The robber crab

The coconut crab (Birgus latro) or robber crab is the largest terrestrial arthropod.

In some places it is also called the coconut crab, as it is strong enough to climb coconut trees and steal coconuts. When it decides to eat a coconut, it tears the shell into strips using its pincers and then repeatedly strikes the fruit until it breaks open.

Coconut crabs have a tendency to steal shiny objects, such as watches, jewelry, and dishes left behind by tourists or residents in campsites and backyards.

He is nocturnal, so he is rarely caught stealing during the day.

Despite being a crab, it is a terrestrial type and is capable of terrorizing the neighborhood where it lives. It loves to wander through inhabited areas and steal garbage cans and anything else it can find to eat.

It eats everything: besides coconuts and other fruits, it ingests vegetation, carrion from dead birds, and other crabs. Biologist Michelle Drew caught some crabs ambushing young chickens and even kittens.

Coconut crabs have developed a keen sense of smell, which evolved convergently with that of insects and which they use to find potential food sources. Crabs that live in water have organs called aesthetascs on their antennae to determine both the concentration and direction of a scent.

The aesthetascs of coconut crabs are shorter and more direct than those of aquatic species. This allows them to detect interesting odors from greater distances and search for food more effectively.

They do not attack humans, as long as the humans do not bother them.

Although they are not poisonous by nature, they can acquire toxins that make them poisonous through their diet. There are cases where they have eaten plants containing toxins and have become poisonous.

When the tide is high, they climb trees to avoid being killed, thus obtaining the necessary food and protection.

The largest coconut crabs ever recorded were 1 meter long and weighed up to 17 kilograms, which is spectacular for a terrestrial arthropod.

In aquatic environments, it is possible to find even larger specimens.

They are extremely docile; in Tokyo, for example, they are sold as pets and kept in cages strong enough to withstand their powerful pincers.

Despite their size, little is known about Earth's coconut thief populations. They have never been thoroughly studied, so it is unknown how many specimens remain in the world.

They are classified as a data-deficient (DD) species by the International Union for Conservation of Nature, meaning that experts do not know enough to determine whether or not this species is threatened with extinction.

"Historically, this type of crab was targeted by hunters, but not for many decades," says Heather Koldewey of the Zoological Society of London. Nowadays, many serve as prey for rats, which have been introduced to the islands where they live.

Koldewey and his colleagues are now conducting the first major survey of coconut thief populations.

The biologist says it is still too early to define the situation of these animals, as several more years of surveys will be needed.

But, according to her, rats represent a problem, especially on islands with little vegetation. Even so, scientists have observed that, sometimes, crabs get the upper hand and eat the rats.

Coconut thieves live in underground burrows lined with coconut husk fibers.

Their life expectancy is quite high; they can reach their maximum size between the ages of 40 and 60—that is, if they don't encounter any predators or a terrified human. There are reports of some specimens over one hundred years old.

Like other arthropods, coconut crabs use their exoskeleton and shed it periodically as they grow. Therefore, on average, they seek the safety of a burrow once a year to molt.

It is during this period that it becomes most vulnerable, because once it emerges from this rigid shell, in order to accelerate the development of its new armor, it consumes its old exoskeleton.

Millions of years ago, these crabs lived peacefully on islands without large mammalian predators, which allowed them to reach their incredible size.

There is no confirmation of the suspicion that one of the representatives of the species reached the presidency of the Chamber of Deputies.