Consider the molecular views of an Al strip and Cu2+ solution. Draw a similar sketch showing what happens to the atoms and ions after the Al strip is submerged in the solution for a few minutes.
Adaptations to Seawater ● Homeostasis constancy in the internal environment ● Enantiostasis constancy in the internal functions ○ Things can change, but the functions are maintained ● How is metabolic rate measured ○ Amount of oxygen used or CO2 produced ○ Ignores the contribution of anaerobic respiration ● Salinity ○ Can change rapidly which affects organisms’ distribution ○ Can directly affect organisms through osmosis and diffusion ○ Organisms regulate organic and inorganic cellular constituents to adjust salinity ○ Body fluids of fish are ⅓ the concentration of their environment ○ Stenohaline organisms that live in a small range of salinities ○ Euryhaline organisms that live in a wide range of salinities ○ Internal environments of almost all invertebrates differ from their external environments in ionic and osmotic characteristics ■ This results in ionic and osmotic gradient ○ Most invertebrates have equal concentrations of cell constituents to seawater ■ They don’t osmoregulate ○ 817% of energy is osmoregulation ○ Freshwater bony fish ■ Internal salinity (osmolality) of 200300 mOsm/kg ■ External salinity of 140 ■ Water enters and solutes exit ● Excess water through urine ● Get more solutes through active uptake in gills and eating ○ Saltwater bony fish ■ Osmolality of 300500 ■ External salinity of 1000 ■ Solutes enter and water exits ● They drink 310 times as much water as freshwater fish ● Ions Na and Cl are eliminated in chloride cells in gills ● Diatomic ions are eliminated through kidneys ○ Hagfish the only vertebrate that is isosmotic ○ Fish moving between fresh and saltwater ■ Fresh to saltwater is harder because the salinity gradient is much larger ○ Sharks and rays ■ Nearly isosmotic; slightly hyperosmotic ■ Little water movement, but still ion regulation ● Each ion moves independently of other ions ● About 500 ions are supplied from water ● The other 500 come from osmolytes urea and TMAO ○ Urea a waste product; highly soluble and uncharged ○ Costly to synthesize, easily lost because of its diffusibility ○ Poisonous in large quantities TMAO fixes that ● Rectal glands remove salt from blood ○ What about freshwater sharks and rays ■ They don’t produce as much urea; ex: bullshark ● But they need some of it for when they are in saltwater ■ The freshwater ray lost almost all of its urea because it is landlocked ○ Marine reptiles and birds ■ Excrete through kidneys ● Temperature ○ Affects: metabolisms, enzymatic reactions, membrane properties, activity, growth, distribution, digestive rates, behavior, health ○ Ectothermic body temperature is a product of the external environment ○ Endothermic body temperature is determined by the metabolic furnace ○ Poikilothermic changing body temperature ○ Homeothermic consistent body temperature ○ Mammals, birds, some turtles, and two groups of fishes (Scombridae and Laminidae) are endotherms ○ Why are most aquatic animals ectotherms ■ Water has a high specific heat and high thermal conductivity ■ 3000 times the capacity as air for absorbing heat ○ Endotherms ■ Mammals blubber and hair/fur ■ Birds feathers ■ Fish countercurrent heat exchange in gills, swim bladder, and heater organs ● Scombrid tuna and Lamnid sharks ○ Vessels close to skin surface ○ Run from warm core to outer vessels (cold) ○ Red muscle ■ For sustained activity ■ Cruising ■ Lots of blood present; myoglobin ■ Use oxidative metabolism ○ White muscle ■ Burst performance ■ Uses mostly glycogen ■ Respire anaerobically
