Protostome and Deuterostome

Protostome and Deuterostome - spets favoring segmentation...

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Protostome and Deuterostome Coelomates fall into either protostomes or deuterostomes , depending on how their embryos develop, as shown in Figure 5. Protostomes (from the Greek meaning literally "first mouth") are coelomates whose embryonic development makes a blastopore (the first opening in the blastula) that later develops into a mouth. Deuterostomes ("second mouth") are coelomates whose embryonic development produces a blastopore that later forms an anus, with a second opening forming the mouth (hence the designation of "second mouth"). Vertebrates are deuterostomes.
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Segmented Bodies Some animals have their bodies divided into segments, as shown in Figure 6. Segmentation allows them to specialize certain segments, such as for antennae, eyes, claws, etc. Humans, insects, and earthworms are examples of segmented animals. The systematic value of segmentation has been downplayed, with most
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Unformatted text preview: spets favoring segmentation arising from convergent evolution. However, the genes controlling segmentation in each of these groups are the same, leading to a rethinking of the taxonomic value of segmentation. Sponges: The Phylum Porifera The phylum Porifera ("pore-bearing") consists of approximately 5,000 species of sponges. These asymmetrical animals have sac-like bodies that lack tissues, and are usually interpreted as representing the cellular level of evolution. Cells from fragmented sponges can reorganize/regenerate the sponge organism, something not possible with animals that have tissues. Most zoologists consider sponges as offshoots that represent an evolutionary dead-end., although others consider some groups of sponges as being related to other animal groups. Sponges are aquatic, largely marine, animals with a great diversity in size, shape, and color....
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This note was uploaded on 11/29/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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Protostome and Deuterostome - spets favoring segmentation...

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