Scientists estimate that there have been about 500 million different species on Earth. Some of them were anecdotal; others, on the other hand, populated our planet for millions of years until they became extinct; and others continue to do so. The success of the species depends on the individuals thriving and reproducing; otherwise, only the best-adapted will thrive. But what does it depend on whether individuals of a species survive long? How long is the longest a single individual can live?
Strictly speaking of the animal kingdom, there are species whose specimens survive an astonishingly long time, at least, what humans are used to. There are individuals of a type of mollusk, for example, that have been alive since the time of Emperor Charles V; fish that have survived since the French Revolution or turtles that have been alive since World War II.
What gives an animal long life? In humans, research in the field of biomedicine points to telomeres as one of the keys to longevity, aging and even cancer. In animals, biologists have spent years trying to sequence the genomes of some of the longest-lived species to try to find something like an ‘exile from immortality’.
The immortal jellyfish
Turritopsis nutricula (pictured) is one of the known organisms that can reverse their life cycle to the polyp stage even after sexually maturing, defining itself as the only ‘immortal’ organism in the animal kingdom. Therefore, the animal is of primary importance in aging research. In 2016, the mitochondrial genome of this jellyfish was sequenced, identifying specific gene variations in the different subspecies.
In addition to this exceptional species of jellyfish, the rest of the animals that we collect in this list are the longest-lived of which there is evidence. It should be noted that most of them live in the deep sea: mollusks, urchins and fish. It is here, under the oceans, that some of the oldest species, which have been on Earth the longest, still survive. Many of them, in addition, are threatened by fishing activity, usually due to their amazing characteristics.
Let’s start our review of the ten oldest animals on Earth.
