The upper mandible has a tooth-like  protrusion that helps them grab prey.

上颌骨有一个牙齿状的突起，可以帮助它们抓住猎物。

In this latter bird the lamellae of the upper mandible are much coarser than in the common duck, almost confluent, about twenty-seven in number on each side, and terminating upward in teeth-like knobs.

后一种鸟的上颌骨薄片比普通鸭粗糙得多，几乎汇合在一起， 每侧约有 27 个， 向上终止于牙齿状的突起。