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August 10, 2022

What Weddell Seal Moms Sacrifice

What makes Weddell seals such excellent divers, routinely able to forage underwater for food as long as 20 minutes at a time? Did you know they have natural, internal scuba tanks? Weddell seal moms make an extraordinary sacrifice to help prepare their offspring for such extended underwater dives. But how? And could climate change play a role, putting mothers nursing seal pups at great risk? Learn more on NSF's "The Discovery Files."

Credit: National Science Foundation

What Weddell Seal Moms Sacrifice

This is The Discovery Files, from the U.S. National Science Foundation.

Mothers are known to make extraordinary sacrifices for their offspring. Weddell seal moms are no different! During lactation, they relinquish their own needs, to provide their young pups with the enormous amounts of iron they need.

Their bodies demand iron for their muscles and red blood cells to carry oxygen. These cells function like a natural internal scuba tank, storing oxygen and allowing the seal to make extended underwater dives.

With support in part from NSF, researchers at Woods Hole Oceanographic Institution, Texas Tech University, the University of Alaska Anchorage, and UC Santa Cruz studied how the Weddell seal moms nurse their pups.

They learned the mothers are sacrificing their own iron supply and the ability to store oxygen, resulting in a decline in the duration of foraging dives by post-partum females.

They were surprised to see that, although foraging dives were the shortest in the late Summer, Weddell seal moms gained weight, likely due to more nutritious, iron-rich fish, being available in the summer.

The team cautioned climate change could impact the availability of such nutritious prey and noted their research could improve seal conservation efforts, increasing understanding of the importance of specific prey at certain times of the year.

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