June 6, 2013 9:29 am
For females of some species, sperm is not only a means to achieve reproduction, but also a nutritious snack.
Bottletail squid, for instance, practice external fertilization; females store the sperm in a special cavity near their mouth until it’s time for fertilization. Some early evidence suggested females may be sneaking some of the sperm sacks as snacks, but the authors of a new paper, published in the journal Biology Letters, wanted to confirm that hunch. They radio-labeled spermatophores of male squids so they could track what happened to those cells once the males handed them over to the females.
The observations were telling. All six of the females that mated with radio-labeled males gulped down a few of the spermatophores—”a nourishing food source for a manipulative mate,” the authors write.
In other words, the females are slurping down sperm not necessarily because it’s delicious, but because it gives their future offspring a helpful nutritious boost. Females may even be eating sperm from unattractive males and fertilizing their eggs with sperm from their favorite mates, the authors suggest.
This sperm-eating behavior does make the bottletail squid a bit unique among species, according to Discover:
Sperm consumption — as opposed to just ejaculate swallowing — in the animal kingdom “is far less common,” according to Wegener. Species that exhibit this include carrion flies, picture wing flies, a strange marine invertebrate known as Spadella cephaloptera, a type of leech, a marine nudibranch and the southern bottletail squid Sepiadarium austrinum.
For males of these species, this isn’t great news. They spend energy to make and distribute that sperm, and they’re providing it to females with the intent of fathering the next generation, not handing out power shakes. However, the authors suspect that the male squid likely have a few counter strategies of their own—perhaps strategically placing sperm in parts of the female’s storage sack that are most difficult to reach or by targeting those females that are on the brink of laying eggs.
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