التعريف: A liquid tissue; its major function is to transport oxygen throughout the body. It also supplies the tissues with nutrients, removes waste products, and contains various components of the immune system defending the body against infection.
التعريف: Description of the relationships among individuals within a population of organisms, including reproductive relationships (mating system), relationships within each sex, adult – young interactions, helpers and cooperation (group living).
التعريف: Solitary animals are those that spend a majority of their lives without others of their species, with possible exceptions for mating and raising their young. The antonym to a solitary animal is a social animal.