Osmoregulation = keeping water and salt balanced in the body Question 1: why is this important – Come up with three reasons Question 2: What water and salt problems do the following organisms face? – Freshwater fish – Marine fish – Marine birds – Marine mammals Question 3: How might each group solve those problems?

Definitions Solute Solvent Osmosis Osmotic Pressure Osmolarity Hyperosmotic Hypoosmotic Osmoconformer Osmoregulator

Solutes are dissolved particles in solution (any type)

Water always moves from an area of low osmotic pressure to an area of high osmotic pressure osmotic pressure: Osmosis:

Freshwater teleosts: Osmoregulators Problems? Solutions? Hyperosmotic to environment

Active transport of Na+ into animal 2 K+ 3 Na+ ATP Active transport of salts via skin: Cl- Cl- follows passively (electric gradient)

Cl- Na+ Marine Strategies Cartilaginous fish

Marine teleosts: Osmoregulators (hyposmotic to environment) Problems? Solutions?

How do they get rid of huge salt load? Marine reptiles and birds… seawater Salt glands! Nasal fluid urine

Salt glands salt is excreted from the gland to outside the body more concentrated than sea water! mechanism is same in marine reptiles -but salt gland is in different places Na+ mOsm seawater470 sea snake620 sea turtle690 Marine Iguana gull cormorant petrel

How do mammals make concentrated urine? Each nephron has a loop of Henle: nephron loop of Henle

Cortex Outer Medulla Inner Medulla Loop of Henle mammalian nephron: Na+ mOsm

Marine Mammals 1. Long loop of henle in the kidney --concentrated urine --less water lost with waste 2. Diet --carnivores, eating mostly vertebrates --vertebrates have lower osmolarity 3. Absence of sweat glands Several Adaptations:

Nitrogenous Wastes affect Water Balance ProteinsNucleic acids Nitrogenous waste products UREAAMMONIA URIC ACID

Excretion ammonia urea uric acid Teleost fish chondrichthyes Birds and reptiles mammals Amphibiansreptiles % of urinary nitrogen SpeciesHabitatAmmoniaUreaUric Acid Red-eared sliderFreshwater Forest hinge-back tortoise Moist Terrestrial Mediterranean spur- thighed tortoise Dry terrestrial Texas tortoiseDesert Tortoises and Turtles: Teleost fishAmphibians reptiles

Terrestrial summary Water in: – Food and drink – Metabolic water Water out: – excretion – Evaporative water loss Adaptations in the desert? – Extended loop of henle – Reduced evaporative water loss (gain in camel nose) – High dehydration tolerance