Negligible senescence refers to the failure of a few select animals to display symptoms of aging. More specifically, negligibly senescent animals do not have measurable reductions in their reproductive capability with age, or measurable functional decline with age. Death rates in negligibly senescent animals do not increase with age as they do in senescent

Senescence

Senescence or biological aging is the change in the biology of an organism as it ages after its maturity. Such changes range from those affecting its cells and their function to those affecting the whole organism...

 organisms. There are strong scientific grounds to state that humans of advanced ages are also having negligible senescence phenomena.

Some fish, such as some varieties of sturgeon

Sturgeon

Sturgeon is the common name used for some 26 species of fish in the family Acipenseridae, including the genera Acipenser, Huso, Scaphirhynchus and Pseudoscaphirhynchus. The term includes over 20 species commonly referred to as sturgeon and several closely related species that have distinct common...

 and rockfish, and some tortoises and turtles are thought to be negligibly senescent. The age of a captured fish specimen can be measured by examining growth patterns similar to tree rings on the otoliths (parts of motion-sensing organs).

Study of negligibly senescent animals may provide clues that lead to better understanding of the aging process and influence theories of aging

Evolution of ageing

Enquiry into the evolution of ageing aims to explain why almost all living things weaken and die with age. There is not yet agreement in the scientific community on a single answer...

. The phenomenon of negligible senescence in some animals is a traditional argument for attempting to achieve similar negligible senescence in humans by technological means.

Some examples of maximum observed life span of organisms thought to be negligibly senescent are:

• Rougheye rockfish (Sebastes
  Sebastes
  Sebastes is a genus of fish in the family Sebastidae , most of which have the common name of rockfish. Most of the world's almost 110 Sebastes species live in the north Pacific, although two live in the south Pacific/Atlantic and four Sebastes is a genus of fish in the family Sebastidae (though...
  
   aleutianus)—205 years
• Aldabra Giant Tortoise
  Aldabra Giant Tortoise
  The Aldabra giant tortoise , from the islands of the Aldabra Atoll in the Seychelles, is one of the largest tortoises in the world....
  
  —255 years
• Lobster
  Lobster
  Clawed lobsters comprise a family of large marine crustaceans. Highly prized as seafood, lobsters are economically important, and are often one of the most profitable commodities in coastal areas they populate.Though several groups of crustaceans are known as lobsters, the clawed lobsters are most...
  
  s are believed to live 100 or more years.
• Hydra
  Hydra (genus)
  Hydra is a genus of simple fresh-water animal possessing radial symmetry. Hydras are predatory animals belonging to the phylum Cnidaria and the class Hydrozoa. They can be found in most unpolluted fresh-water ponds, lakes, and streams in the temperate and tropical regions and can be found by...
  
  s are observed to be biologically immortal
• Sea anemone
  Sea anemone
  Sea anemones are a group of water-dwelling, predatory animals of the order Actiniaria; they are named after the anemone, a terrestrial flower. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Zoantharia. Anthozoa often have large polyps that allow for digestion of larger...
  
  s generally live up to 60–80 years
• Freshwater pearl mussel
  Freshwater pearl mussel
  The freshwater pearl mussel, scientific name Margaritifera margaritifera, is an endangered species of freshwater mussel, an aquatic bivalve mollusc in the family Margaritiferidae....
  
  —210–250 years
• Quahog clam—405 years