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Marine mammals

Marine mammals include animals such as whales, dolphins, seals, manatee and dugongs. Watch Dr. Kathy Townsend explain more about them.
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The last group I’m going to introduce you to are the mammals from the class Mammalia. Now, within the class Mammalia, there’s really only just three orders of marine species. So, there are three orders that contain marine species. The first one is Carnivora, which is the seals, the sea lions, the polar bears and the otters. The other one is the Cetaceans, which includes things like your whales and dolphins. And finally, we have Sirenia, which are your seacows, your manatees and your dugongs. Now within the Class Mammalia, there is over 5500 species, and the term mammal means producer of milk. So where are you going to find these guys?
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Well, they cover a whole range of different types of habitat, everything from marine, freshwater, and of course terrestrial. So what are some of the characteristics of a mammal and a mammal, of course that lives in oceanic environments or aquatic environments? Well, first of all, being a mammal they nourish their young with milk. Secondly, they have hair. Even things like whales and dolphins actually have hair. With dolphins, they have hair when they’re first born, and they eventually shed it. Whereas with the whales, they actually have hair sticking out these tiny little tubercles. And they can maintain that through their entire life. They nourish their young with milk, and they also undergo what’s called internal fertilisation.
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They also have a four chambered heart. So we’ve now moved up to the animals having a much more developed heart. And they’re also endothermic or warm blooded. But even though they are endothermic, living in water is really a problem. How do they keep warm? They use things like thick fur or thick blubber to maintain their body temperature. And the other issue, of course, is breathing. How do they stop themselves from getting barotrauma? And of course, they have to keep coming up to the surface to be able to breathe. Can anyone think of a famous marine mammal, perhaps from the movies or the televisions or documentaries? A couple that I can think of are things like Flipper or Blackfish.
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Well, you’ve now been introduced to all the major classes of marine vertebrates. In the next section, you’ll have a poll where we want you to basically give us an answer to let us know which group of marine vertebrates are actually your favourites and why. Talk to you next time.

Animals belong to the Class Mammalia and can be found in every habitat, including marine, freshwater and terrestrial. Consisting of over 5,500 species, there are really only three orders within the class that contain ‘marine’ species. These include, Carnivora (seals, sea lions, polar bears, otters), Cetacea (whales and dolphins) and Sirenia (sea cows, such as manatee and dugongs)

Just like terrestrial mammals, marine mammals nourish young with milk, have hair, undergo internal fertilisation, have a four chambered heart and are endothermic (warm blooded). Because of these characteristics, living in marine environments are challenging for marine mammals. However, they have developed a wide range of adaptations that allow them to breath and maintain their body temperatures while living their lives out below water.

Have you ever seen a marine mammal in the wild? Let us know your story in the chat.

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This content is taken from University of the Sunshine Coast online course
Life Below Water: Conservation, Current Issues, Possible Solutions
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