INTRODUCTION

Awed by their size, intelligence, social nature, and on the precipice of understanding their way of life in a challenging habitat, we are fascinated by the cetaceans: whales, dolphins and porpoises — air-breathing mammals with which we feel such an unlikely kinship.

The great rise in popularity of whale watching in Hawaii, California, New England, and elsewhere around the world, bears eloquent witness to our desire to see and know more about these fascinating animals. Several species of great whales have been depleted to the point of near-extinction — for oil, fertilizer, pet food, and cosmetics — before we have learned as much about them as we have about the rarest and most protected of land mammals. In more recent years, threats such as prey depletion, vessel traffic, pollution, entanglement in fishing nets, sonar testing and climate change threaten their livelihood,¬† in addition to continued whaling and direct dolphin and porpoise kills. At least one species of dolphin, the Baiji, will probably soon go extinct from our shortsightedness, and there are doubtless other species, most likely the ziphiids, or beaked whales, that have yet to be discovered.

If we are to preserve the whales, dolphins and porpoises¬† — then we must learn more about their astonishing abilities — and weaknesses. It is to that greater knowledge and the hope for their survival that this website is dedicated.

 THE EVOLUTION OF WHALES

Sometime between 70 million and 50 million years ago, after the last of the dinosaurs had died and mammals had inherited the land, one or more groups of mammals waded back into the water, presumably to feed on the abundant plant and animal forms there. These pig-sized, four-legged, warm-blooded, placental creatures adapted quickly to their new habitat and soon gave rise to a new branch in the evolutionary tree — the order Cetacea, which today includes all of the world’s whales, dolphins, and porpoises.

Three groups of cetaceans arose from the land-dwelling ancestor or ancestors. The earliest group, the Archaeoceti, or ancient whales, died out about 20 million years ago. Of the surviving groups, one, the Odontoceti, or toothed whales, evolved specialized teeth to grasp fish and other relatively large prey such as squid, while the other living group, the Mysticeti, or baleen whales, lost their teeth and developed very large mouths equipped with filtering fringes or baleen with which they trap large numbers of very small organisms. Both of these evolutionary paths proved to be successful, and each group has diversified to fill various niches. Although the demands of mobility, heat conservation, and sensory awareness in an aquatic environment have caused both groups to evolve superficially similar body forms, they are quite different animals.

Both primitive baleen whales and toothed whales derived from the archaeocetes, and they, in turn, had probably evolved millions of years earlier in the Paleocene or Lower Miocene epoch from a group of small, generalized, carnivorous land mammals called creodonts. The earliest and most primitive cetacean fossil yet found, Pakicetus inachus, dates from the early Eocene epoch (about 60 million years ago) of Pakistan; it seems to have been an amphibious creature preying on fish in the shallow waters of the ancient eastern Tethys Sea.

EVOLUTION ILLUSTRATIONS-NEW

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