Definition of "free-swimming"

It is a most remarkable fact that almost all these shore animals in their early development from the egg pass through free-swimming larval stages which are closely alike in form for very widely different zoological groups.

1885, Sir Norman Lockyer, Nature - Volume 32, page 418

The presence of free-swimming and stalked ciliates, some flagellates, and rotifers in mixed liquor indicates a balanced, properly settling environment.

2008, Frank R. Spellman, Handbook of Water and Wastewater Treatment Plant Operations, page 715