Equator

Challenged by cycles of famine and abundance, the iconic species of Equatorial Africa have adapted to suit their unique environments. FOR MUCH OF the year the African Savannah bakes under the oppressive Equatorial sun. The dryness is unusual for the Equator, whose regions are often covered with dense rainforests and associated with a seasonless annual cycle. But the Savannah is a product of unique circumstances, of profound geological events that have combined to create a habitat for many of Africa’s iconic mammal species. Thirty million years ago part of east Africa was torn apart. Massive volcanic activity combined to form the beginnings of what would be the Great Rift Valley. Over millions of years the valley widened and grew longer, spreading north and south for more than 4,500 kilometres. The resulting mountain ranges rose 3000 metres, blocking clouds coming from the west and creating a rain shadow over east Africa.

The Indonesian archipelago in the Indo-Pacific Ocean comprises thousands of islands, atolls and the largest concentration of coral reefs in the world. This rich and varied environment is a product of a unique set of natural circumstances. The equatorial sun powers ocean currents among the tiny dots of land. Where the archipelago meets the western tip of New Guinea an intersection of ocean currents creates perhaps the world's richest reefs in the region of the Rajah Ampat Islands. A coral reef houses a myriad of colours, shapes and patterns: from the bulb tentacle anemone which protects, and in turn is protected by, the brightly coloured clownfish; to the multi-branched gorgonian, home of the tiny pygmy seahorses. Coral animals have tiny symbiotic plants living within their tissues. Brought together by sunlight, it is one of the most powerful biological partnerships on earth. Young coral ingest free-swimming algae, but because of some ancient genetic signal, the algae are not eaten. Instead the coral wraps the tiny plants in membrane and moves them to tissues exposed to light. The algae are nourished and in response produce sugars that both they, and the coral, consume increasing the corals growth rate. Coral is far from a passive inhabitant of the ocean and once a year many species combine for an event that is both spectacular and of scientific intrigue. A mass spawning, which usually occurs during a full moon, provides not only a breeding opportunity, but also inter-breeding between coral species. It is this ease and adaptability of hybridization that is leading scientists to re-examine the most basic elements of what comprises a species.

AT THE EQUATOR dawn arrives with astonishing speed. In the rainforests of Sumatra and Borneo, it’s the tops of giant dipterocarp trees which catch the first rays of intense sunlight. After 12 hours darkness the abrupt return of the light is greeted by the operatic displays of the gibbons; just part of a dawn chorus as varied and overpowering as any on the planet. Nurtured by equatorial heat and year-round rainfall, the forest stretches up to 80 metres tall. The huge canopy trees have straight pillar-like trunks and umbrella-shaped crowns, which influence all the lives below. Not only do these “selfish giants” catch much of the sunlight and monopolise the nutrients from the forest floor; their leaves produce poisons making them unpalatable. So their massive resources are locked away from most forest creatures. What’s more the gaps between their gigantic trunks create aerial canyons that must be crossed – in astounding ways.