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Animal Body Plans. Adapted fromhttp://userwww.sfsu.edu/~biol240/labs/lab_16animalbodyplan/pages/bodyplan.html. Metazoans. Metazoans. “Animals” Multi-cellular Develop from embryos Divided into two groups based on the presence of a backbone. Body Plans.
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Animal Body Plans Adapted fromhttp://userwww.sfsu.edu/~biol240/labs/lab_16animalbodyplan/pages/bodyplan.html
Metazoans Metazoans • “Animals” • Multi-cellular • Develop from embryos • Divided into two groups based on the presence of a backbone
Body Plans • This can also be described as way an animal is “built” or the architecture of a species • There are some basics features of a body plan that can be used to compare animals • The various body plans we will cover have been shaped through evolution and constraints on the animals
Cambrian Explosion • Most major animal groups around today originated in the precambrian and cambrian era • Explosion of diversity in a relatively short period of time • Some major evolutionary branches occurred around symmetry and multicellularity
Embryology • Protostomes-mouth forms first then the anus during embryological development • Most invertebrate groups • Deuterostomes- anus forms first then the mouth • Can split up cells at 4 cell stage and each will continue to develop into a complete viable organism • Echinoderms and chordates
Symmetry • Def-pattern of arrangement of body parts • Asymmetry- no pattern of symmetry around an axis… • No way to divide the org into similar looking halves • Radial-more than one line of bisection • Bilateral- one line of bisection ie a distinct right and left side • Also typically have dorsal and ventral surface, anterior and posterior surface
Body Cavity • Also called a coelem • Fluid filled cavity found between body wall and digestive tract • Many different types and ways that a body cavity develops • Acts as a hydrostatic skeleton in some less advanced animals
Segmentation • Repeated grouping of parts or compartments • Aids in movement and evolution of appendages • Groups of segments and their appendages have become specialized for a variety of “jobs” among regions ie a division of labor
Cephalization • Def-Having a head • Sensory organs, centralized nervous system and feeding parts are all usually concentrated here • Are there advantages to this arrangement? • Is there a particular kind of symmetry associated with this?
Cephalization Advantage- • Anterior end of a travelling animal will encounter stimuli-food, danger etc… first • Adaptation for burrowing, crawling, swimming • Radial animals tend to be sessile or planktonic- can meet environmental symmetry from all sides • Active animals moving in a distinct direction “meet” the environment from one end and bilateral symmetry fits that lifestyle
WORD BANK • Symmetry • Multicellularity • Pseudocoelem • Protostomedeuterostome • Body cavities and blood vascular system • Tissues • Coelem
Hydrostatic skeleton- skeleton composed of fluid and under pressure in an enclosed body compartment Main skeleton of cnidaria and some worms Gastroderm- layer of tissue producing digestive enzymes