650 million years ago to 530 million years ago, animal phyla {invertebrate} evolved from protozoa.
types
Invertebrate types include anthozoans, crustaceans, ctenophors, echinoderms, insects, mollusks, stars, and worms. Lower invertebrates include ctenophors, coelenterates, flatworms, gastrotricha, proboscis worms, rotifers, roundworms, sipunculans, and sponges. Higher invertebrates include acorn worms, annelids, arthropods, clictors, lampshells, molluscs, moss animals, onychophora, phoronids, and starfish.
stimuli
Invertebrates sense chemical stimuli. Invertebrates can learn by touch but cannot distinguish shapes. Invertebrates have no joint receptors or proprioceptors, do not know muscle contraction or relaxation degree, and do not know body position. Invertebrates do not feel motivations, such as hunger or thirst.
learning
Invertebrates can learn to manipulate objects.
Biological Sciences>Zoology>Kinds>Invertebrate
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Date Modified: 2022.0224