200 million years in the future, most of the species of fish have been wiped out except for flish and some sharks, leaving most of the fish's niches vacant and silverswimmers, neotenous forms of crab, which have filled that vacancy.
Their ancestors were microscopic crab larvae which evolved to reproduce within the larval stage, and after millions of years, grew in size, to the point in which they are as diverse in size, shape and population as fish once were, and as a result they filled the void in the sea left by the absence of most fish. There are hundreds of different species of silverswimmers and they fill almost every available niche. Some are predators, some prey, some are parasites and others are scavengers. The program focuses on one filter-feeder type, although a large carnivorous type is shown briefly.
List of speciesEdit