A replica of the appendage creates bubbles that produce high pressures and temperatures
Some shrimp have a secret superpower: Snapping their claws unleashes bubbles that produce plasma and shock waves to stun prey. Now a 3-D printed replica claw has reproduced the phenomenon in the lab, scientists report March 15 in Science Advances.
When a snapping shrimp (Alpheus formosus and related species) slams its powerful claw shut, it spews a jet of water. That fast-moving stream creates a bubble, which then collapses on itself. The collapse produces extreme pressures and temperatures that reach thousands of degrees Celsius, generating a plasma, a state of matter in which electrons are freed from their atoms (SN: 10/6/01, p. 213).
Using scans of a snapping shrimp’s claw as a blueprint, scientists 3-D printed a version five times the size of the original, making it snap shut at about the same speed as the real thing. The team used high-speed imaging to observe the bubbles that the fake claw produced as well as another camera that picked up dim flashes of light associated with the plasma. The researchers are investigating whether similar techniques might be useful for disinfecting water with plasma, which can kill pathogens (SN: 3/4/17, p. 15).
But for the shrimp, the plasma production is an afterthought: “We don’t think the shrimp are intentionally trying to make a plasma,” says mechanical engineer David Staack of Texas A&M University in College Station, a coauthor of the study. Instead, the shrimp aim to produce a shock wave that immobilizes their prey. That shock wave occurs under conditions that also produce a plasma, Staack says. “It does go claw in hand.”
BUBBLE’S BIRTH A bubble forms when scientists operate their 3-D printed replica of a snapping shrimp’s claw, as shown in real time and in a high-speed video. The bubble oscillates in size as it collapses.
X. Tang and D. Staack. Bioinspired mechanical device generates plasma in water via cavitation. Science Advances. Published online March 15, 2019. doi:10.1126/sciadv.aau7765.
C. Martin. Cold plasma puts the chill on norovirus. Science News. Vol. 191, March 4, 2017, p. 15.
P. Weiss. Shrimps spew bubbles as hot as the sun. Science News. Vol. 160, October 6, 2001, p. 213.
S. Milius. Snapping shrimp whip up a riot of bubbles. Science News. Vol. 158, September 23, 2000, p. 199.