A Single Drop of Blood is Said to Attract Sharks. YouTuber's Experiment Shows There's More to it
Creature features such as "Jaws" and "Deep Blue Sea," have instilled fear of sharks in the public psyche. Former NASA engineer turned YouTuber Mark Rober wanted to test the validity of this widespread belief and carried out an experiment in the ocean with a large population of sharks. He shared his experience on social media, and the results were not quite what people expected.
In July 2019, he located a spot 20 miles off the coast of the Bahamas, which was populated by sharks. He collaborated with marine biologist and shark diving expert Luke Tipple for the task. The former NASA scientist wanted to test out this theory for a long time and started the video expressing his excitement. In order to conduct the experiment smoothly, he used 'NASA-grade hardware' and got help from Discovery.
The aim of the exercise was to see whether sharks were attracted to a single drop of blood, and how far or near they needed to be for their senses to be triggered. But before that, Rober found it necessary to understand, whether there was any preference for blood among Sharks. If other fluids are placed in front of these beings, what will they choose was a question he wanted answered. He explained: "I planned to test just how far they could smell a single drop of blood in the water, but first, I wanted proof that they actually preferred blood over any other scent." Four surfboards were rigged to pump out two liters of a different liquid - fish oil, cow's blood, seawater, and urine. For an hour they were pumped into the ocean. Mark and Luke used drones to monitor movement around the liquid. "Each surfboard has a waterproof receiver box that also holds the battery, a custom printed circuit board, and two Arduinos," the researcher said. "Then I have the remote control and as soon as I hit this button, they all start pumping at the same time."
For the first 10 minutes, there was no activity implying that blood did not affect the senses of sharks. After 20 minutes, sharks began to arrive and made their way to different boards. Four sharks came near fish oil, there was nothing around seawater or urine, but the blood board had a direct visit from a whopping 41 sharks. Mark concluded, "Now that we've debunked some surfing myths about urine and proved that sharks certainly have a strong preference for blood over anything we tested, the real question is, just how much blood is interesting to them?"
For the next phase of the experiment, Mark decided to use human blood. He took blood from himself and other crew members to get the whole thing going. Four bulging bags were connected to two boards and put into the ocean. "The board on the left would pump the human blood slowly at one drop a minute, the right would pump the blood fast, on average one drop every four seconds," Mark explained. For an hour none of the sharks checked the site. "This was by no means a perfect experiment, but I think it's safe to qualitatively say that if no sharks came to check out 15 drops of human blood a minute, in the middle of shark-infested waters, you're probably going to be OK with a small scrape," Mark shared.