"Similar to marine turtles, its limbs are paddle-shaped, but still possess movable digits," said Prof Eisemberg.

Swimming upright, it navigates by moving two body-length rows of thin, paddle-shaped protrusions that cascade like dominoes.

Then, with incredible gentleness for such an enormous creature, the larger manatee nudged the little one with her paddle-shaped flipper and pushed it to the surface beside me.