Why are cockroaches so strong? They have a very hard exoskeleton, they breathe through different parts of their body, they have a decentralized nervous system, they can eat anything, they have strong immune systems, and they don’t need to eat and drink for long periods of time.
A cockroach is not one insect but a family. There are 4,600 different types of cockroaches. 30 of these species are associated with people. The smallest cockroach is the Mediterranean spotted cockroach, and they grow to be about 1 cm long. The largest cockroaches are the Megaloblatta longipennis, the giant burrowing cockroach and the Madagascar hissing cockroach. They can all grow to be over 10 cm long.
Most of the largest cockroaches live in jungles or very hot places. The cockroaches that are the biggest pests are the American cockroach, the German cockroach, and the Asian cockroach. Interestingly, the American cockroach is from Africa and they were introduced into America in the 17th century. Likewise, the German cockroach is from either Africa or Southeast Asia and not Germany. All of these cockroaches are huge pests and have evolved to live with humans. So, why are they so strong and so hard to kill?
The first reason cockroaches are so strong is because of their diet. Many insects live on a small variety of foods and they can be wiped out by eliminating that food. This can be done intentionally or accidentally. The impact of this can be seen by the rapidly declining number of insects in the world. This doesn’t work with cockroaches because they can eat almost anything. They are omnivores and scavengers. They look for meat, fats, sugars, and starches, but they will eat anything. Cockroaches have been known to eat fingernails, soap, glue, books, and beer. They like fermenting foods and they will even eat dirty clothes. It is very rare that a cockroach can’t find something to eat. They have an exceptional sense of smell and are very adroit at finding food.
The second reason is they are very difficult to starve. They are cold blooded insects and have a very slow metabolism. If you locked a cockroach in a jar with no food or water, it could survive for a week. If it had water, it could go for over a month. This is one of the reasons why cockroaches are famous for being able to keep going after their heads have been cut off.
The third reason is that they have an extremely strong exoskeleton. Tests have shown that their exoskeletons can withstand over 900 times their own body weight. They are also able to flatten themselves to avoid damage. The plates of their exoskeletons are attached by a stretchy membrane. If you stood on one, they would be able to flatten themselves to the floor and their hard exoskeletons would allow them to press into the sole of your shoe, rather than being squashed. They also have sharp spines on their legs, which allow them to grip the floor even when being squashed and to escape.
The fourth reason is that they don’t only breathe through their heads. They have a series of pores over their exoskeleton that they can take oxygen in through. This is another reason why they can survive with no head. These pores are called spiracles, and they are like valves that open to release carbon dioxide and to take in oxygen.
The fifth reason is the cockroach’s nervous system. They have a collection of nerves in their head that forms their brain. However, they also have other ganglia (collections of nerves) in different places down their bodies. These other ganglia can receive stimulus and move parts of the cockroach. They are hard to kill because they can still move if part of their nervous system is destroyed.
The sixth reason is they have a very strong immune system. They have genes that can take the toxins out of food that might kill other insects. They have also evolved immunity to a lot of different pesticides.
The last reason is that they are so fast. The American cockroach has been clocked at 5.4 km/h. That means they were running 50 body lengths a second. If you translated that up into human size, it would mean that a human would be running at 330 km/h. Our muscles and skeletons would not survive a speed like that.
It is said that cockroaches will be the only things left after a nuclear war. That is not completely true. They can survive fifteen times more radiation than we can, but it is still fatal to them. One reason they are stronger than us with regards to radiation is that it affects dividing cells the most and cockroach cells only divide when they are molting, which is about once a week. If they are not molting, they will be able to survive a lot of radiation. It could still kill them though. And this is what I learned today.
Photo by Roger Brown: https://www.pexels.com/photo/cockroaches-on-white-background-5149756/
Sources
https://backyardbrains.com/experiments/roboRoachSurgery
https://en.wikipedia.org/wiki/American_cockroach
https://en.wikipedia.org/wiki/German_cockroach
https://www.terro.com/articles/why-are-cockroaches-so-hard-to-kill