Bucketbill

The Bucketbill is an aquatic species appearing in Pikmin Z. It has a rounded body with a flipper on its tail for it to swim, and a set of small wings. The most prominent feature of this animal is its huge, elongated bill, which expands into a scooping net when striking prey.

Biology
This bird-like creature spends its time on the water surface. When it senses prey underneath it, it will strike down with its long neck and large bill, scooping up whatever prey is left underneath it.
 * Diet: fish
 * Predators: unknown

Piklopedia entry

 * "It looks like this creature almost defies the means of gravity in order to get these kinds of features: an extremely long neck with a bill just as long to secure whatever prey items swim underneath it. Surprisingly effective since it swims rather slowly."

Strategy
Make sure to avoid swimming underneath it. If it can't be avoided, dive down or swim aside before it can strike.