CH32IntrotoAnimalsLecturetopost[1]

CH32IntrotoAnimalsLecturetopost[1] - Major groups of...

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Major groups of animals are defined by the design and construction of their basic body plan, which differs in the number of tissues observed in embryos, symmetry, the presence or absence of a body cavity, and the way in which early events in embryonic development proceed.
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Recent phylogenetic analyses of animals have shown that there were three fundamental splits during evolutionary history, resulting in two protostome groups (Lophotrochozoa and Ecdysozoa) and the deuterostomes . The most ancient animal group living today is the sponges. The closest living relatives to animals are choanoflagellates, a group of protists. Within major groups of animals, evolutionary diversification was based on innovative ways of feeding and moving. Most animals get nutrients by eating other organisms, and most animals move under their own power at some point in their life cycle.
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An Introduction to Animals Why Do Biologists Study Animals? A. Animals are heterotrophic. 1. They obtain energy and carbon compounds from primary producers, photosynthetic organisms such as plants, bacteria and protists. 2. Some animals are consumers that eat the primary producers. 3. Some animals are predators that eat the consumers. B. Animals are fascinating and diverse. 1. They are the most species-rich and diverse multicellular lineage of organisms. 2. To understand the diversity of life, it is important to understand how animals became so diverse. C. Humans depend on animals for food, transportation, and power. D. Humans are animals! 1. We need to study other animals to understand ourselves. 2. Most testing and genetic studies done on other mammals.
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II. How Do Biologists Study Animals? A. Animals 1. are a monophyletic group of multicellular eukaryotes. 2. move on their own and are heterotrophs. 3. lack cells walls- have a supportive extracellular matrix. 4. are the only lineage with muscle and nervous tissue. 5. can reproduce sexually and asexually, but do not exhibit alternation of generations. 6. are extremely diverse, with 34 phyla having distinct morphological features.
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B. Analyzing Comparative Morphology 1. Animals are eating and moving machines. a. Variation in mouth and limb morphology underlies the variation in eating and moving. b. However, the basic animal body plan is remained relatively unchanged and is defined by: (1) Number & types of tissues in the body (2) Type of body symmetry and degree of cephalization (3) Presence or absence of a fluid-filled cavity (4) Steps of early embryonic development
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2. The Evolution of Tissues a. Sponges are considered parazoans (“beside animal”); they have specialized cell types, but lack tissues . b. All other animals - eumetazoans (“ truly-among-animals”); they have two or more different tissue types. c. Diploblasts (“two-sprouts) have two tissue layers ( ectoderm & endoderm ) .
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