– How do scientists know that a sea creature is extinct or endangered if they haven’t explored 80% of the sea?

Question

– How do scientists know that a sea creature is extinct or endangered if they haven’t explored 80% of the sea?

In: 2

Answer 1

We don’t. As an example we thought the Coelacanth went extinct millions of years ago until we found them off the coast of Africa.

https://en.m.wikipedia.org/wiki/Coelacanth