vertebrates

n phylum or class of elongated wormlike parasites that live in the intestines of vertebrates: spiny-headed worms

n any of various worms living parasitically in intestines of vertebrates having a retractile proboscis covered with many hooked spines

plural of acanthocephalan n any of various worms living parasitically in intestines of vertebrates having a retractile proboscis covered with many hooked spines

It originates in the same way as the lungs of air-breathing vertebrates, and in the adult may retain a tubular connection with the pharynx or esophagus. A sac or bladder full of air in an animal or plant

the vascular fetal membrane that lies below the chorion and develops from the hindgut in many embryonic higher vertebrates (reptiles, birds and mammals)