Read the passage and choose the appropriate title.
The creatures of the sea spend much time eating or trying to stay alive and not to be eaten by other sea creatures. It is not easy to stay alive and not to be eaten in such a place as the sea-bed. Almost all sea creatures are meat eaters, except the smallest animals. Now you can well understand that sea creatures have «invented» and developed many interesting ways of defending themselves from their enemies. First of all, the size of the animal plays a role in its struggle to stay alive. Some fish have developed great speed of swimming. Many of the bottom creatures have hard shells which they «shut» when danger is coming. Colour helps sea creatures in their struggle against their enemies at every level of sea life.