Adapting to Life in the Ocean

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14 Νοε 2013 (πριν από 3 χρόνια και 7 μήνες)

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Adapting to Life in the Ocean


Adaptation
-

process
whereby a population
becomes better suited to its
habitat; takes place over
many generations


Adapting to salinity


Osmotic stress
-

sudden
change in solute
concentration around a cell,
causing movement of water
across its membrane. Under
conditions of high salinity,
water is drawn out of the
cells through osmosis


Osmotic pressure
-

the
pressure that must be applied
to a solution to prevent the
inward flow of water across a
semipermeable membrane



Osmoregulation
-

active
regulation of osmotic
pressure of an organism’s
fluids to maintain water
content; it keeps organism’s
fluids from becoming too
dilute or too concentrated


Osmoconformer
-

match their
body
osmolarity

(salinity) to
their environment


Osmoregulator
-

regulate their
body
osmolarity

by actively
controlling salt
concentrations despite salt
concentration of the
environment



Osmoregulator


Stenohaline
-

restricted to either salt or fresh
water and cannot survive in water with a different
salt concentration than they are adapted to


Euryhaline
-

show a tremendous ability to
effectively
osmoregulate

across a broad range of
salinities


Adapting to temperature


Organisms lose heat more quickly in water than in
air


Adaptations


Ectotherm
/
poikilotherm
-

internal body temperature
varies along with the ambient environmental
temperature; dependent on environmental heat
sources; relatively low metabolic rates (most fishes and
reptiles)


Adaptations


Endotherm
-

internal body temp. varies but is
elevated above ambient environmental temps as a
result of metabolic heat production (some fishes)






Homeotherm
-

internal body temp. remains
relatively constant despite the ambient
environmental temp. (birds and mammals)


Adapting to viscosity


Viscosity


describes a fluid’s internal resistance to
flow; water is “thin”, having a lower viscosity, while
honey is “thick”, having a higher viscosity


Drag


refers to forces that oppose the relative motion
of an object through a fluid


Hydrodynamic adaptations


Fusiform
-

body shape characterized by being tapered at both
the head and the tail


Fish secrete mucous from glands under their skin; reduces
drag by 60%


Sharks have
denticles

on their skin that cause the water to
form a thin film that reduces drag in much the same way as
the slimy mucous


Adapting to pressure


Hydrostatic pressure
-

press. At a given depth in a
static liquid is a result of
the weight of the liquid
acting on a unit area at
that depth plus any
pressure acting on the
surface liquid


Pressure increases 1
atmosphere (or bar) for
every 10 meter or 33
ft

of
depth in ocean water


Adaptations


Light skeletons and water
muscles


Fluid filled body cavities
rather than gas
-

filled
spaces


Piezophile
-

organism that
thrives at high pressures
(deep sea bacteria or
acrhaea
)


Buoyancy
-

upward force,
caused by fluid pressure
that keeps things afloat


Archimedes’ principle
-

any
object, wholly or partially
immersed in a fluid, is
buoyed up by a force equal
to the weight of the fluid
displaced by the object


Adaptations


Small size reduces sinking
(plankton)


Using fins as hydrofoils
(sharks)


Using low

density organic
compounds (oil) or body
fluids (plankton, sharks)


Gas
-

filled bladders (bony
fishes)