During World War II, Japanese researchers, led by Dr. Shiro Ishii, tested a new weapon on Chinese prisoners at the notorious Unit 731 facility. Referred to as maruta or “logs” (since local residents were told that Unit 731 was a lumber mill), the prisoners were staked out and “bombed” with canisters containing an ancient killer – fleas. Bubonic plague (commonly referred to as “The Black Death”) had once laid the Earth’s population to waste in a series of pandemics that killed up to 35 million people during what would become known as the Dark Ages.
Transmission of the plague to humans usually occurs after a person is bitten by a flea that has fed on the blood of a rodent infected with the bacteria Yersina pestis. Normally, a rat flea will only bite a human briefly and by accident but once the plague bacteria begin multiplying within it, the entrance to the flea’s stomach becomes blocked. This prevents the flea from obtaining nutrition - and results in a hunger that drives the insect to feed insatiably (and continually, since it cannot fill its stomach) on any warm-blooded creature nearby.
On a less morbid topic - for their size, fleas make the longest jumps of any animal on the planet - reaching a distance of up 200 times their body length. This would be the equivalent of a 6-foot man jumping 1200 feet! How do they do it? Flea jumps can be compared to the mechanics of an archery bow. Fleas use their muscles to store potential energy in a flexible, skeletal protein called resilin - the most efficient elastic protein in all of nature. When a flea wants to jump, its exoskeleton releases the stored energy (like an archer releasing an arrow) – and off the flea goes – onto your dog. Not surprisingly, resilin is currently being investigated by the sneaker industry.