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Unformatted text preview: Class Clitellata Clitellata Oligochaetes, Leeches and allies Have a Clitellum Have Clitellum Specializations in reproduction and reproductive organs Direct Development Direct Subclass Oligochaeta Oligochaeta few setae no parapodia terrestrial, fresh water, marine hermaphroditic Dissected in lab Hermaphroditic Outcross Mutually copulate Lay egg capsule Regeneration - species specific Class Hirudinoidea Hirudinoidea Specialized No setae No parapodia Hermaphroditic Reduced segmentation Predators or Ectoparasites Can be important human parasites Many are predators lay egg capsules, even when aquatic Do not regenerate Use suckers for locomotion and attachment other relatives Allies of Annelids Allies Recently placed in Phylum Annelida Recently Annelida Class Polychaeta Class Polychaeta Family Siboglinidae Family Siboglinidae Previously - two separate Phyla Previously Pogonophora - beard worms Pogonophora Vestimantifera - rift worms Vestimantifera Pogonophora No gut Thin, < 1 mm diameter Live in tubes Anterior tentacles with pinnules Anterior pinnules Posterior - only evidence of Posterior only segmentation, chaete chaete Vestimantifera Vestimantifera Hydrothermal vent worms Transitory guy in juveniles no gut in adults Trophosome - houses symbiotic Trophosome chemosynthetic bacteria chemosynthetic bacteria Blood with extremely high affinity for O2 Riftia Riftia Skeletons Role of skeleton – Provide 3-D support, structural support Forces to antagonize muscles Muscles contract - shorten Require external force to extend Types of skeletons: Types Struts & Supports Exoskeletons Soggy Skeletons ! Hydroskeletons Soggy Hyroskeleton Hyroskeleton ! internally pressurized structures Fluid incompressible Fluid ! Pressure x Volume = constant Hydrostatic Skeleton – fluid pressure used for support and to antagonize muscles Fluids are incompressible Do not change volume when forces are applied Hydrostatic – internal fluid pressure Hydrostatic
Requirements: fluid-filled closed chambers Internal pressures generated by muscle contractions maintain the shape used for movement fluid pressure will extend longitudinal muscles Circular muscles contract 1 ml 1 ml 1 ml Apply a force Fluid moves until pressure equalized NOTE: Power point will not let NOTE: me print equations and greek me letters or special symbols to a pdf file. This file has greek letters (italics) in equations written and special symbols as text. Please cross check with your notes from class for equations equations Spherical or Cylindrical Sphere: Pressure on walls uniform Sphere: Stress = sigma Stress sigma sigma = F (force) A (area) sigma = pR pR A R = radius t = wall thickness p = internal pressure A = area of vessel wall area = 2 pi R t pi Problems with being a sphere? Problems most organisms ! cylindrical cylindrical longitudinal and radial pressure longitudinal Longitudinal stress: Longitudinal sigmaL = F = pR sigma pR A 2t Hoop stress: sigmaH = F = pR pR A t sigmaH = 2 x sigmaL sigma ? Prevent Blow-outs? Prevent tension resisting fibers in membrane tension for reinforcement for ? Arrangement Of Fibers? long. & circ. wound – can’t move Helically wound – Helically continuous reinforcement in continuous all directions all Do angles make a difference? Do problems ! balance hoop & long. stress problems balance (sigma H = 2 sigmaL ) sigma ! volume control volume Fiber winding angle: 54 degrees 44 seconds 54 Balance sigmaH & sigmaL Balance sigma sigma Maximal Volume Maximal Design Principles: Design 1. Thin walled cylinders- reinforce against EXPLOSION and reinforce EXPLOSION and BUCKLING by cross helically wound fibers. BUCKLING by cross 2. In pressurized fiber wound cylinder, sigmaH & sigmaL are balanced at 54 degrees 44 seconds. sigma at 54 3. Open cylinders attain maximal vol. at 3. 54 degrees 44 seconds. 54 4. flexible cylinder most effectively reinforced against 4. IMPLOSION by thikening body wall IMPLOSION by intinternal circumference thickening LIMP WORMS: LIMP Nemerteans, flatworms, etc. - flattened cylinders - fibers 40 degrees to 70 degrees range fibers degrees - contract longitudinal muscles !turgid, short, fat - contract circular muscles ! turgid, long, skinny STIFF WORMS: Nematodes, Nematomoprphs Nematodes, Nematomoprphs Circular in Cross section, strong cuticle, Circular only longitidunal muscles muscles Ascaris - ~75 degrees ~75 degrees muscles contract !shorten, stiffer SQUID MANTLE: SQUID only circular muscles fibers 25 degrees fibers degrees contraction extends mantle, reduces volume ! jet propulsion CNIDARIA: loose fibers, helical angles hydra tentacles - ~10 degrees hydra ~10 degrees Echinoderm feet, Shark skin Can combine hydrostat with hard elements Can e.g., aciculi e.g., Role of cuticle Role Fiber winding Stretchy or Not Helically wound fibers Helically allow stretch - very strong, reinforcement allow Fixed length fibers - strong but do not Fixed strong allow for movement allow Who uses hydrostatic skeletons? Who Of the phyla we have considered - who uses hydrostatic skeletons?? Of Porifera ? Cnidaria ? Placozoa ? Ctenophora ? Platyhelminthes ? Rhombozoa ? Orthonectida ? Nemertea ? Annelida ? Nematoda ? Nematomorpha ? Kinorhyncha ? Polychaeta? Clitellata? Reynolds Numbers & Hydrodynamics Reynolds Gas or Liquid Fluids: Newtonian fluids Newtonian Have no memory of previous shape Properties are the same at different velocities (we will talk later about some (we biological non-Newtonian fluids) biological Never act like solids Fluids resist moving = viscosity viscosity No Slip Condition No All movement with fluids No movement at boundary with solid => Velocity Gradients Boundary Layer Boundary Layer Distance from a solid surface until in main-stream velocity of the fluid Velocity Gradient on a flat plate Velocity put a plate into the flow Water Flow Regimes: Water LAMINAR - regular, smooth, orderly TURBULENT - irregular, erratic Osborne Reynolds (1842 - 1912) Interested in flow of fluids through pipes Pipe flow Pipe 1) fluid viscosity, fluid density 2) pipe diameter 3) flow speed 3) Laminar - e.g. pouring honey nice, orderly flow Turbulence Flow visualization Laminar Turbulent Transition from Laminar to Turbulent abrupt Transition Transition occurs when a dimensionless composite of these three factors approx. 2000. approx. 2000. This dimensionless composite = The Reynolds number (Re) Single Best Index of Flow Character Re is an indicator of the Relative importance of Relative Intertial Forces and Viscous Forces Forces Viscous Favors Turbulence Prevents Turbulence Equality of the Re for two flows ==> The physical character of the flows will be the same ...
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This note was uploaded on 01/27/2010 for the course BIO 37282 taught by Professor Padilla during the Fall '10 term at SUNY Stony Brook.
- Fall '10