6 Strangest Hearts in the Animal Kingdom

by Laura Geggel, Staff Writer | February 13, 2015 08:47am ET

Hearts have become iconic symbols of Valentine's Day, but when it comes to hearts in the real world, one size doesn't fit all — particularly in the animal kingdom. The human heart beats about 72 times a minute, but in that same time, a hibernating groundhog's heart beats just five times and a hummingbird's heart reaches 1,260 beats per minute during flight. The human heart weighs about 0.6 pounds (0.3 kilograms), but a giraffe's weighs about 26 pounds (12 kg), since the organ needs to be powerful enough to pump blood up the animal's long neck. Here are some other creatures with strange hearts.

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Biological Mechanism for Growing Massive Animal Weapons, Ornaments Discovered

ScienceDaily (July 26, 2012) — In the animal kingdom, huge weapons such as elk antlers or ornaments like peacock feathers are sexy. Their extreme size attracts potential mates and warns away lesser rivals.

Now researchers led by scientists at the University of Montana and Washington State University have discovered a developmental mechanism they think may be responsible for the excessive growth of threatening horns or come-hither tail feathers. Published in the July 26 online edition of Science, the research reveals a mechanism to explain both the size of these traits, and the incredible variation among males of the same species -- why some beetles, for instance, grow massive horns while their fellows grow nothing but nubbins.

"Our research explains how these enormous traits get to be so enormous," said Doug Emlen, a professor and evolutionary biologist in UM's Division of Biological Sciences. "People have known for 100 years that the best males produce the biggest structures, but nobody has really understood how. Our work looks under the hood to explain why so many sexually selected structures get so massive."

Continued:  http://www.sciencedaily.com/releases/2012/07/120726142202.htm