Check out this answer from Consensus:
While humans and other higher animals are intrinsically mortal, certain simpler organisms exhibit traits that suggest they may be biologically immortal. The presence of pluripotent stem cells and the ability to regenerate and rejuvenate tissues are key factors in the potential immortality of these species. Further research into the mechanisms of germline immortality and the regenerative abilities of simple animals may provide valuable insights into the aging process and potential ways to extend lifespan in higher organisms.
The concept of biological immortality has fascinated scientists and the general public alike for centuries. While the idea of living forever remains a distant dream for humans, certain species exhibit traits that suggest they may be biologically immortal. This article explores the mechanisms and examples of biological immortality in various organisms, drawing on recent research findings.
Biological Immortality in Simple Animals
Basal Metazoans
Research has shown that some of the simplest animals, such as ctenophores (comb jellies), sponges, placozoans, cnidarians (hydras, jellyfish, corals, and sea anemones), and myxozoans, exhibit remarkable longevity and potential immortality. A key determinant of this longevity is the presence of large numbers of pluripotent stem cells, which enable these organisms to regenerate and rejuvenate themselves continuously1. This regenerative ability is a crucial factor in their potential immortality.
Flatworms
Flatworms, particularly planarians, are another group of simple animals that demonstrate biological immortality. These organisms possess a high capacity for regeneration due to their abundant pluripotent stem cells. This regenerative ability allows them to replace damaged or aging tissues, effectively maintaining their youthfulness and extending their lifespan indefinitely1.
Germline Immortality
Caenorhabditis elegans
The nematode Caenorhabditis elegans provides a fascinating example of germline immortality. Germ cells in these organisms can be passed from one generation to the next indefinitely, harboring rejuvenation mechanisms that enable them to proliferate for eons. Studies on C. elegans mutants that reproduce normally for several generations but eventually become sterile have shed light on the biochemical pathways required to rejuvenate the germline. These findings suggest that multiple mechanisms are involved in maintaining germline immortality2.
The Germline-Soma Dichotomy
The concept of germline immortality versus somatic cell mortality is a central puzzle in gerontology. While germ cells can be passed on indefinitely, somatic cells are typically only needed for a single generation and are then discarded. This dichotomy raises questions about why and how the somatic part of higher animals has evolved to be mortal, while the germline remains free of progressive deterioration3.
Are there species that are biologically immortal?
Janek Urvik has answered Near Certain
An expert from University of Tartu in Anti-Ageing
From the the animal kingdom, the most famous and only example, I know of, is the jellyfish species Turritopsis dohrnii. That is due to it’s ability to revert it’s life cycle to polyp stage, when faced with harsh conditions. On a cellular level, the species has the unique ability to revert it’s somatic cells to stem cells, or in other words to reverse their programming. This ability is of great interest to scientists, trying to create stem cells in order to repair damaged tissues.
In case of unicellular organisms symmetrically dividing yeast and bacteria are also immortal in ideal conditions, for in the process of dividing into two equal daughter cells, the cell goes through a kind of reprogramming to regain it’s youthfulness.
Are there species that are biologically immortal?
David Gems has answered Near Certain
An expert from University College London in Biology
A more exact way to put this question is: Are there species that do not exhibit senescence (the deteriorative aspect of the ageing process)? An absence of senescence would not lead to immortality, due the the presence of other causes of death. For example, it has been calculated that if human beings were freed from senescence then average human lifespan would be around 1,200 years, and maximum lifespan around 25,000 years. This assumes current rates of mortality from other causes, which seems unrealistic given current levels of human folly (e.g. with respect to climate change and vaccination). It is difficult to prove that any particular organism does not senesce, but many species appear not to, mostly very simple organisms and plants, but not higher animals. Examples include the tiny freshwater polyp Hydra vulgaris, where senescence could not be detected, and organisms showing great longevity, such as up to 11,000 years in the deep sea sponge Monorhaphis chuni and up to 11,700 years in creosote bushes.
Are there species that are biologically immortal?
Zac Wylde has answered Likely
An expert from UNSW Sydney in Evolutionary Biology, Entomology, Anti-Ageing, Behavioural Science, Reproductive Biology
Evolutionary biologists know ageing is a highly “plastic” process influenced by many factors including diet, climate, genetics and even the age at which our grandparents conceived our parents. But, we don’t know why some species age more slowly than others.
Research has shown several species appear not to age. For example, the “immortal” jellyfish Turritopsis dohrnii can revert to a juvenile stage of life and seemingly escape the process of ageing.
To figure out why some species age better than humans, we have to understand so-called “epigenetic changes” which alter our DNA expression throughout the ageing process.
Epigenetic changes are mechanisms that can determine which genes are turned on or off in offspring. They have a huge influence on the course of a species’ evolution.
Understanding these mechanisms could also help us understand why humans and other animals evolved to age in the first place.
I have adapted this answer from my original article in The Conversation
Are there species that are biologically immortal?
Nazif Alic has answered Near Certain
An expert from University College London in Genetics, Anti-Ageing, Cell Biology
There are some animal species that are biologically immortal. This means that they can be killed but they will not die simply due to old age. An often-used example is the hydra.