102SN3 - Biology 102 Study Notes Exam 3 Chapter 29...

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Kevin Kelleher, MTC Biology 102 Study Notes Exam 3 1 Biology 102 Study Notes Exam 3 Chapter 29: Introduction to Invertebrates Evolution of Animals - Animal History o the fossil record is more complete for hard-shelled animals; possible evolutionary relationships are primarily worked out by using anatomical criteria o there are over 30 animal phyla - Criteria for Classification o Levels of Organization : animals may have the cellular, tissue, or organ level of organization germ layers refer to the number of layers of tissues most animals are made of 3 tissue layers : endoderm, ectoderm and mesoderm animals with only ectoderm and endoderm are limited to a tissue level of organization animals with three tissue layers develop an organ level of organization o Type of Body Plan animals with a sac plan have an incomplete digestive system with only one opening used for both entrance and exit of food animals with the tube-within-a-tube plan have a complete digestive system with separate entrance and exit to the digestive system; this allows specialization zones along the digestive tract o Types of Symmetry asymmetry : there is no particular symmetry radial symmetry : body parts arranged around an axis, like spokes of a wheel radially symmetrical animals may be sessile (i.e., attached to a substrate or less motile) bilateral symmetry : a body having a right and left, or complementary halves (one longitudinal cut down the center produces mirror halves) bilaterally symmetrical animals tend to be active and move forward cephalization : head development to localize the brain and sensory organs o Type of Coelom true coelomates possess a body cavity or coelom completely lined with mesoderm acoelomates lack a body cavity or coelom although they have mesoderm pseudocoelomates possess a pseudocoelom ; the body cavity is incompletely lined by mesoderm; the cavity develops between the mesoderm and endoderm coelomates are either protostomes or deuterostomes protostomes develop with the first embryonic opening becoming the mouth deuterostomes develop with the second opening becoming the mouth o Segmentation is repetition of body parts along the length of the body among coelomates, molluscs and echinoderms are non-segmented
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Kevin Kelleher, MTC Biology 102 Study Notes Exam 3 2 annelids, arthropods, and chordates are segmented segmentation leads to specialization of parts as they differentiate for specific purposes Multicellularity - Phylum Porifera (~ 5,000 species of sponges ) o sponges have no symmetry and no tissues (unique in the animal world) o sponges remain at a cellular level of organization , having evolved separately from protozoan ancestors o sponges are aquatic, largely marine animals, that vary in size, shape, and color o their saclike bodies are perforated by many pores; Porifera means “pore-bearing o several types of cells are found in a sponge the outer layer of their wall contains flattened
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102SN3 - Biology 102 Study Notes Exam 3 Chapter 29...

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