They spend a lot of their lives in the water, they have fur, give live birth, have mammary glands etc...but my teacher mentioned that beavers have continually growing teeth (incisors) which supposedly excludes them from being marine mammals. The thing I'm confused about is that we also learned later that manatees & walruses (which are both considered marine mammals DO have continually growing teeth. I don't understand, any help would be appreciated :'(

  • 6
    $\begingroup$ It might help you to think carefully about the word "marine"... $\endgroup$
    – bob1
    Commented Oct 6, 2023 at 1:01
  • $\begingroup$ @bob1 It might help you to think carefully about the fact that beavers sometimes brave the sea. $\endgroup$
    – Araucaria
    Commented Oct 7, 2023 at 0:00
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    $\begingroup$ So do people, are we "marine"? @Araucaria $\endgroup$ Commented Oct 7, 2023 at 1:38
  • $\begingroup$ @Araucaria true, but does not make them marine any more than whales and dolphins coming into fresh water makes them aquatic. $\endgroup$
    – bob1
    Commented Oct 8, 2023 at 3:33

1 Answer 1


Beavers are not Marine Mammals

According to Wikipedia, Marine is an adjective meaning of or pertaining to the sea or ocean: as Beavers can be found in a number of freshwater habitats, such as rivers, streams, lakes and ponds, they are not considered "marine".

Beavers are semiaquatic Mammals

Their wikipedia page mention that they be semiaquatic mammals (that dwell partly or entirely in bodies of water), as the European otter, the Baikal seal, the Capybara or the hippopotamus:

Beavers (genus Castor) are large, semiaquatic rodents (...) Other semi-aquatic mammals, such as water voles, muskrats, minks, and otters, will shelter in beaver lodges.

Be nice to your teacher when you correct them about their answer: it's ok to be wrong sometime, even for a teacher! Hope it helps.


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