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Why the tiny fruit fly has giant sperm: Size matters to her

This image provided Romano Dallai, Italian National Academy of Entomology shows a scanning electron micrograph image of a fruit fly sperm, which when unraveled reaches about 2.3 inches long, 1,100 times bigger than human sperm. New research shows that the female fruit fly drove the evolutionary process that made the speck of a bug have sperm that is 23 times longer than its body. (Romano Dallai, Italian National Academy of Entomology via AP) This image provided Romano Dallai, Italian National Academy of Entomology shows a scanning electron micrograph image of a fruit fly sperm, which when unraveled reaches about 2.3 inches long, 1,100 times bigger than human sperm. New research shows that the female fruit fly drove the evolutionary process that made the speck of a bug have sperm that is 23 times longer than its body. (Romano Dallai, Italian National Academy of Entomology via AP)

By Associated Press May 25, 2016 3 min read

WASHINGTON (AP) – For a long time, the debate has gone on: Does size matter to females? Biologists now say, definitively, that it does.

Among fruit flies.

At issue is the fruit fly sperm, which is gargantuan in the tiny world of that speck-sized insect. How big? A fruit fly’s sperm is 2.3 inches long, or about 23 times longer than its body. It’s more than 1,100 times longer than human sperm. If a man had sperm the same proportion to its body as a fruit fly, it would be nearly 140 feet long.

This has been long known to scientists; they’ve also known that the sperm fits into the bug because it’s coiled tightly, like a ball of yarn.

But they wondered was why such a little bug has such big sperm.