- Quiz: what is the primary benefit of gills? Increases SA for gas exchange- Podcast quiz: what is the primary effect on the oceans of CO2 intake? Decreases pH- Podcast Quiz: what impact does ocean acidification have on oyster reproduction? Reduces reproduction by slowing down growth and increasingmortalityGas Exchange in Marine Invertebrates- Cellular respiration, digestion, and organismal respiration are related how? Digestion provides energy for cellular respiration- Respirationo Physiological process by which oxygen moves into internal environment and carbon dioxide moves out- Respiratory systemo Acts in concert with circulatory system to deliver oxygen and remove CO2o Regulate acid-base balance- Oxygen in the oceano Oxygen relatively constant in sea water Usually 4-6 ppm Lower in some enclosed water bodieso Less soluble in warm watero Oxygen min layer between 40-1000 m depth Min layer created where usage is greater than replenishment by convection, common in highly productive tropical oceans, leads to hypoxic/anoxic zone Oxygen on surface=lots of biomass, photosynthesis- Carbon dioxide in the oceano Very abundant-75% of gas in sea, 93% of all CO2 on planet, only .04% of gas in airo Most dissolved as HCO3-, buffer, pH constanto More protons=more acidic (lower number=more acidic)o What happens if more CO2 is added? - Respiration easy (O2 levels fairly constant), except…o Pelagic animals in oxygen min layero Benthic animals in anaerobic conditions Caused by decomposing sludge and lack of mixing (dead zones)o Animals that migrate through these areaso Active swimmers- fish, mammals (anaerobic conditions in muscles)- Pressureo Definition: unit of force per given areao Gasses exert pressure (molecules move, collide into surfaces which gives pressure)o Partial pressure- pressure a gas would have if it alone occupied a volumeo Total pressure= sum of partial pressures- Atmospheric pressureo Pressure exerted by weight of air on Earth’s surfaceo At sea level= 760 mm Hgo 78% atmosphere is No Oxygen is 21% air; its PP is about 160 mm Hgo 760 x 21/100= 160 mm Hgo Barometer to measure pressure- Partial pressure gradientso Concentration gradients for gases Differ at various places throughout the respiratory circuito Gases diffuse down their pressure gradientso Gases enter and leave the body by diffusing down pressure gradients across respiratory membranes- Fick’s law of diffusiono Diffusion a membrane is: Proportional to SA (positive slope) Proportional to difference in PP across membrane (positive slope) Inversely proportional to distance over which diffusion takes place (negative slope)o Quiz: what adaptations will not cause an organism to increase respiration? Increase SA of respiratory structure, decrease thickness of respiratory surface, max the difference in PP across the respiratory membrane, or decrease the difference in PP across the respiratorysurface (opposite of Fick’s law)- Boundary layero Found next to all solid surfaceso All transport of gas must occur by diffusion across this boundary layero Caused by fluid viscosityo “No slip condition” set up by boundary layer, (pollen on car, no movement of air right on top of car=pollen doesn’t come off)o Water is more viscous, closer and closer to the object- speed of water slows downo High to low concentration (in high they are constantly banging into one another and pushing each other farther away which is why they naturally move to low concentration)- Effects of flow speed on respirationo Flow speed increases, respiration rate increases because the boundarylayer is decreased and then there’s less diffusion to get inside the organism- Large respiratory surfaces needed b/co Boundary layero Water has relatively low oxygen content Oxygen in 1 L water= oxygen in 25 ml air So aquatic organism must move 1 L of water to get 1 ml of oxygen compared to only 25 ml of air to get 1 ml of oxygen for an air breather- Quiz: what happens to SA to volume ratio as diameter of an object gets largero Decreases SA to volume ratio- SA to volume ratioo Animal size increases, SA to volume ratio decreaseso Small, flattened animals can use body surface as their respiratory surfaceo Larger animals have special structure to increase respiratory surface, such as gills or lungsInvertebrate Respirationo Moisture always requiredo Integumentary change (flatworms)o Gills- internal body folds of thin-walled membraneo Internal respiratory surfaces (not in marine) book lungs, tracheal system- Cnidarians-occurs across body wall (Portuguese man-o-war, anemone, hydroid)- Gills – variable in structure and location - Parapodia- similar to gills (clam worms)- Gas exchangeo Parapodia highly vascularizedo Across body wall along Parapodia - Echiura organism- Echinodermso Dermal branchii (papullae)- out-pocketings that do same thing as air sacs, increase SA- Water Vascular systemo Tube feet also used for respiration- Skeleton and dermal branchiio Papullae extended for respiration, drawn in for protection- Respiratory Treeso Muscles generate a tidal flow of oxygenated seawater in and outo Anal breathers- Benefits of out or in pocketings-increases SA- If you were a phylum that was adapting to enhance respiration using gills, what modifications would you make to increase respiratory efficiency under the following scenarios…o In the water? More gills on side, larger gillso After moving to land? - Molluscs: chitonso Gills extend length of body on both sideso Water passes in from sides, across gills, and posteriorlyo Moving from land to watero Molluscs show progression of evolutionary adaptation- Molluscs: abalone (prosobranchs)o Right and left gillso Water passes in through anterior holes, across gills, and out posterior holes- Molluscs: snailo Single gill that is folded to create greater contact between water and gill (=greater diffusion)o Water passes over gill as it circulates through mantle cavity- Molluscs: bivalveso Very large, paired gillso Fold back on self many timeso Used in respiration and feedingo Siphons draw water in (powered by cilia)- Molluscs: cephalopodso Very large, paired gills (except nautilus have 4 gills)o Muscle generated movement of water across gillso Gas exchange across body wall as well (in webbed individuals)- Nudibranch- Molluscs: pulmonates (land snails, with couple primitive intertidal species)o Have internal lungs rather than