Ankys won’t attacked unless provoked. They are not very fast, but can deal a lot of damage with their spiked tails. They are more than twice as fast in water.
They have high health for their size, which makes them useful as a tank, according to the gamepedia. Even so, it’s probably most useful as a harvester. With a few exceptions (fiber is one), the anky can harvest berries (with it’s bite attack), trees, rocks, metal, crystal, obsidian, and flint, and they carry raw metal at a 75% weight reduction.
An anky can harvest a rock golem to get a huge amount of resources.
Ankys can be carried by quetzals and argentavis.
It can be used to gather oil from the bottom of the sea if you level up its oxygen.
Since the anky can harvest almost any object in the game, it is a wonderful tame to use when clearing a large area.
Increasing the melee on the anky results in more resources gathered per swing.