Metozoan Diversity

• Container for circulation of oxygen and nutrients and space where internal organs can move independently of each other
• 1. liquid water is efficently incompressible at biologically relevant pressures
• 2. a given amount of liquid water contains a constant volume, but the shape of the volume is free to vary
• 3. Organisms can use muscles to transfer force from one part of the body to another and to change their shape

Body cavity forms between endoderm and mesoderm layers (primary body cavity)

Tripoblasts witha coelom (sencondary body cavity)

Tripoblasts that do not have a coelom

• Coelm formed by evagination of gut
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• Coelom formed by split in mesoderm
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Primary and secondary body cavities

• Internal fluid filled space located between ectoderm and endoderm
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• Body units repeated along a longitudital axis
• A common form of symmetry in animals that:
• 1. have complex or powerful body movements (eg annelids, arthopods, vertebrates)
• OR
• 2. benefit from having multiple reproductive systmes (eg tapeworms- Playhelminthes)
• An evolutionary route to increasing a feature (size, complexity, number of muscles) without evolving totally new features

• Two body units reflected across central (mid-saggital) plane
• Dominant in animals that:
• 1. are mobile and interact with the enviroment in one preferred orientation (anterior end)
• 2. Have distinct ventral and dorsal surfaces
• 3. Have a head where sense organs, brain, and (usually) central mouth are located (cephilization)
• 4. are descendants from organisms with one or more of the above

• Body units distributed around a central axis and/or reflected across multiple planes
• Dominant form of symmetry in animals that:
• 1. have no or little motility
• 2. are filter feeds, sit and wait predators, or have food producing emdosymbionts
• 3. have diffuse sense organs, uncentralized nervous systems, central mouth (no head, no brain)
• 4. are descendants from ancestors with one or more of above

• Condition of having similar shapes or structures organized at or across a specific point, axis, or plane
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• Series of cell movements that forms the three embryonic layers. Migration creates pore that opens to the outside
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• orientation of mitotic axis to embryonic axis and orientation of cells to each other
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• Spiral cleavage
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• 1. Hiearchy of Fundamental Organization- tissues, organs, organ systems
• 2. Early development- cleavage, determincy, gasturlation, developmental tissues
• 3. Body Symmetry
• 4. Body cavities and their development

Multicellularity- cells adhere together and differentiate to form mutually beneficial functions

Heterotrophy-acquire organic carbon and nitrogen from consumption of other organisms

Animal Moltility- active movement of the entire multicellular organism

Colagen based extracellular matrix- cells bound together by collagen, a family of triple helical, coiled, fibrous proteins (eg basement membrane of epithelium); strong, elastic, resilient

Early sequestration of germline cells- cells designed to produce gametes isolated early in development

Hox genes-developmental regulatory genes (transcription factors) that specificy cell identity, arranged in linear clustors in a conserved sequence