Evolution, a process that involves living beings and allows us to change to remain, is also a mechanism of nature through which we can elucidate our origin and project a possible future. From the most "simple" beings that inhabit the earth to the most "complex" (and not for that reason better adapted), all living forms are the result of a long history of wise changes that made their way through a long line of extinct species that did not manage to survive.
The idea that the first living beings on Earth are the simplest and least evolved is erroneous; as proof, there is clear evidence in nature that this assertion has confused us for many years. Thus, there are countless examples at all levels of biological organization (from tiny molecules, subcellular organelles, unicellular organisms, and even macroscopic multicellular organisms with large biomasses) that allow us to confirm the opposite.
Among the first animals to inhabit the Earth, we find marine sponges, which appeared approximately 890 million years ago;1 they have as close relatives jellyfish, which share a common ancestor and whose appearance dates back 600 million years. Jellyfish have not only managed to overcome several glaciations and mass extinctions, but in recent decades they have proliferated by invading the oceans, forming large aggregations that now represent them in several places in the world where there was no record of them.
What have jellyfish done from their simplicity and beauty to be able to face climate change, global warming, and ocean acidification? Let us remember that jellyfish are much more than marine animals that sting us and inject toxins. Jellyfish have developed different phases in their life cycle, which makes them able to cope with climate change; they have high collagen content and are a potential source of food that is already consumed in Asian countries.
These simple animals are much more complex than what meets the eye. Recently the genome of several jellyfish species has been described and with this information, it is expected that some impressive biological characteristics that some of them have shown can be explained. For example, the ability to regenerate their tissues, the ability to reverse development to earlier stages, and the ability to generate high amounts of chemical energy to maintain their functions when facing environmental changes such as high temperature and low oxygen.
For all these reasons, we must care for, protect and study jellyfish. In this way, we will understand the biological secrets that make them successful species and we will know how they adapt and survive to changes, which will allow them to be animals capable of remaining and continuing to evolve.
By Adriana Muhlia Almazán, a researcher at CIAD, and Édgar Gamero Mora, a postdoctoral researcher at CIAD.