People claiming the otter is useless have never seen one go toe to toe with a megalodon and almost damn near win. It was on my shoulders when I died and it took me a while to find my stuff, but when I found it, the damn otter was still swimming around in circles, trying to beat up the massive shark that killed it's owner. It now has a tombstone made in loving memory.
A tribe mate once picked up a level 23 otter off the beach that belonged to another tribe and held it above an alpha megaladon, the shark jumps up and eats the otter then dies instantly from being out of the water. IGN 10/10
If you kill one, you will be hunted down by all the gigas and rexes and wyverns and everything deadly until you have started crying in real life from the regret of killing that little, innocent creature that just wanted a top hat.