A STRANGE LIFE CYCLE OF EITHER 13 OR 17 YEARS!
The cicada’s claim to fame is its singing. The high-pitched song is actually a mating call belted out by males. Each species has its own distinctive song that only attracts females of its own kind. This allows several different species to coexist.
They are the only insects capable of producing such a unique and loud sound. Some larger species can produce a call in excess of 120 decibels at close range. This is approaching the pain threshold of the human ear! Smaller species sing in such a high pitch that it cannot be heard by humans, but may cause dogs and other animals to howl in pain.
The apparatus used by cicadas for singing is complex. The organs that produce sound are called tymbals. Tymbals are a pair of ribbed membranes at the base of the abdomen. The cicada sings by contracting the internal tymbal muscles. This causes the membranes to buckle inward, producing a distinct sound. When these muscles relax, the tymbals pop back to their original position. Scientists still don’t fully understand how this apparatus produces such extreme volume.
Cicadas usually sing during the heat of the day. In addition to attracting a mate, the loud noise actually repels birds. The cicada’s song is painful to the birds’ ears and interferes with their communication, making it difficult for the birds to hunt in groups. Male cicadas in the same brood will stick together when calling in order to increase the total volume of noise. This reduces the chances of bird predation for the whole brood.To us as humans any sound above 85 dB can cause hearing loss, and the loss is related both to the power of the sound as well as the length of exposure. You know that you are listening to an 85-dB sound if you have to raise your voice to be heard by somebody else. Eight hours of 90-dB sound can cause damage to your ears; any exposure to 140-dB sound causes immediate damage (and causes actual pain).
Even cicadas must protect themselves from the volume of their own singing. Both male and female cicadas have a pair of large, mirror-like membranes called the tympana, which function as ears. The tympana are connected to an auditory organ by a short tendon. When a male sings, the tendon retracts, creasing the tympana so that it won’t be damaged by the sound.
they have no chewing mouthparts, and they feed (drink, really) more like aphids. Adult and nymphal cicadas feed on plant sap called xylem – the watery part of the plant sap – which they suck up through their proboscis (feeding tube). Feeding by periodical cicadas does not seem to affect trees and shrubs very much because they take only a small fraction of the water passing through. About 5 billion of them, scientists estimate—the very rough equivalent of Earth’s total human population in just a few hundred square miles. It is one of the most unique and mysterious phenomena in the natural world, and nothing can stop it.
The genetic mechanism that prompts periodical cicadas to emerge kicks in every 17 years (or every 13 years for other broods) when the ground warms up to 64°F (18°C).Some researchers think the timing of a brood’s emergence is a defensive mechanism—appearing at infrequent intervals means that it’s harder for would-be predators like birds and squirrels to anticipate when the insects will be available to eat. predators don’t necessarily wait for the females to lay their eggs. As soon as the cicadas emerge, many animals gorge on them, including foxes, skunks, raccoon, squirrels, chipmunks, dogs, cats, birds, snakes, spiders, and other opportunistic feeders — even humans. (For cicada recipes, events, and other fun cicada links. But the cicadas, having all emerged at once, are so numerous that predators can’t possibly eat enough to put a dent in the population. It’s a survival strategy called “predator satiation.”
Others suggest that the 13- and 17-year cycles, prime numbers in mathematics, help cicadas avoid parasites. A 2004 study from the University of Campinas in Brazil suggested that a cicada with a 17-year cycle and a parasite with a two-year cycle, for example, would meet only twice each century.
They move up into the trees. When they invade a tree, the females will cut slits into small branches to deposit eggs. These small branches will probably die, but the tree will survive up to 40,000 can emerge from under a single tree within days. Their subterranean tenures are intriguing not only because 13 and 17 years are long periods over which to remain synchronized, but also because both numbers are prime — divisible only by themselves and the number 1.A leading theory is that long, prime-numbered life cycles minimize the likelihood that the 13-year broods and 17-year broods will ever mate. If the animals lived smaller prime-numbered lives, like 5 and 7, they’d synch up every 35 years; if their lifespans were large, non-prime numbers, like 12 and 16 years, they might inadvertently mate every 48 years. But the large prime numbers 13 and 17 only match up every 221 years.Normally, periodic cicadas spend their lives in complete darkness underground, sucking the fluid out of the roots of trees and shrubs. At the end of their life, they emerge, breed, and almost instantly die, completing a life cycle that humans have studied for centuries The good news is that they do almost no harm. They don’t sting or bite. Nor do they eat crops, as do the grasshopper locusts with which they are often confused. They just want to dance, to mate. And they bring their own music, a monstrous rattling chorus that, in wooded areas, will require you to yell at whomever you are face to face with if you want to be heard. Their party only lasts a couple of weeks, long enough for them to leave a nymph hoard that will burrow into the ground, then feed quietly on root sap for another 17 years.
the most intriguing is nobody knows why it times its death with bizarre precision: It either lives for 13 years or 17 years! mysteriously accurate biological clocks.
“ALLAH IT IS THAT GIVES UNTO EVERYTHING ITS NATURE .,..,Taha 50
even the famed Evolutionist Charles Darwin in wonder about their lives said .“I do not at all know what to think of your extraordinary case of the Cicadas.” in a letter to Benjamin Walsh of Rock Island, Illinois, October 31, 1868.