The tardigrade is one fascinating creature. It can survive anything from extreme cold to extreme heat. It can even survive the vacuum of space. Recently, it’s come to the attention of scientists that its DNA is just as interesting. A large portion of its DNA doesn’t actually come from reproduction. Rather, it comes from other animals. It actually steals portions of DNA from over animals and incorporates it into its own genetic makeup.
Tardigrades have been found in various environments. They have even been found in Antarctica with the ability to withstand temperatures as low as -80 degrees Celsius. However, they seem to be found anywhere water is found. They can mainly be found in and around moss and lichen. There are over 400 species of tardigrade found since first discovered by Goetz in 1773. They have 4 pairs of limbs with claws or discs. They have soft bodies and move like a bear.
The diet of a tardigrade is primarily plant cells. It has a pharyngeal bulb which allows them to pierce the cell of a plant or animal. Once it pierces the cell wall, it then starts to suck the contents of the cell. They have also been known to eat rotifers and even other tardigrades.
Reaching just over 1 mm, this creature has been the fascination of biologist and scientists for years. It was once thought that nothing could live in the emptiness of space. However, the tardigrade is the reason why scientists no longer believe this.
The tardigrade, also known as a water bear, is considered to be an extremophile. Meaning, it can survive in unlivable conditions. It can survive years without food and can even live on incredibly low levels of water. In cases where water is short, it can dry itself out. Then, when water is available, it can rehydrate itself. Without food, it can survive up to 10 years. It can also put itself in suspended animation due to lack of oxygen or lack of water in the environment. Even still, they can also survive large amounts of radiation. In fact, they can withstand up far above the amount it would take to cure a human.
In normal circumstances, animals receive their genes from reproduction. Their parents pass on genes to them. However, in some cases, animals can receive genes from outside their genome. This is called horizontal gene transfer. Some genes are coming from another animal. This is caused by the exchange of viruses.
Researchers have recently completed mapping out the genome for the tardigrade. As it turns out, around 17% of its genes have been found to come from other animals. This is the highest that they’ve ever seen and they don’t know why. Most organisms have up to 1%. The highest before seen was around 7%.
This finding comes as a major milestone in researching how life evolves. Traditionally, we’ve always thought the evolution of life as a tree structure with branches moving out from and ever higher trunk. However, more researchers are beginning to see it more like a web.