Irony of phallus dentatum:
Rather than the sleek, smooth tadpoles that other mammals have, the mole rat’s sperm had all manner of abnormally shaped heads. Some are squashed, others long. Some have bulbous lobes all over them. There are sperm with shrunken heads, two heads, conical heads. The DNA inside them isn’t packaged properly. Most are asymmetrical. And all the males – whether breeding or not – had the same misshapen sperm.
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With all these deviations, it’s no surprise that the naked mole rat’s sperm won’t be winning any races. Only between 1 and 15 percent of them can actually swim, and just 1 percent of these can swim quickly. The vast majority move at a slow crawl; they might even be the slowest sperm of any mammal.
