Group living increases chance of survival
Many animals live in large groups or colonies in order to survive.
Plains animals such as zebras, antelopes and wildebeest have nowhere to hide so they roam the open grasslands in herds of hundreds or thousands to reduce the chance of being attacked.
Some keep a look-out while the rest feed.
When fleeing an attack, their sheer numbers confuse their predators.
Lions, hyenas and wolves live in groups because it's hard to kill the prey alone.
Having chosen a victim, the team spreads out to approach it from different directions, trying to separate it from the herd.
They then make a combined attack, chasing their prey till it tires so they can pull it down together.
Roosting together helps bats conserve energy - when they roost alone they are more restless.
An amazing 20 million Mexican free-tailed bats can be found hanging in a single cave in Texas! This roosting group also helps maintain the right temperature and humidity levels inside the cave.
As there are few suitable caves for the Garter Snake of North America to hibernate in, thousands of them slither into a tiny space and hole up together in a tangled mass.
Snakes usually breed soon after rousing from hibernation so living together means they can find a mate quickly.
Certain fish swim in schools of many thousands. They all swim in the same direction, speeding up, slowing down and turning together.
This formation swimming means turbulence from others is avoided, drag is reduced and all swim more efficiently.
Social bees and wasps - and all ants - live a highly organised life in large colonies.
A single nest may contain as many as 20,000 wasps.
As well as the one queen who only lays eggs, there are thousands of infertile worker wasps.
Some act as builders, keeping the nest in good repair, while others collect food and care for the grubs.
All are dependent on each other - none could survive alone.
Both cormorants and pelicans co-operate when fishing, driving shoals of fish into a restricted area.
The crowded fish make it easy for the birds to seize their quarry when they dip their bills into the water.
WWF HK is a local charity environmental organisation established in 1981 which aims to build a future in which people can live in harmony with nature. For information, call 2526-1011 or e-mail to http://www.wwf.org.hk