To kill it, use 2 tranq arrows(I only use tranqs for underwater tames.). It will die quickly. There is a rule saying I'm not allowed to ask for an update. LOOPHOLE. Submit a tip saying my knowledge. Tell my story, I am AnonymousUserYT.
Don't attack it with any sort of weapon, even stone. It will electrocute you. If you need its bio toxin, just attack it with fists, and make sure to stay far enough away so that it doesn't sting you. I suggest finding a group of these guys near the surface so that you don't have to worry about bringing any tames, or looking out for aggressive dinos. Hope this helps :>
Almost lost my lvl 700 rock drake to these things, I died 3 times trying to save it. Luckily my drake has 80,000 health and luckily an admin was online so the admin saved me. Those things did 22,000 damage to my drake in just a couple minutes. They are way too overpowered only one of them doing around 50 damage every half second and plus they are normally in a group of five which makes is worse. I'm never going in the ocean again.