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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How tuna stay warm with cold hearts

Date:

February 5, 2015

Source:

Manchester University

Summary:

Scientists have discovered how prized bluefin tuna keep their hearts pumping during temperature changes that would stop a human heart. The research helps to answer important questions about how animals react to rapid temperature changes, knowledge that's becoming more essential as the earth warms. Pacific bluefin tuna are top predators renowned for their epic migrations across the Pacific Ocean. They are also unique amongst bony fish as they are warm bodied (endothermic) and are capable of elevating their core body temperature up to 20°C above that of the surrounding water. They are also capable of diving down below 1000 m into much colder water which affects the temperature of their heart.

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Tuna hearts 'affected by oil spill'

By Jonathan Amos

Science correspondent, BBC News, Chicago

Scientists say that tuna swimming in the Gulf of Mexico during the Deepwater Horizon oil spill may have experienced heart damage.

Lab research has demonstrated how crude oil chemicals can disrupt heart function in the fish.

The study, published in Science magazine, is part of the ongoing work to try to understand the impacts of the disaster.

The gulf is an important spawning ground for bluefin and yellowfin tuna.

Tracking studies have indicated that many of these fish would have been in the area during the 2010 disaster.

Scientists have long known that certain chemicals in crude oil – such as polyaromatic hydrocarbons (PAHs) – can be harmful to the hearts of embryonic and developing fish.

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