User:Igor233/Negligible senescence

Negligible senescence refers to a very few animals that do not 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 organisms.

Some fish, such as some varieties of sturgeon and rockfish, and some tortoises and turtles are thought to be negligibly senescent.

In fish, age of a captured specimen can be measured by examining growth patterns similar to tree rings on the otoliths (parts of motion sensing organs).

Of course, species displaying negligible aging still die of other causes and so extremely old individuals are extremely rare. Since relatively few animals have been examined, the ultimate life span achievable by such an animal is not known.

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

Maximum observed life spans of some organisms thought to be negligibly senescent:
 * Rougheye rockfish sebastes aleutianus 205 years.
 * Aldabra Giant Tortoise 255 years