Scientists have discovered an aggressive defensive measure used by male blue-lined octopuses to avoid being eaten by females after mating. Unlike female black widows and praying mantises, which are known for consuming their mates post-coitus, males bite the larger females and inject them with a potent neurotoxin called tetrodotoxin, paralyzing them in the process.
The venom, also found in pufferfish, is administered near the aorta, rendering the female octopus immobile. However, the researchers found that despite being several times larger than males, the females displayed a resistance to the toxin, allowing them to regain control of their arms and escape after a short period.
Source: https://www.newser.com/story/365538/male-blue-lined-octopuses-use-venomous-mating-strategy.html