4c Flashcards
(72 cards)
Organisms that can control ion exchange well with their enviroment have
effective body isolation (impermeable skin, scales, or exoskeletons)
they can control ion exchange with their enviroment
ex. teleost fish, sharks, crabs
Organisms that can control ion exchange poorly with their enviroment have
they have highly permeable soft bodied organisms
they struggle with ion regulation bc ions and water passively flow across their bodies
ex. jellyfish, sponges, sea anemones
explain how crabs are good ion regulators and one specific crab species
they can tolerate a variety of different salinties using combination of physiological, behavioural, molecular mechanisms to regualte ions (NA+, K+, Cl-, and Ca2+)
main organs involved in regulation are the gills (the primary ion exchange site)
ex. the marine crab or Carcinus maenas
- has specialised cells called the chloride cells (ionocytes) which actively pump out excess Na+ and Cl-
- b/c they constantly drink seawater to compensate for water losses due to osmosis with the enviroment
-> intake of water brings also extra salts that they dont need
crabs in brackish water ex, eriocher sinesisis, what mechanism do they use to combat ion loss
they use gills.
the gills are used to absorb ions from the water
this compensates for ion loss. the external enviroment is less salty than their body
6 points
explain how bony fishes are good ion regulators
they have physical barriers that prevents passive diffusion of ions in or out - thick epithelial layers and scales
barriers that reduce uncontrolled ion diffusion - they rely on on a targeted ion transport approach to actively pump ions in or out
bony fishes cant actively regulate the composition of their body fluids. Osmosis causes a continual loss of freshwater through gills and urine to the external enviro
constant drinking of seawater brings in extra salts that are not needed
so , they are actively excreted so that the animal can maintain an overall lower (hyposmotic) salt content in their body
- THIS IS ACHIEVED BY GILL AND ION concentrated urine excretion
are poor ion regualators osmoconformers?
yes
they match their internal ion levels to that of seawater
how can poor ion regulators avoid osmotic stress
by using cell volume regulation to avoid osmotic stress
in poor ion regulators
how does cell volume regulation
they rely on osmolytes - which are small non toxic molecules that function to balance osmotic pressure w out disrupting thr orgs cellular functions
in poor ion regulators
what do osmolytes do
3 points
they help balance water inside cells
replace inorganic ions like Na + , cl- to avoid disrupting cellular chemistry
dont interfere w enzyme or protein function
what are some ex of common osmolytes used by inveterbrae, hagfishes
free amino acids - glycine, taurine
these free amino acids have little function on protein function
what are some ex of common osmolytes used by seaweeds, and unicellular algae
sugars and polyols - glycerol, mannitol, sucrose
when inc salinity in environment…
more osmolytes or less osmolytes?
cells synthesize more osmolytes -> cells retain water
when dec salinity in environment
osmolytes broken -> prevents bursting due to excess water inflow
advantage of osmolytes
don’t interfere with enzyme function
2 methods of cell volume regulation in poor ion regulators
- ion resdistribuition
- osmolytes
what is ion redistribuition
it is when cells can temporarily shift ions like K+, Cl- between cellular compartments
2 thing
why does ion regulation work for poor ion regulators
they live in relatively stable marine enviroments - salinity changes are graudal
using osmolytes/ion redistri are both energy effiecient process bc no active pumping across the body surface is required
Why Oxygen Matters:
Oxygen is essential for ATP production, which provides energy for all cellular functions.
Some marine environments naturally have very little oxygen:
what are they - iso
Intertidal zones at low tide
Sediments
Oxygen minimum layers in the water column
why low oxygen in oxygen minimum layers in the water coloumn
These are depths in the ocean where oxygen is very low due to:
High organic matter decomposition
Poor mixing or oxygen supply
why low oxygen in sediments
Water within mud/sand can be anoxic (oxygen-free), especially deeper down where oxygen can’t diffuse easily.
why is it low oxygen at Intertidal zones at low tide
Water recedes → animals like clams or snails may be exposed to air or water with little oxygen.
2 things
what does Seasonal hypoxia lead to
Some areas experience seasonal oxygen drops, leading to:
Hypoxic zones (low oxygen)
“Dead zones” where oxygen is too low to support most marine life (like fish kills — shown in the bottom image)
