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larva, in zoology

(Encyclopedia)larva, independent, immature animal that undergoes a profound change, or metamorphosis, to assume the typical adult form. Larvae occur in almost all of the animal phyla; because most are tiny or micro...

pearl, gem

(Encyclopedia)pearl, hard, rounded secretion formed inside the shell of certain mollusks, used as a gem. It is secreted by the epithelial cells of the mantle, a curtain of tissue between the shell and body mass, an...

Platyhelminthes

(Encyclopedia)CE5 A. Planaria, representative of the phylum Platyhelminthes B. Internal anatomy of Planaria Platyhelminthes plătˌēhĕlmĭnˈthēz [key], phylum containing about 20,000 species of soft-bodied,...

diseases of plants

(Encyclopedia)diseases of plants. Most plant diseases are caused by fungi, bacteria, and viruses. Although the term disease is usually used only for the destruction of live plants, the action of dry rot and the rot...

virus

(Encyclopedia)CE5 Structure of a tobacco mosaic virus, an RNA-containing virus virus, parasite with a noncellular structure composed mainly of nucleic acid within a protein coat. Most viruses are too small (100...

Chordata

(Encyclopedia)CE5 Common features in representative groups of the phylum Chordata Chordata kôrdāˈtə, –däˈ– [key], phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal ...