On the Origin of Strangeness

Worse than Oedipus

15 August 2017

A creature fated to die before it is born. This paradox sounds like one of Gollum’s riddles, yet it is part of the real lifecycle for male mites belonging to a genus known as Adactylidium. Found mostly in the Middle East, these microscopic parasites feed on the eggs of a tiny insect called a thrip. After birth, the females venture out to find a new egg to feed on, while the males emerge from their mother only to die shortly after. They do not feed and they do not mate – they just wait for their demise. For decades, this strange characteristic puzzled zoologists, who wondered why the males existed if all they did was die.

Eventually, the bizarre life cycle of Adactylidium was revealed. A female Adactylidium mite is born already carrying several fertilised eggs. A few days later, the eggs hatch inside her, giving rise to several females and one male. Then, showing no regard for one of the strongest taboos in human society, the male mates with every one of his sisters – inside their mother. But fetal incest isn’t creepy enough for these mites: they proceed to eat their mother from the inside out, completing their gory lifecycle. In some species, the male joins the females in devouring their mother and exploring the outside world. In others, he is never born, dying in the womb as soon as his reproductive role is fulfilled. The entire process, from the female leaving her mother’s body, to being eaten herself, lasts about four days.

Sibling mating and matricidal cannibalism may be great concepts for a horror movie or in Game of Thrones, but is it beneficial when it’s found in nature? While matriphagy, or mother-eating, is reasonably common in some insects, scorpions and spiders (and you thought your mum made sacrifices for you), mating with siblings increases the risk of offspring inheriting recessive birth defects, which is probably why humans and many other animals are so averse to the practice. Adactylidium must have a pretty good reason to override this aversion.

As the Adactylidium mite feeds on only one thrip egg for its entire life, incest may be a reaction to the limited amount of resources it has available. Providing each of its children with a nearby suitor spares them the intensive effort of finding a mate. (Think about how exhausting it is finding a suitable date. Now imagine enduring all those fuckboys after only having a pea for breakfast.) However, the low ratio of males to females in the brood is risky – what if the single male dies, leaving his sisters unsuccessful (in evolutionary terms) virgins? Mating in-utero mitigates this risk, allowing their mother to protect them. Thanks Mum!

So next time someone mentions the Oedipus complex, or Cersei and Jaime Lannister, and you want some shock-value, just tell them about the Adactylidium mite. I can’t guarantee it will earn you social points, but it will grab their attention.

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