Image of the Day: Self-Insemination
Image of the Day: Self-Insemination

Image of the Day: Self-Insemination

Videos reveal how a female squid fertilizes her eggs—one at a time and without spilling much stored sperm.

Feb 1, 2019
Carolyn Wilke

ABOVE: Spawning Japanese pygmy squid attaching eggs to a blade of seagrass
EIJI FUJIWARA

Reproductive biologists can have a hard time figuring out how sperm reach eggs when females of some species store the sperm for later use. Now, researchers have caught a female Japanese pygmy squid (Idiosepius paradoxus) in the act. The squid inseminates her eggs one at a time using very little sperm. She cradles an egg in the arm crown from which her arms extend and attaches the egg to a surface, such as seagrass, then fertilizes it by placing her sperm-storage organ over it. The scientists published their observations in Current Biology on January 21. 

EIJI FUJIWARA
EIJI FUJIWARA

Y. Iwata et al., “How female squid inseminate their eggs with stored sperm,” Current Biology, doi:10.1016/j.cub.2018.12.010, 2019.