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Annelida

(Encyclopedia)CE5 A. The earthworm, Lumbricus terrestris, representative of the phylum Annelida. B. Internal anatomy of an earthworm. Annelida ənĕlˈĭdə [key] [Lat., anellus=a ring], phylum of soft-bodied, ...

mitosis

(Encyclopedia)CE5 Mitosis in a body cell of an animal mitosis mītōˈsĭs, mĭ– [key], process of nuclear division in a living cell by which the carriers of hereditary information, or the chromosomes, are ex...

tapeworm

(Encyclopedia)tapeworm, name for the parasitic flatworms forming the class Cestoda. All tapeworms spend the adult phase of their lives as parasites in the gut of a vertebrate animal (called the primary host). Most ...

birth control

(Encyclopedia)birth control, practice of contraception for the purpose of limiting reproduction. Although contraceptive techniques had been known in ancient Egypt, Greece, and Rome, the modern movement for birth ...

mutation

(Encyclopedia)mutation, in biology, a sudden, random change in a gene, or unit of hereditary material, that can alter an inheritable characteristic. Most mutations are not beneficial, since any change in the delica...

reptile

(Encyclopedia)reptile, name for the dry-skinned, usually scaly, cold-blooded vertebrates (see Chordata) of the order Reptilia. Reptiles are found in a variety of habitats throughout the warm and temperate regions (...

seaweed

(Encyclopedia)seaweed, name commonly used for the multicellular marine algae. Simpler forms, consisting of one cell (e.g., the diatom) or of a few cells, are not generally called seaweeds; these tiny plants help to...

rock music

(Encyclopedia)rock music, type of music originating in the United States in the mid-1950s and increasingly popular throughout much of the world. A turning point in rock music occurred in the mid-1970s in the ...

cancer, in medicine

(Encyclopedia)cancer, in medicine, common term for neoplasms, or tumors, that are malignant. Like benign tumors, malignant tumors do not respond to body mechanisms that limit cell growth. Unlike benign tumors, mali...

fern

(Encyclopedia)CE5 Life cycle of a fern fern, any plant of the division Polypodiophyta. Fern species, numbering several thousand, are found throughout the world but are especially abundant in tropical rain fores...