To tame:

Drop any looted equipment at maximum durability, easily obtained from slain megs/drops. It will eat the item and enter a rideable state, mount it. You'll sometimes be presented with an immediate feed prompt, other times you'll have to tire it out by simply matching the button prompts to stay on, until it gives you a feed prompt. After feeding you dismount automatically. wait 30 seconds before repeating. Eats "little raffish treats" an expensive kibble crafted from 6 honey, 8 tueso tentacles and 10 ammonite bile. The treats keep better than the ingredients so craft em up and keep them in a fridge until you find a high level heli. level 150 takes about 15. But on any weekend or holiday its 7.

Reccomend using sharks to get your ocean start, 10 level 20 sharks can litterally kill alpha mosasaur's as long as you cook them in a fridge for a day or two, and dump 40 points in their hp and craft saddles. (Dinos gain significant xp while in a cryo fridge) making the tueso tentacles and ammonite bile super easy to obtain. Honey is it's own misery, goodluck with your bees!

Reccomend bringing 6 behemoth gates during taming, they like to hang out in the shallows, and being a neutral temperament they wont attack you while you pen them in. Use dropped looted items to bait them into the pen if they're in deep water.

Utility:

Has a unique crafting stat that can be leveled via points, or mutations. A good 150 perfect tame will have about 35% on average, you can bump that to 47% with 60 points dumped in it, dicey to risk your best gear on, but you can place items in its inventory to craft blueprints from looted items. (Cannot be a crafted item) with breeding you can improve this crafting stat by 2% per mutation, each baby rolls a 0.5% chance to gain 2 levels to a random stat, slow going, but they're easy enough to breed.

Additionally, they function as a mobile smithy on the sea, and have an excellent thrash attack that deals very high torpor! For you pvp psychos you can dismount players off water tames, stunning the player and the tame for about 6 seconds.

Parting advice, the difficulty in obtaining and high level requirement to their saddle (91) make them very endgame, focus on getting sharks early game if you're doing an ocean start, and getting a grinder to craft flint for the xp. They are DEADLY if supported by a pack of megs!