【英语时差8,16】蜗牛2

（单词翻译）

Now here’s the strange part. About once a week, as garden snails² share caresses³, pressure builds up in the area surrounding a sac near the genital region housing a calcium⁴ dart⁵. Just for the moment of sexual penetration⁶, the impregnating snail¹ stabs its partner near the genitals with what scientists have dubbed⁷ the snail love dart. But what might sound like a nasty sadomasochistic ritual does have a practical purpose. According to one study, the darts⁸ are tipped with a chemical preventing the snail on the receiving end from digesting most of its mate’s sperm⁹. As in many species, the garden snail’s female reproductive tract¹⁰ is hostile to sperm, allowing only the toughest and most resilient to fertilize¹¹ the egg. To increase its chances of passing on its genes¹², the impregnating snail fires a dart to give its sperm a fighting chance.