Spider hearts may contract in a unique double beat. By placing tarantulas in a magnetic resonance imaging scanner, biologists from Edinburgh University made a – video of a living spider's beating heart.

"In the videos you can see the blood flowing through the heart and tantalizingly it looks as though there might be 'double beating' occurring; a distinct type of contraction which has never been considered before," said Gavin Merrifield in a press release. Merrifield presented the research at the Society for Experimental Biology Annual Conference in Glasgow last month.

Merrifield and his colleagues used special MRI scanners, built for medical research on rats and mice, at the Glasgow Experimental MRI center, to measure heart rate and cardiac output in tarantulas. Most MRI technology is used purely for medicine, but it could branch out into new areas of biology.

"On the more academic side of things if we can link MRI brain scans with a spider's behavior, and combine this with similar data from vertebrates, we may clarify how intelligence evolved," Merrifield said.

Images: Gavin Merrifield