The Amazing Physical Abilities of Dragonflies and Fleas [Reading Science]

Dragonflies flap their wings about 40 times per second and flap their wings millions of times a day, but their wings do not get damaged.
[Photo by YouTube screen capture]

[Asia Economy Reporter Kim Jong-hwa] Some insects exhibit incredible movements that are hard for humans to comprehend with common sense. Representative insects are dragonflies and fleas.

Dragonflies flap their wings about 40 times per second. They are said to fly all day long except for brief rests. Assuming they flap their wings for 24 hours, 1,440 minutes, or 86,400 seconds a day, it calculates to a staggering 3,456,000 wing beats per day.

Even if they do not fly for the entire 24 hours, they still flap their wings millions of times a day. However, if you catch a dragonfly and touch its wings, they look so thin and fragile that they seem like they would break easily.

It is amazing that these delicate wings can flap millions of times a day without breaking. How many times can a person wave their arms up and down in a day? Wouldn't they get tired or their muscles get damaged after just a few hundred times?

Fleas are very small insects, about 2 to 4 mm in body length. They often appear as protagonists in proverbs that describe something small. For a very shameless person, there is a saying, "Even a flea has a face," to scold them, and when a greedy person tries to take from a poor person, the proverb "to eat a flea's liver" is used.

Among these, the highlight is the proverb "Even if you jump, you are just a flea." This means that even if someone tries to run away, they cannot get far, implying that the person fleeing can be easily caught.

However, this proverb seems to underestimate the flea. A flea can jump up to 20 cm high and 35 cm far in one leap, which is more than 100 times its body length. While this may seem like a very short distance to a person, it is a very long distance for a flea.

To put it in human terms, it means jumping 100 times one's height, which translates to about 200 meters in one leap. This means a flea could jump over two or three multi-story buildings in a single bound.

The image shows a flea jumping, photographed by Professor Malcolm Burrow and Dr. Gregory Sutton from the University of Cambridge, UK.
[Photo by University of Cambridge, UK]

In the case of the dragonfly, it flaps its wings to the point where the wings could be damaged, and in the case of the flea, it jumps so hard that the muscles in its hind legs could burst. Why are insects able to use their bodies so recklessly and still remain lively?

Scientists say the secret lies in a protein called "resilin." Resilin is a type of rubber protein and is known to be the most elastic material discovered so far. Its elasticity is 3 to 4 times that of rubber, and even when stretched 3 to 4 times, its structure does not change, and when returning to its original state, it returns about 97% of the energy.

This means that when a dragonfly flaps its wings, only about 3% of the energy is consumed, and when a flea jumps once, only about 3% of the energy is used. In dragonflies, resilin is located where the body and wings connect, and in fleas, it is found in the leg muscles, allowing them to flap their wings and jump high throughout their lives without any problems.

Scientists are working to utilize resilin to develop spacesuits that can withstand high gravity and medical devices that can assist the human body. So, the saying "Even if you jump, you are just a flea" should not be used carelessly, right?