Difference between ECO and Endotherms, Homeotherms and heterotherms and Osmoregulation, osmoconformer and osmoregulatory
Difference between ECO and Endotherms:
Ecotherms derive
most of their derive most of their body heat from the environment rather than
from their own metabolism. They have low rates of metabolism and are poorly
insulated. In general, reptiles, amphibians, fishes and invertebrates are
ectotherms, although few reptiles, insects and fishes can raise their internal
temperature. Eclotherms tend to move about the environment and find places that
minimize heat or cold stress to their bodies. Birds and Mammals are endotherms
because they obtain their body heat from cellular processes. A constant source
of internal heat allows them to maintain constant core temperature, despite the
fluctuating environmental temperature.
Most endotherms
have bodies insulated by fur or feathers or hair and relatively large amount of
fat.
Homeotherms and heterotherms:
Most endotherms
are homeotherms (maintain constant body temperature) and most ectoderms are
heterotherms (have variable body temperature). Some endotherms vary their body
temperatures seasonally (e.g. hibernation), others vary it on daily basis.
Some humming
birds and mammals (e.g. shrews) can only maintain high body temperature for a
body mass so small that they cannot generate enough heat to compensate for the
heat lost across their large surface area. Humming birds must devote much of
the day to locating and sipping nector (a very high calorie food source) as a
constant energy source for metabolism. When not feeding, humming birds rapidly
run out of energy unless their metabolic rates decrease considerably. At night
humming birds enter a sleep like state called daily torpor and their body
temperature approaches that of cooler surroundings, some bats also undergo
daily torpor to conserve energy.
Osmoregulation, osmoconformer and
osmoregulatory:
Excretion of
nitrogenous is usually associated with the regulation of water and solute
(ionic) balance by physiological process called osmoregulation. It is necessary
for animals in all habitats. If the osmotic concentration of the body fluids of
an animal equals that of the medium (animal’s environment) animal is an
osmoregulator. When the osmotic concentration of environment changes, so does that
of animals’ body fluids. This type of osmoregulation is not efficient and has
limited the distribution of those animals using it. In contrast an animal that
maintains its body fluids at different osmotic concentration from that of its
surrounding environment is an osmoregulatory.
(45) Protonephridia:
Earliest type of
nephridium to appear in the evolution of animals was protonephridium. Among the
simplest of protonephridia are flame cell systems e.g. in rotifers, some
annelids, larval molluscs and some flatworms. Protonephridial excretory system
is composed of network of excretory canals that open to the outside of the body
through excretory pores. Bulb like flame cells are located along the excretory
canals. Fluid filters into flame cells from surrounding interstitial fluid and
beating cilia propel the fluid through the excretory canals and out of the body
through the excretory pores. Flame cell systems function primarily in
eliminating excess water.
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