Needham's sac/organ (MOLL: Cephalopoda) In males, a specialization of the sperm duct for formation and storage of spermatophores; spermatophoric sac.
negative geotropism Movement directed away from the earth's gravitational force.
negative phototropism The tendency to retreat from light.
negative tropism The tendency to retreat from stimuli.
nekton n. [Gr. nektes, swimmer] Organisms that swim in the open water, i.e., jellyfish, squid, fishes, turtles, seals and whales; necton. see seston.
nema n. [Gr. nema, thread] (NEMATA) Any individual of the phylum Nemata; a nematode.
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