Most of the animals have are both hunters and the hunted. They have to search for food on a daily basis, yet at the same time they must be vigilant, in order to prevent attacks by their enemies. In order for so many species to be able to coexist, they are all forced to distance themselves from all of the others. Due to this, highly specialised life forms have developed during the course of evolution, which is not only reflected in the many shapes and colours of the sea-dwellers, but also their differing hunting methods. Groupers, or jewfish, who creep up on their victims then descend on them at lightning speed, employ entirely different methods than the frogfish, who, with their traplike mouths lay in wait for their prey. The mantis shrimp on the other hand has perfected its visual system to the highest degree. In this film, viewers learn why the hunting successes of these predatory crustaceans are especially dependant on their unusual eyesight. That certain fish can make noises is a known fact, but how do they detect the sounds in their watery environment? How significant are cleaners in the lives of their host fish? Answers to these and many other questions are explained in this film, supplemented with exquisitely colourful underwater footage.