Today, turtles often begin the sex act in open waters, sinking during copulation.

MSN: Fossilized turtles' sex act frozen in time - Technology & science - Science - LiveScience | NBC News

And the force used must be in addition to that which is used to commit the sex act.

FORBES: An Invitation for Elizabeth Warren: Talk About Defective Rape Laws

Paterson was convicted of performing a sex act on one of the young men and sexually assaulting both of them.

BBC: John Paterson abused sleeping guests in Glasgow home