posterior root the posterior, or sensory, division of each spinal nerve, attached centrally to the spinal cord and joining peripherally with the anterior root to form the nerve before it emerges from the intervertebral foramen; each posterior root bears a spinal ganglion that conveys sensory fibers to the spinal cord.he sensory division of each spinal nerve, attached centrally to the spinal cord and joining peripherally with the ventral root to form the nerve before it emerges from the intervertebral foramen.
Freshwater. Many freshwater fish average about 1 to 3 years of life. Some of the more popular species with this short life span include fantail guppies, swordtail platy, mollies, rainbow fish, hatchet fish, corydoras catfish, some cichlids, rasboras and tiger barbs. There are also several fish that live around 3 to 5 years, with proper care and feeding.
Some of them, at a later stage, form large groups living together, but normally are solitary, and some of them act as cleaner fish. Sexual maturity is reached after about 1 year of life. Butterflyfish lifespan is about 3 or more years, with bigger species living longer. The home range of butterflyfish depends on the species, varying from a few square meters to very large territories, which is mainly dependent on food availability.