one of the wildest animal facts i’ve learned is that manatees actually have SUPER low body fat, they’ve just got big skeletons and incredibly dense bones. i always thought they were soft n chubby.. but they’re really bone monsters
animal skeleton, manatee science
look at those rib bones! they're SO thick. surprisingly, though, their bones aren't very strong - high mineral density is probably why. anyway, the lack of fat is why they can't stand temperatures under ~68 degrees and tend to migrate either south or to hot springs during winter.
some info: (scientific paper) http://etd.fcla.edu/UF/UFE0013069/clifton_k.pdf
(easily-read fact sheet) https://oceantoday.noaa.gov/manatees101/
animal skeleton, manatee science
another interesting thing is that their rib bones have no bone marrow! weird! that's another factor in why they're so dense, and ALSO part of why their bones are weak.
https://awoo.space/media/i0mKA0lr32xNXNhJqt8
image sources
skeleton diagram source: https://activerain.com/blogsview/2455870/all-about-manatees
skeleton image: https://www.sciencesource.com/archive/Florida-Manatee-Skeleton-SS2564135.html