Chapter 28: Water & Salt Environment

replacement of water

1. drink seawater (gains NaCl ions from ocean) 2. low excretion of urine (HYPERosmotic)

modes of water loss

1. integument 2. respiration 3. excretion (evaporative water loss is integument and respiration combined)

passive salt and water exchanged determined by:

1. magnitude of osmotic and ionic gradients 2. permeability of animal's outer body 3. surface area

marine elasmobranch fish (sharks, rays)

HYPERosmotic and hypoionic osmotic pressure is slightly higher than saltwater (less ions in body but maintain hyperosmotic pressure, through urea and rectal salt glands that excrete)

all freshwater fish are ________

HYPERosmotic regulators (higher ion concentration than freshwater environment)

marine teleost fish are _______ to seawater

HYPOosmotic (less ions inside body than inside) (think of ocean: a desiccating/dry environment)

reptiles and birds

HYPOosmotic regulators (water loss and salt loading through salt glands)

Do fish drink water?

No, water is already diffusing into fish

excretion of Cl is _____

active

Freshwater animals transport sodium into their body from the environment via

active transport

marine invertebrates

are isosmotic to seawater (octopi, sponges, annelid) ACTIVE uptake of ions from seawater

hyper-isosmotic regulators

blue crab, amphipod, carp (first HYPER because it is above the line, then isoosmotic)

If a freshwater fish takes in a quantity of water from its dilute environment by osmosis, the osmotic pressure in its plasma will tend to (Thought process: what would happen after a while?)

decrease (after awhile it will equalize)

more lipids in integumentary areas

equals LESS water loss

more SA

equals MORE evaporative water loss

freshwater crabs maintain higher osmotic pressure?

excrete isosmotic urine

(Freshwater fish) How do fish handle an influx of water?

excretion (hyperosmotic regulators) ACTIVE ion uptake (requires ATP)

Which of the following animals is NOT a hypoosmotic regulator?

freshwater fish (hyper)

compare and contrast marine and freshwater fish. What are their environments like? How do they osmoregulate? (short answer)

freshwater: hyperosmotic, water DIFFUSES into fish, gills: MRC (mitochondria rich cells =) active UPTAKE of Na and Cl low osmolarity in environment marine: water DIFFUSES OUT, Cl actively transported OUT high osmolarity in environment hypoosmotic regulators

water turn over is _______ in ______ than in ectotherms

higher, endotherms

low salinities (hyper-hypoosmotic)

hyperosmotic

low salinities (hyper-isosmotic)

hyperosmotic

high salinities (hyper-hypoosmotic)

hypoosmotic

arthropods are

isosmotic

high salinities (hyper-isosmotic)

isosmotic

higher temperatures

lose more water because lipids lose their form

trout living in very "soft" freshwater have what kind of cells in gills?

mitochondria rich cell

hard water contains _____ minerals.

more

excretion (dry environment)

more HYPERosmotic (greater concentration)

marine mammals

most concentrated urine of all species hypoosmotic pressure salt glands but answer is unclear

hagfish

only vertebrate that is isosmotic to seawater

Gaining water (largely through diffusion) determined by

passive transport

respiratory water loss

perspiration (dogs and noses)

exhaling cooler air

reduces body temperature, lose LESS water vapor (think back to hot environments=more water vapor loss and vice versa) **MINIMIZE WATER LOSS

weight specific water loss is _______ between large and small animals

the SAME

freshwater fish (where do water and ions flow?)

water diffuses INTO fish active UPTAKE of Na and Cl

marine fish (where do water and ions flow?)

water diffuses OUT of fish ACTIVE EXCRETION of CL