet Earth ranges from the remarkable biodiversity of the tropical coral reefs to the rich polar feeding grounds, using the migration of a humpback whale mother and calf as an example to demonstrate the difference between the marine environments available to them. Why would the mature whales choose to starve themselves for half the year and what drives them to migrate thousands of miles along the coasts of Australia and other continents? On the way they may pass the great coral reefs like the Great Barrier Reef, the largest organic structures on earth and yet built by some of the smallest organisms. A symbiosis between coral polyps and algae creates rich gardens in otherwise barren tropical marine deserts, especially in Indonesia where the most diverse reefs in the world exist. Hunting packs of sea snakes work in harmony with carnivorous goatfish to flush out prey from coral crannies in astonishing scenes filmed in detail for the first time.

Away from the reefs and out on the sands, camouflage and concealment are the key to survival but the huge sea cows, dugong, can graze the seagrass meadows safely. However the fish find that even the extreme shallows are no guarantee of safety when dolphins are intelligent enough to learn to hydroplane in inches of water.

The whale has raised her calf to the stage where it can begin to feed itself and she's starving, so it's time for the journey south to the great summer feeding grounds. As the waters become colder and rougher, the nutrients are stirred up from the ocean floor by cold currents, providing food for the phytoplankton algae and seaweeds, food to power the richest marine environments on earth. The massive quantities of new green life support invertebrates like jellies and krill, food in turn for small fish and squid. Now the large fish and mammals like dolphin and seals can survive on the dense food resources and even starfish pursue each other across the ocean floor in time-lapsed mass hunts, suddenly made thrilling by the speed of the camera.