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Mimicry: a tale of natural born imposters

Mimicry is a phenomenon where organisms resemble other species or objects for their own advantage. It can be found in animals, plants and minerals. For example, you might find a plant that resembles some venomous insect or vice versa some predator that resembles a plant. This is due to evolution; organisms are subjected to changes that cause them to acquire these similarities, making them appear threatening when they aren't or harmful when they are in fact dangerous. It shouldn't be mistaken with convergent evolution which is when two organisms that lack common ancestor, evolve to have similar characteristics.
Mimicry is classified in two ways: Defensive and Aggressive. The first, defensive mimicry, is where a harmless species imitates the appearance of a harmful one. The idea behind this is that predators will avoid the harmful species if they mistake the mimic for the real thing. The second type of mimicry, aggressive, is where a harmful species mimics the appearance of a harmless one. The idea is that prey will get closer to the predator if they think it is harmless, they might even try to feast on the predator.
The mimic octopus (Thaumoctopus mimicus) is probably the best example of defensive mimicry. It is found in the Indian Ocean and is known for looking like other sea creatures. The mimic octopus has the ability to change its skin color, shape and texture. This allows it to imitate 15 different species of other animals, such as sea snakes and jellyfish. The mimic octopus can change its shape and color as well as imitate the movement of other dangerous sea creatures. It was discovered just recently (in 1998), most probably because they hide so well.
One of the best examples of aggressive mimicry is Iranian spider-tailed viper. It uses its tail, which resembles a spider, to trick birds into coming closer. The bird thinks that the tail is a tasty meal and it gets close enough for the viper to strike. And this trick never gets old, even if the bird has seen this species before it will still go for the tail.
And probably the best example of mimicry from fiction (and my personal favorite) is alien from cult classic science fiction movie "The thing" which can mimic any organism it comes in contact with.
This is mimicry in a nutshell; organisms that resemble other objects in order to survive. It is a fascinating phenomenon that can be found throughout the natural world. Although it may not be the most popular topic, mimicry offers insight into evolution and organisms' behavior in their natural habitat.

When immune system goes rogue

Immune system is a system of the body that protects it from all foreign substances from the outside (viruses, bacteria, fungi, etc.) and controls the destruction of failed or outdated cells (for example, it is immunity that protects us from tumour formations). In order for immune cells not to destroy the cells of their own body, there is immunological tolerance.

Most healthy poisons in the world

While plants do their best to scare away those who want to eat them by producing all sorts of complex poisons and toxins, ironically, some of them are now used by humans only because of those very poisons.

Banana republic the beginning

One of the co-founders of the United Fruit Company (now Chiquita) was Minor Cooper Keith. He built a railroad in Costa Rica and planted many banana trees along the way to feed the workers. When the government could no longer fund the project, Keith had to come up with something to pay back the huge loan he had received. He decided to start using the newly built railroad to export bananas to the United States.

Appendix - a secondary immune organ

Although appendix is no longer used by humans for digestive purposes it still contains a high concentration of lymphoid tissue. Lymphoid tissue is essential for the immune system and may help encourage the growth of some types of beneficial gut flora.

How to survive if you're slow as a sloth?

A sloth can move slowly, but movement is not his primary defense method. Camouflage is a great way to go undetected. And this is where sloths have become experts over a long period of their evolution.