Manatee and Sea cow

Manatee noun - Sirenian mammal of tropical coastal waters of America; the flat tail is rounded.

Sea cow and manatee are semantically related. In some cases you can use "Sea cow" instead a noun "Manatee".

Sea cow noun - Any of two families of large herbivorous aquatic mammals with paddle-shaped tails and flipper-like forelimbs and no hind limbs.

Manatee and sea cow are semantically related. You can use "Manatee" instead a noun phrase "Sea cow".