When getting to the finish line matters most, sometimes sperm cooperate to make sure the winning guy is from their swim team. Rachel Roth takes a dive into sperm cooperation and sperm altruism in the animal world.
SPERM COMPETITION IS CRAZY. Here are my notes from this episode on sperm cooperation.
Mini Mouse Swim Teams
Ref: Fisher, Giomi, Hoekstra & Mahadevan. 2014. The dynamics of sperm cooperation in a competitive environment. http://dx.doi.org/10.1101/006890
This team found the "optimal" number of sperm in a cluster. The aggregate in (f) is the optimal team size, and you can see why something like (g) with 13 sperm can be a biiiiiit less effective in the race to the egg. Bad group project mojo.
Ref: Competition drives cooperation among closely related sperm of deer mice, Heidi S. Fisher& Hopi E. Hoekstra
The video above is from Heidi S. Fisher's "Competition drives cooperation among closely related sperm of deer mice" study in 2010. These are the cooperative deer mice sperm swimming together!!!
Ref: This National Geographic article by Ed Yong in 2014 was a very helpful read for these studies: These Mice Excel At Assembling The Ideal Sperm Swim Teams
Giant Swim Teams: Wood Mouse
Ref - Exceptional sperm cooperation in the wood mouse Harry Moore, Katerina Dvoráková, Nicholas Jenkins & William Breed (Nature 2002)
Last but not least: LET'S TALK ABOUT ANTS!
Desert Ant: the true #vikinglongsperm
Behold the Desert Ant, whose #vikinglongsperm cooperate to fill the queen's spermatheca. Nature is wild.
Here's another report on the same study: https://www.newstatesman.com/sci-tech/2014/06/study-finds-ant-sperm-get-ahead-through-synchronised-swimming
I also BRIEFLY mentioned diving beetles in the episode, but the more interesting implications have to do with the evolution of the female genital tract and how she controls reproduction in the face of awful male tactics, so... Probably a deep dive for another time. Here's a dope diving beetle sex article if you're itching for more right now, though.