Pity the male of the marine whelk, Solenosteira macrospira. He does all the work of raising the young, from egg-laying to hatching even though few of the baby snails are his own.
The surprising new finding by researchers at the University of California, Davis, puts S. macrospira in a small club of reproductive outliers characterized by male-only child care. Throw in extensive promiscuity and sibling cannibalism, and the species has one of the most extreme life histories in the animal kingdom.
The family secrets of the snail, which lives in tidal mudflats off Baja California, are reported online in a study in the journal Ecology Letters.
In the study, UC Davis researchers report that, on average, only one in four of the hundreds of eggs that a male S. macrospira carries around on his back belong to him. Some carry the offspring of as many as 25 other males.
Such extreme cases provide the raw material on which natural selection can work and shed light on more "mainstream" species, said study author Rick Grosberg, a professor of evolution and ecology at UC Davis.
"It opens our eyes to viewing other kinds of behavior not as weird or harmful but as normal," he said.
The snails were first described in an amateur shell-collectors newsletter, The Festivus, in 1973. Grosberg started studying the animals in 1994, when he brought some back from a collecting trip and realized that only male snails had egg capsules on their shells.
When the snails mate, the female glues capsules containing hundreds of eggs each to the male's shell.
The male's shell likely acts as a substitute rock, since the snails' habitat offers few surfaces on which to glue eggs, said co-author Stephanie Kamel, a postdoctoral researcher in Grosberg's lab.
Moving in and out with the tide on dad's (or stepdad's) back also protects the egg capsules from the extremes of heat and drying t
|Contact: Andy Fell|
University of California - Davis