Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Penguins ingest mollusk shells to obtain calcium for thicker eggshells

11.05.2004


It is virtually impossible for a prospective Magellanic penguin mother to find or build a soft spot to lay her eggs. So it turns out that her eggs come with extra-thick shells to withstand being laid on hard surfaces and survive being kicked around during penguin fights.



But it takes a lot of extra calcium to produce thicker shells, and a penguin can’t just run to the corner drugstore to pick up some calcium-rich antacid tablets. New research led by a University of Washington biologist shows that during the period when eggs are being laid, female penguins have significantly more mollusk shells, mainly clams and mussels, in their stomachs than males do. The mollusk shells gradually leach calcium used to form eggshells.

Penguins typically nest on hard surfaces near coastlines and, if soil conditions are right, they might build burrows. Because they can’t fly and are made to be agile swimmers rather than to walk gracefully on land, it is rare that they can collect much soft nesting material.


Still, their eggs are rarely broken because the shells are more than 50 percent thicker than expected for their size, which is about twice that of a chicken egg, said Dee Boersma. The University of Washington biology professor has studied penguins in South America, Antarctica and various South Seas islands, and said the thick-shell pattern follows for some other birds too.

"The birds that lay eggs on rocks or those that tend to lay them from great heights, like ostriches and rheas, also tend of have thicker eggshells," she said.

Both female and male penguins typically fast for a week or more before eggs are laid. Both genders ingest mollusk shells before the fast begins, which could alleviate hunger during the fast. But females lacking other sources of calcium ingest significantly more mollusk shells, which apparently supplements calcium taken from their bones for eggshell formation.

The thicker shells are important for penguins, which often nest in large colonies. Boersma has documented that, particularly in more densely populated colonies, periodic nasty fights break out and eggs or newly hatched chicks are destroyed as the adults scurry back into their nests or burrows, either during or after a fight.

"There’s a point where you can’t build strong-enough eggshells to survive fights. If you could, the chicks probably couldn’t get out," she said. "Remarkably, they don’t lose that many."

Eggs also are lost when heavy rains saturate the ground and cause burrows to collapse, but even then the thicker eggshells prove to be advantageous, since adults are able to retrieve some of those eggs.

Boersma is the lead author of a paper documenting the penguin eggshell research published recently in The Auk, a quarterly journal of the American Ornithologists’ Union. Her co-authors are Ginger Rebstock, a UW research associate in biology, and David Stokes, an assistant professor of environmental studies at California’s Sonoma State University.

From 1984 through 2001, Boersma and her colleagues gathered data on 10,023 eggs at a Magellanic penguin reserve at Punta Tombo, Argentina. Just 257 of the eggs, or 2.6 percent, were broken by anything other than predators or human-caused accidents, similar to the rate for birds that do not nest on hard surfaces or fight in the vicinity of the nest. The researchers determined that 43 percent of the broken eggs were destroyed because of fights.

The researchers also performed necropsies and examined stomach contents of penguin carcasses collected at different times of the year. In the post-egg-laying period, few penguin stomachs contained mollusk shells and the findings were the same for male and female. But during the period around egg-laying, females were far more likely to have shells in their stomachs than males.

"Basically, they’re getting a slow-calcium release for weeks before they lay their eggs," Boersma said.


The research was supported by the Wildlife Conservation Society, the Exxon/Mobil Foundation, the MKCG Foundation, the W.K. Kellogg Foundation and Friends of the Penguins.

For more information, contact Boersma at 206-616-2185, 206-616-2791 or boersma@u.washington.edu; Rebstock at 206-616-4054 or gar@u.washington.edu; or Stokes at 707-664 2722 or david.stokes@sonoma.edu

Vince Stricherz | EurekAlert!
Further information:
http://www.washington.edu/

More articles from Ecology, The Environment and Conservation:

nachricht Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.

nachricht 100 % Organic Farming in Bhutan – a Realistic Target?
15.06.2018 | Humboldt-Universität zu Berlin

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Graphene assembled film shows higher thermal conductivity than graphite film

22.06.2018 | Materials Sciences

Fast rising bedrock below West Antarctica reveals an extremely fluid Earth mantle

22.06.2018 | Earth Sciences

Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View

22.06.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>