# Has homosexual behavior ever been observed in invertebrates?

**URL:** <https://boards.straightdope.com/t/has-homosexual-behavior-ever-been-observed-in-invertebrates/681712>\
**Category:** Factual Questions\
**Created:** [February 19, 2014, 4:33pm UTC](https://boards.straightdope.com/t/has-homosexual-behavior-ever-been-observed-in-invertebrates/681712 "2014-02-19T16:33:07Z")\
**Posts on this page:** 1\
**Showing post:** 11

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**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\
**Post date:** [February 20, 2014, 10:40pm UTC](https://boards.straightdope.com/t/has-homosexual-behavior-ever-been-observed-in-invertebrates/681712/11 "2014-02-20T22:40:56Z")

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And then there’s penis fencing, practiced by some flatworms. The worms are hermaphroditic, but in any given mating, one will take on the female role, while the other takes on the male role. Both get the same benefit from this, offspring, but it costs the mother a lot more than it does the father. So how do they decide who gets to be the dad? By penis fencing. The flatworm penis has a sharp point, and they jab at each other until one penetrates the other’s skin and inseminates it.

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