The skin is the largest organ of the human body and of all mammals. In the average adult it weighs around six pounds, which is nearly twice the weight of the human brain or liâ¦ver. Internally, the largest organ is the liver which weighs around 1.6 pounds. A curmudgeon with years of practice.
n. pl. species. 1. Biology A group of closely related organisms that are very similar to each other and are usually capable of interbreeding and producing fertile offspring. The species is the fundamental category of taxonomic classification, ranking below a genus or subgenus.. pl. species. 1. Biology A group of closely related organisms that are very similar to each other and are usually capable of interbreeding and producing fertile offspring. The species is the fundamental category of taxonomic classification, ranking below a genus or subgenus.
1 Phylogenetic species concept: a species is a tip on a phylogeny, that is, the smallest set of organisms that share an ancestor and can be distinguished from other such sets. 2  Under this definition, a ring species is a single species that encompasses a lot of phenotypic variation. researchers choice of species concept often reflects his or her research focus. Making that decision requires the scientist to commit to a species concept. For most purposes and for communication with the general public, the biological species concept is used.