hydra

400x abdomen ability adults age anatomy animal biology body bones cavity cells cilia classification cnidarians cut eggs excretion feet food freshwater genus gillies head hermaphrodites histology hydra hydras hydroids invertebrates larvae limbs lower magnify micrographs morphology mouth mouthparts native nature networks neural neurotoxins oral parasitism photoreceptors phylum physiology pupae regenerate regeneration regions respiration sensory small sprites stem structure symbiosis synapses system temperate tentacles tropical upper wings zoology