Discovering Whales, Dolphins, and Porpoises

Discovering Whales, Dolphins, and Porpoises — page 1 — INTRODUCTION Welcome to the underwater world of aquatic mammals Many aquatic mammals are part of a big group of animals called cetaceans This group includes whales dolphins and porpoises Each of the three main groups has its own set of subgroups but they all share a few common features Cetaceans are all mammals just like humans which means that they breathe air through lungs instead of gills like fish are warm blooded instead of cold blooded like reptiles they give birth to live young instead of laying eggs like birds and produce milk like cows They may not look like it with their smooth skin but they usually have a little bit of hair or fur at some point in their life Some cetaceans have hair even before they are born called lanugo Cetaceans also have a layer of fat called blubber that helps them to stay warm in the chilly waters of the ocean but they have to come up to the surface to breathe air before they can dive down again These aquatic mammals have adapted to life in the water Instead of legs they have two front flippers or fins called pectoral fins and one long tail with features called flukes They have blowholes on the top of their head instead of nostrils and these blowholes help them to breathe when they reach the surface of the water Some cetaceans have a dorsal fin which is often a triangle shape on their backs but some do not There are two major groups of cetaceans toothed whales odontocetes which includes dolphins and porpoises and baleen whales mysticetes Toothed whales as the name suggests have teeth Some only have a few teeth and some have a full set of teeth Sometimes these teeth are used for eating but they are also sometimes used for protection or fighting if the whale only has a small number of teeth Whales that do not use their teeth to eat will suction feed which means they use powerful muscles to suck up their prey usually fish or squid and swallow it whole In general toothed whales tend to be social and live in groups called pods and they 8

Discovering Whales, Dolphins, and Porpoises — page 2 — species including some that can live in freshwater These animals are often small in size compared to whales and some dolphins and they usually live in cooler waters than dolphins Dolphins and porpoises are sometimes threatened by sharks but most whales are large enough that they are not threatened One of the biggest threats to cetaceans comes from people For years whales were hunted for their valuable blubber driving some species to near extinction Although smaller dolphins and porpoises were not hunted as aggressively as whales they are often caught in the nets of fishermen sometimes accidentally and injured or killed Like all ocean life pollution and climate change are major threats to cetaceans because changes in their habitat can affect their food supply and quality of life often use a form of navigation called echolocation in which they make noises and then use the echoes to understand their surroundings This form of navigation is especially helpful in deep or murky water where it’s difficult to see Instead of teeth baleen whales have special filters in their mouths called baleen They eat by gulping in a big mouthful of water and then using the baleen to separate the water from the food Even though these whales are very large they usually only eat very small animals such as krill plankton and small fish They typically have two blowholes and are some of the biggest mammals in the world You might be wondering how whales dolphins and porpoises are different from one another Although they’re all part of the cetacean group they are in separate families created by scientists because of their size shape and habitat Whales are the biggest of this group in size and can be found all over the world They have lots of thick blubber on their bodies which often allows them to live in very cold or very deep water Dolphins are typically smaller than whales and in general prefer warmer or tropical waters Some species of dolphins can even live in freshwater They are athletic swimmers and are often known for being able to do acrobatics and tricks Although porpoises are a smaller family than dolphins and whales there are a number of different porpoise 9

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