Navigation Links
Male snails babysit for other dads

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 they might face if left on a stationary rock.

A male's shell may become covered in dozens of capsules, each containing up to 250 eggs. As the eggs hatch, a process that takes about a month, some of the baby snails devour the rest of their littermates. Typically only a handful of hatchlings survives the fratricide to emerge from a capsule and crawl away.

Kamel carried out DNA analysis of brood capsules to determine the eggs' parentage. On average, she found that the male snails had sired just 24 percent of the offspring on their backs. Many had sired far less.

"The promiscuity in the female snails is extraordinary," Kamel said, noting that some females mate with as many as a dozen different males.

Why do they do it? Typically in the animal kingdom, females invest more resources in an egg than a male does in a sperm, so mothers have a stronger interest in providing parental care. Males may mate with multiple partners to increase their chances of siring offspring, but typically make less investment in caring for those young. When dads do get involved, it's nearly always because they are assured that all or most of the offspring are their own. Male sea horses, for example, carry developing young in a pouch but all are their own genetic offspring.

One explanation could be that caring for the kids just doesn't cost the male snails much. But by tethering individual snails to a post sunk in the sand, Grosberg was able to follow them over time and show that the capsules do impose a significant burden, reflected in weight loss.

It may be that carrying the egg capsules simply represents the best of limited options for the males, Grosberg said, since it's impossible for them to mate without the female attaching an egg capsule to their backs.

Or carrying egg capsules may be a way for a male to show a female that he's good parent material.

"If he wants to get any action, he has to pay the price," Grosberg said.

Grosberg is fascinated by the conflicts that occur between parents, between siblings, and between parents and offspring as they each try to get resources and maximize their success in breeding. You can see these conflicts and rivalries all the way from simple animals to humans, he notes.

"Everything that intrigues me about family life happens in these snails," he said.

At the same time, no animal has gone as far as humans in evolving increasing cooperation between relatives, tribes and larger and larger (and less closely related) groups over time.

"We're good at seeing other forms of reward," Grosberg said.

Contact: Andy Fell
University of California - Davis

Related biology news :

1. Grazing snails rule the waves
2. The Quarterly Review of Biology: Why some fats are worse than others
3. Study proves that 1 extinction leads to another
4. Scientists uncover strategy able to dramatically reduce chemotherapys side effects
5. Infants of overweight mothers grow more slowly
6. Flightless molecule may prevent cancer from spreading from 1 tissue to another
7. New biomarker for common lung cancer predicts responses to chemotherapy
8. Rise in temperatures and CO2 follow each other closely in climate change
9. Environmental concerns increasing infectious disease in amphibians, other animals
10. First ever videos of snow leopard mother and cubs in dens recorded in Mongolia
11. Giving ancient life another chance to evolve
Post Your Comments:
Related Image:
Male snails babysit for other dads
(Date:4/15/2016)... 2016 Research and Markets has ... Market 2016-2020,"  report to their offering.  , ... ,The global gait biometrics market is expected to ... period 2016-2020. Gait analysis generates multiple ... used to compute factors that are not or ...
(Date:4/13/2016)... , April 13, 2016  IMPOWER physicians supporting Medicaid ... setting a new clinical standard in telehealth thanks to ... leveraging the higi platform, IMPOWER patients can routinely track ... and body mass index, and, when they opt in, ... convenient visit to a local retail location at no ...
(Date:3/31/2016)... R.I. , March 31, 2016  Genomics firm ... of founding CEO, Barrett Bready , M.D., who ... members of the original technical leadership team, including Chief ... President of Product Development, Steve Nurnberg and Vice President ... returned to the company. Dr. Bready served ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... ... June 27, 2016 , ... ... Amgen, will join the faculty of the University of North Carolina Kenan-Flagler ... of strategy and entrepreneurship at UNC Kenan-Flagler, with a focus on the school’s ...
(Date:6/24/2016)... 24, 2016  Regular discussions on a range of subjects ... the two entities said Poloz. Speaking at a ... , he pointed to the country,s inflation target, which ... "In certain areas ... have common economic goals, why not sit down and address ...
(Date:6/24/2016)... ... ... Researchers at the Universita Politecnica delle Marche in Ancona combed medical journal articles ... findings are the subject of a new article on the Surviving Mesothelioma website. ... blood, lung fluid or tissue of mesothelioma patients that can help point doctors to ...
(Date:6/23/2016)... June 23, 2016   Boston Biomedical , ... compounds designed to target cancer stemness pathways, announced ... granted Orphan Drug Designation from the U.S. Food ... gastric cancer, including gastroesophageal junction (GEJ) cancer. Napabucasin ... to inhibit cancer stemness pathways by targeting STAT3, ...
Breaking Biology Technology: