How to sign: any animal lacking a backbone or notochord; the term is not used as a scientific classification
Categories: animal, animate being, beast, brute, creature, fauna
Within this category: arthropod, brachiopod, bryozoan, coelenterate, ctenophore, echinoderm, ectoproct, entoproct, mollusk, peanut worm, phoronid, rotifer, sponge, Symbion pandora, woodborer, worm, zoophyte