Science Friday

Sperm Swim Together To Help Each Other Reach The Egg

New research is complicating our understanding of how, exactly, sperm are able to reach eggs. The predominant theory is that sperm compete against each other, with the strongest swimmer fertilizing the egg.

But a new study, using cow sperm, suggests that sperm might actually swim together, forming clusters to help each other swim upstream to reach the egg.

Researchers created a device that has some of the features of a female reproductive tract, which they tested using a polymer substance that mimics cervical mucus. The intensity of the flow of this mucus-like fluid influenced how well the sperm clustered together. The faster the flow, the more likely the sperm were to band together to swim upstream.

Ira talks with Dr. Chih-Kuan Tung, associate professor of physics at North Carolina Agricultural and Technical State University about his research on sperm motility, and how it could improve infertility testing in the future.

When you hear the word ‘rover,’ it’s likely your brain imagines another planet. Take Mars, for instance, where the steadfast rolling science labs of Perseverance and Curiosity—and the half dozen robotic rovers before them—slowly examine the geology of the Red Planet for signs of past habitability.

But Earth has rovers too. The autonomous, deep-sea Benthic Rover II, engineered by researchers at the Monterey Bay Aquarium Research Institute (MBARI), trawls a desolate surface too—this one 4,000 meters below the surface of the ocean, on a cold abyssal plain, under the crushing weight of 6,000 pounds per square inch of pressure.

Deep beneath the surface, the rover is seeking data about carbon: What carbon sources make it down to such a deep sea floor? And does that carbon return to the atmosphere as carbon dioxide, where it might contribute to global warming, or sequestered safely as an inert part of the ocean sediment?

Ira Flatow talks to engineer Alana Sherman and ecologist Crissy Hufford, both of MBARI, about the work it takes to make a rover for the deep sea, and the value of its data as we look to the future of our oceans.

Igor Klymenko is a 17-year-old inventor from Ukraine, and he recently won the Chegg.org Global Student Prize—a $100,000 award given to a young change-maker. Klymenko won it for his invention, the Quadcopter Mines Detector, which is designed to locate underground landmines. The issue of unexploded landmines cannot be understated—some estimates show there could be about 100 million of them scattered across the globe.

Klymenko is a student at both the University of Alberta in Canada and the Igor Sikorsky Kyiv Polytechnic Institute in Ukraine. He joins Ira this week to talk about the Quadcopter Mines Detector, and how he’s trying to help his home country, Ukraine, through engineering.

If you’re looking for a new sport or hobby to try, forget about rock climbing or kitesurfing. If you don’t mind getting a bit dirty, consider competitive soil judging—a contest in which contestants work to best analyze, identify, and describe the layers of soil in a 5-foot-deep trench dug into a field. People can compete either individually, or in a team format, where different members of the team work to describe the soil’s characteristics—from color, to grain size, to how it interacts with water.

Clare Tallamy, a senior at Virginia Tech majoring in environmental science, recently won the individual competition in an international soil judging contest held in Scotland as part of the 2022 World Congress of Soil Science. She joins Ira to describe how soil judging works, gives an introduction to soil taxonomy, and explains the practical significance of being able to excel at judging a sample of soil.

Transcripts for each segment will be available the week after the show airs on sciencefriday.com.