- 行业: Government
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NOAA Coral Reef Conservation Program, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
A lobe of the parapodium closer to the ventral side in polychaete worms.
Industry:Natural environment
A polysaccharide made up of chains of N-acetyl-D-glucosamine, a derivative of glucose. Chitin is structurally very similar to cellulose and serves to strengthen the supporting structures of various invertebrates. It also occurs in fungi.
Industry:Natural environment
A species is an interbreeding natural population that is reproductively isolated from other such groups. Species are usually separated by discontinuities, which constitute barriers that prevent, or at least inhibit, an interspecific gene flow and gene exchange. Establishment of reproductive isolation is essential for development of a new species.
Industry:Natural environment
A unidirectional response of motile cells or organisms in which the direction of movement is affected by the gradient of a diffusible substance.
Industry:Natural environment
One of the external openings communicating with the air tubes (tracheae) or book lungs of certain arthropods; a tubular opening, formed from the modified first gill cleft, communicating with the gill cavity of certain ganoid (e.g., gar pike, bowfin) and all elasmobranch fishes.
Industry:Natural environment
Sexual reproduction involving the fusion of male and female gametes and the formation of a zygote.
Industry:Natural environment
