Biological immortality

Biological immortality refers to a state where the rate of mortality from senescence is stable or decreasing, thus decoupling it from chronological age. Various unicellular and multicellular species, including some vertebrates, achieve this state either throughout their existence or after living long enough. A biologically immortal living being can still die from means other than senescence, such as through injury or disease.

Overview

In most of the animal kingdom, mortality increases as species age. This is not the case for certain species, which scientists describe as being "biologically immortal". These species do not age and, therefore, do not die of old age or age-related diseases. However, they can still die from disease, injury, or predation.

Mechanisms

The mechanisms of biological immortality in different organisms are not always well understood. In some cases, such as with certain hydra and jellyfish, the organisms continually regenerate their cells, effectively avoiding aging. Other organisms, like the lobster, continually grow throughout their lives and have been known to reach impressive ages.

Examples

Hydra

The hydra, a simple freshwater animal, does not age or die of old age. Instead, it continually regenerates its cells. This is due to the hydra's high concentration of stem cells, which can continually divide and differentiate into various cell types.

Lobsters

Lobsters are another example of an organism that is biologically immortal. They continue to grow throughout their lives and do not have a natural lifespan. However, lobsters can still die from disease or injury.

Turritopsis dohrnii

The Turritopsis dohrnii, also known as the immortal jellyfish, is capable of reverting its cells back to their earliest form and growing anew, effectively making it immortal.

See also

• Senescence
• Immortality
• Aging in dogs
• Maximum life span
• List of long-living organisms

References

• Biological_immortality
• 
  Hydras
• 
  Polycelis felina