How do fish and birds hang together? The answer is a wake with purpose

Source: Science Daily

Fish and birds are able to move in groups, without separating or colliding, due to a newly discovered dynamic: the followers interact with the wake left behind by the leaders. The finding offers new insights into animal locomotion and points to potential ways to harness energy from natural resources.

https://www.sciencedaily.com/releases/2019/01/190128161517.htm