Marine mammals and the marine environment
Tens of thousands of millions of years ago, certain land mammals ventured into the oceans. They evolved, transformed, and through diverse evolutionary histories became the marine mammals we now know and love.
The most incredible story is that of the cetaceas
Cetaceas, dolphins and whales evolved from a walking land animal which existed 50 million years ago. In the following 12 million years, a number of spectacular transformations occured: the head became elongated, the nostrils moved toward the top of the skull in order to breath at the surface whilst maintaining the head underwater, the hind limbs disappeared and the fore limbs became flat flippers, fur was replaced by a layer of blubber and the caudal fin developped.
Sirenia and pinniped: Marine mammals and the marine environment
Although they evolved from a different ancestor, sirenia (manatee and gugong) share many characteristics with cetaceas: aquatic life, elongated body, fore limbs which have become fins and hind limbs which have disappeared completely.
Pinnipeds include seals, elephant seals, sealions, walruses, polar bears and sea otters. Unlike cetacea and sirenia, these carnivorous marine mammals are not limited to the ocean.
Over 120 species worldwide
There are over 120 species in all of the world's seas and oceans, some of which are semi-aquatic and some which are uniquely aquatic.
French coasts welcome a great diversity of marine mammals, and around one third of the world's species have been observed in there at least once.
In France, all marine mammals are protected: today it is forbidden to destroy, catch or hunt them (law passed in July 1995).
Marine mammals in Brittany
The waters surrounding the Breton coast provide a link between the Channel and the Bay of Biscay, opening onto the Atlantic. This unique geographical location makes it a perfect place for many marine mammals to visit. During the last two decades around 30 species of marine mammals have been observed at least once in Brittany. Others, such as bottlenose dolphins, gray seals and harbour seals, are present all year round.
Marine mammals and human activity
Today, marine mammals live side-by-side with numerous human activities which, depending on the region, the season and the species, can have a direct impact on the animals and their habitat. Chemical and bacterial pollution, litter, intensive fishing, noise pollution, urbanisation and industrialisation of our coasts, along with ever-increasing maritine traffic pose just as great a threat as hunting, which is still a menace even if it has greatly reduced.