In the undersea world of the Plainfin Midshipman, a fish common along the Pacific Coast, bigger is not necessarily better. Yes, the larger males can produce a humming sound that attracts mates to their nests, but these males must then tend the eggs that their female acquaintances leave behind. It's a round-the-clock job with no breaks for dinner, and the caretakers are often emaciated when the eggs finally hatch.
Contrast that life with the one enjoyed by smaller midshipman males, which cannot produce mating calls but still manage to sire fishes. That's because their size allows them to pose as females and visit the nests of larger males. Oftentimes these nests already contain eggs -- the more, the merrier -- which the smaller males dutifully douse with their own sperm.
Another method of surreptitious fertilization is for a smaller midshipman male to release its milt in an area adjacent to an egg-laden nest and fan the liquid in that direction. Like the first method, it favors the smaller fish by leaving the hard work of being a parent to the unsuspecting hummer.
Click here to learn more about the Plainfin Midshipman.