19 - BIO LECTURE NOTES (2/24/09) Introduction The...

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BIO LECTURE NOTES (2/24/09) Introduction The deuterostomes include the largest-bodied and some of the most morphologically complex of all animals Deuterostomes are not as numerous as protostomes, but they act as key predators and herbivores in most marine and terrestrial habitats An Overview of Deuterostomes Evolution The deuterostomes were initially grouped together because they all undergo early embryonic development in a similar way Most biologists recognize 4 phyla of deuterostomes: the echinodermata, the hemichordata, the xenoturbellida, and the chordata Echinoderms, hemichordates, and xenoturbellida are invertebrates: the chordates include both invertebrate and vertebrate phyla However, their adult plans, feeding methods, modes of locomotion. .. What is an Echinoderm? Echinoderms (“spiny-skins”) are named for the spines or spikes observed in many species This phylum is defined by several adaptations The first is that larvae are bilaterally symmetric, as are other deuterostomes, but adults are radially symmetric Echinoderms are defined by unique morphological feature: the water vascular system , a series of branching, fluid-filled tubes and chambers that forms a hydrostatic skeleton An important part of this system is tube feet , which are elongated, fluid-filled structures Podia are sections of the tube feet that project outside of the body and are involved in motion along a substrate
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19 - BIO LECTURE NOTES (2/24/09) Introduction The...

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