Can kill squid like their kin in real life. Tame a 150 and you can take on alphas like they are regular ones. Just up health and memes. They recover steam so quick boosting it is pointless. An all around amazing creature, 10/10.
I use my 170 basilosaurus to kill the alpha mosasaurus (level 50+) mine has 30k health. I bite until half health, rise all the way to the surface and continue until the mosa is dead. Health rises so fast at the surface!
This is the only sea mount you should currently use for adventuring or the underwater caves. High levels easily tear through alphas and other hard to kill creatures like squids or mosas without the fear of dismounting due to squids or eels or jellyfish.
Do not be almarmed by it taking damage in deep water, its very small and takes a long time to kill your whale and can easily be healed by surfacing. The underwater caves have pockets you can surface at to heal. The surface healing can out-heal almost all wild dino damage and a lot of the cave damage. Fight at the surface if you can.
They also generate oil over time. They can only carry 20 oil at a time though so make sure you empty it often. The oil also spoils so use it quickly.
You can also press left trigger at the surface to jump and spray water. Careful not to beach your whale in the process though.
Rare Flowers affect the Basilo (slightly inconsistently) allowing you to kite it into your own water pen for a super safe, even easier tame involving much less swimming about. Seems to require you to eat at least 2 flowers to trigger the aggro effect, and it loses aggro the second the effect ends.