BIOL 211 Lecture Notes - Lecture 7: Ventral Nerve Cord, Gastrulation, Cephalization
3 Oct 2017
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Document Summary
Humans more closely related to deuterostomes than earthworms. 5 known lineages> crinoidea, asteroidean, ophiuroidea, echinoidea, and holothuridea. Adults are radial symmetrical but larve are bilaterally symmetrical. Unique water vascular system> network of hydraulic tubes used in locomotion, feeding, gas exchange, and excretion. Muscle and nerve tissue but no cephalization in adults. Population explosions of the crown of thorns can severely damage coral reefs> control with toxins. Class echinoidea (sea urchins)- useful model system to study development in deuterostomes. Class holothuroidea (sea cucumber) some species harvested for commercial consumption. Includes animals that are most familiar to us (including us) Divided into invertebrate chordate and one vertebrate chordate. Notochord- flexible rod located between nerve cord and gut. Dorsal, hollow nerve cord other phyla have solid ventral nerve cord. Called lancelets because of their blade like shapes.
