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Hydras are simple, freshwater animals possessing radial symmetry and contain post-mitotic cells (cells that will never divide again) only in the extremities. [14] All hydra cells continually divide. [15] It has been suggested that hydras do not undergo senescence, and, as such, are biologically immortal. In a four-year study, 3 cohorts of hydra ...
List of aquarium diseases; List of dog diseases; List of feline diseases; List of diseases of the honey bee; List of diseases spread by invertebrates; Poultry disease; Lists of zoonotic diseases, infectious diseases that have jumped from an animal to a human
Fragmentation is a very common type of vegetative reproduction in plants. Many trees, shrubs, nonwoody perennials, and ferns form clonal colonies by producing new rooted shoots by rhizomes or stolons, which increases the diameter of the colony. If a rooted shoot becomes detached from the colony, then fragmentation has occurred. There are ...
Senescence (/ s ɪ ˈ n ɛ s ə n s /) or biological aging is the gradual deterioration of functional characteristics in living organisms. Whole organism senescence involves an increase in death rates or a decrease in fecundity with increasing age, at least in the later part of an organism's life cycle.
Some tortoises show negligible senescence. Negligible senescence is a term coined by biogerontologist Caleb Finch to denote organisms that do not exhibit evidence of biological aging (), such as measurable reductions in their reproductive capability, measurable functional decline, or rising death rates with age. [1]
While habitat fragmentation is often associated with its effects on large plant and animal populations and biodiversity, due to the interconnectedness of ecosystems there are also significant effects that it has on the microbiota of an environment. Increased fragmentation has been linked to reduced populations and diversity of fungi responsible ...
The life span is at least four years. [3] A dense population of Stephanasterias albula was studied at North Lubec, Maine. All the individuals were fairly small, with arm lengths not exceeding 18 mm (0.71 in), but no juveniles were found, suggesting that there had been no recent larval recruitment and that this species may be obligately fissiparous.
A number of diseases have been related to mass die-offs or declines in populations of amphibians, including "red-leg" disease (Aeromonas hydrophila), Ranavirus (family Iridoviridae), Anuraperkinsus, and chytridiomycosis. It is not entirely clear why these diseases have suddenly begun to affect amphibian populations, but some evidence suggests ...