Bats spawning underwater

I was exploring a shipwreck when I heard the sound of a bat. I then saw a bat floating around in the ship. It soon drowned (rip).

What I expected to happen was...:
There to be no bats because bats (obviously) aren't sea creatures.

What actually happened was...:
A bat spawned underwater.

Steps to Reproduce:
1. Go to a shipwreck.
2. See if there's a bat there.
3. Might not be though.