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Black Widow Siblicide

September 27, 2016

Female black widows derail their offspring’s attempts at siblicide.



Sibling spider snacks…I’m Bob Hirshon and this is Science Update.

Female black widow spiders are famous for occasionally eating their mates. But their babies cannibalize their little brothers and sisters as well.

CHAD JOHNSON (Arizona State University):

The nutritional value of their siblings has gotta be huge.


Now, Arizona State behavioral ecologist Chad Johnson and his team report in the journal Animal Behaviour that female black widows can rein in their offspring’s murderous tendencies. They found that eggs experimentally reared at warmer temperatures grew more quickly, gobbling up their smaller siblings after hatching. But in nature, the female works hard to synchronize her brood, so no one has an unfair advantage.


She seems to be doing an amazing job of provisioning them equally for her own benefit to try to minimize cannibalism.


The results could provide insights into how to better control black widow infestations. I’m Bob Hirshon, for AAAS, the science society.


Story by Susanne Bard