BIOL 111 Lecture Notes - Hirudin, Clitellum, Seta

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Published on 26 Jun 2012
Department
Course
Professor
Bio 111 Alanna Houston
October 23, 2007
-Look at animal phylogeny
-Sponges do not have tissues
-Multicellularity has evolved more than once in the evolutionary
history of life.
-
-Bilateral symmetry evolved at D (protostomes and
deuterostomes)
-The first triploblasts (3 layers of cells) also evolved at D
-The flatworms are at F (Lophotrochozoans)
-Protostomes and Deuterostomes split in the Cambrian period
-Animals have cleavage (huge ball of cells from one cell) in
embryonic development:
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Bio 111 Alanna Houston
-
-Protostomes: blastopore becomes mouth and second opening
becomes anus (worms)
-Deuterostomes: blastopore becomes anus and second opening
becomes mouth (humans)
-Digestive tract evolved at D although arrow worms and
lophotrochozoans lost it through evolution and only has a
digestive cavity
-Advantages of digestive tract:
oSpecialization of gut regions
oSequential food processing
oContinuous operation
-One difference between the three groups of worms is body cavity
(coel = cavity)
Acoelomate:
-no coelom (no body cavity)
-solid except for gut space
-flatworms, (cnidarians – diploblasts)
Pseudocoelomate:
-false coelom
-mesoderm lines the outside of the coelom
-nematodes
Coelomate:
-mesoderm lines entire cavity as a ‘peritoneum
-annelids
-A coelom provides hydrostatic support, locomotion, storage, space
for organ development, isolation of digestive tract
PROTOSTOMES
Lophtrochozoans:
-move using cilia
-Annelids:
o15000 species
oSegmented worms
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Document Summary

Multicellularity has evolved more than once in the evolutionary. Bilateral symmetry evolved at d (protostomes and deuterostomes) The first triploblasts (3 layers of cells) also evolved at d. Protostomes and deuterostomes split in the cambrian period. Animals have cleavage (huge ball of cells from one cell) in embryonic development: Protostomes: blastopore becomes mouth and second opening becomes anus (worms) Deuterostomes: blastopore becomes anus and second opening becomes mouth (humans) Digestive tract evolved at d although arrow worms and lophotrochozoans lost it through evolution and only has a digestive cavity. Advantages of digestive tract: specialization of gut regions, sequential food processing, continuous operation. One difference between the three groups of worms is body cavity (coel = cavity) No coelom (no body cavity) solid except for gut space flatworms, (cnidarians diploblasts) Mesoderm lines the outside of the coelom. Mesoderm lines entire cavity as a peritoneum". A coelom provides hydrostatic support, locomotion, storage, space for organ development, isolation of digestive tract.

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