Download - 16 - Osmoregulation in Earthworms
in earthwormsOsmoregulation
Osmoregulation• the homeostatic mechanism where
organisms actively regulate the level of water and mineral salts in their bodies or organ systems
• maintain osmotic pressures and keep their fluids from being too concentrated or dilute
Osmoregulators• maintain a more or less stable
internal osmolarity
• Euryhaline - able to tolerate a broad range of environmental salinity
• Freshwater and terrestrial animals
Osmoconformers• organisms whose body fluids are
always isomolar to their environment
• gain and lose water at equal rates - no tendency to gain or lose water
• Stenohaline - limited range of environmental salinities it can live in
• marine animals
Osmoconformers• organisms whose body fluids are
always isomolar to their environment
• gain and lose water at equal rates - no tendency to gain or lose water
• Stenohaline - limited range of environmental salinities it can live in
• marine animals
Lumbricus sp.
niche: soils with variable quantities of water and solutes
exposed to atmospheres of varying moisture content and soils with different ionic concentrations
Leaching, Temperature, Rainfall
Lumbricus sp.
niche: soils with variable quantities of water and solutes
exposed to atmospheres of varying moisture content and soils with different ionic concentrations
Leaching, Temperature, Rainfall
Lumbricus sp.
Because of the wide range of conditions they are subject to,
adaptive mechanisms are important for their survival
Lumbricus sp.
Because of the wide range of conditions they are subject to,
adaptive mechanisms are important for their survival
Lumbricus sp.
Euryhaline osmoregulator that can survive large fluctuations in
environmental osmolarity (2% NsCl)
Internal osmolarity: 0.65% NaCl
Lumbricus sp.
Euryhaline osmoregulator that can survive large fluctuations in
environmental osmolarity (2% NsCl)
Internal osmolarity: 0.65% NaCl
Lumbricus sp.
Major osmoregulatory structures: Metanephridia and Dorsal Pores
Water does not easily diffuse through the skin since it has a
collagenous cuticle layer
Lumbricus sp.
Major osmoregulatory structures: Metanephridia and Dorsal Pores
Water does not easily diffuse through the skin since it has a
collagenous cuticle layer
Metanephridia• with tubules opening to the inside
and outside of the body segment
• obtain fluid from inside of body via nephrostomes
• fluid is filtered, formed under pressure and passed through small openings • molecules larger than certain
size are excluded • fluid is isotonic to coelom,
NaCl removed by active transport system
Metanephridia• with tubules opening to the inside
and outside of the body segment
• obtain fluid from inside of body via nephrostomes
• fluid is filtered, formed under pressure and passed through small openings • molecules larger than certain
size are excluded • fluid is isotonic to coelom,
NaCl removed by active transport system
Metanephridia
Metanephridia
walls of major blood vessels have podocytes! for major filtration in the
coelom
Metanephridia
walls of major blood vessels have podocytes! for major filtration in the
coelom
enter metanephridia via nephrostome as
coelomic fluid (filtrate)
Metanephridia
walls of major blood vessels have podocytes! for major filtration in the
coelom
enter metanephridia via nephrostome as
coelomic fluid (filtrate)
Metanephridia
Metanephridia
narrow ciliated tubule for minor filtration process in
blood vessels
Metanephridia
narrow ciliated tubule for minor filtration process in
blood vessels
Metanephridia
narrow ciliated tubule for minor filtration process in
blood vessels
wide non-ciliated tubule with narrow ciliated
tubules for selective reabsorption of water,
proteins and salts
Metanephridia
narrow ciliated tubule for minor filtration process in
blood vessels
wide non-ciliated tubule with narrow ciliated
tubules for selective reabsorption of water,
proteins and salts
Metanephridia
Metanephridia
transport out of tubule, into surrounding body fluids and prevent loss from
body and wastage
Metanephridia
transport out of tubule, into surrounding body fluids and prevent loss from
body and wastage
Metanephridia
urine excretion - from the bladder to nephridiophore
transport out of tubule, into surrounding body fluids and prevent loss from
body and wastage
Metanephridia
urine excretion - from the bladder to nephridiophore
transport out of tubule, into surrounding body fluids and prevent loss from
body and wastage
Methodology
A situation was given to analyze the presented data
Internal fluid of humidic earthworms is equivalent
to about 0.65% NaCl
Several groups of this species were then
immersed for about 30 minutes with varying
salinities
0 % 0.6 % 0.9 % 1.5 %
0 % 0.6 % 0.9 % 1.5 %
The wet body weights of the worms were nearly similar at the start
0 % 0.6 % 0.9 % 1.5 %
The wet body weights of the worms were nearly similar at the start
0 % 0.6 % 0.9 % 1.5 %
The wet body weights of the worms were nearly similar at the start
After half an hour, wet body weights were measured again
Methodology
Osmoconformers Osmoregulators
• Organisms whose body fluids are always isomolar to their environment
• Gain and lose water at equal rates—no tendency to gain or lose water
• Stenohaline - it lives within a limited range of environmental salinities
• Marine animals
• Maintain a more or less stable internal osmolarity
• Euryhaline - able to tolerate a broad range of environmental salinity
• Freshwater and terrestrial animals
DiscussionResults &
The excretion of Lumbricus terrestris or earthworm is driven by osmosis
0 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
0 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
Body weight decreased greatly after 30 minutes
0 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
Body weight decreased greatly after 30 minutes
Water tends to move out of the earthworm’s body
0 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
Body weight decreased greatly after 30 minutes
Water tends to move out of the earthworm’s body
The environment is hyperosmotic in relation
to the earthworm’s internal fluid (0.65% NaCl)
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
0.6 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
0.6 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
Body weight decreased slightly after 30 minutes
0.6 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
Body weight decreased slightly after 30 minutes
Water tends to move out of the earthworm’s body
0.6 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
Body weight decreased slightly after 30 minutes
Water tends to move out of the earthworm’s body
The environment is hyperosmotic in relation
to the earthworm’s internal fluid (0.65% NaCl)
0.6 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
0.9 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
0.9 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
Body weight increased slightly after 30 minutes
0.9 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
Body weight increased slightly after 30 minutes
Water tends to move inside of the earthworm’s
body
0.9 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
Body weight increased slightly after 30 minutes
Water tends to move inside of the earthworm’s
body
The environment is hypoosmotic in relation to
the earthworm’s internal fluid (0.65% NaCl)
0.9 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
1.5 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
1.5 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
Body weight increased greatly after 30 minutes
1.5 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
Body weight increased greatly after 30 minutes
Water tends to move inside of the earthworm’s
body
1.5 %
0"
1"
2"
3"
4"
5"
6"
7"
I" II" III" IV""
Body%weight%(g)%
Salt%concentra4on%
0"minutes"
30"minutes"
Body weight increased greatly after 30 minutes
Water tends to move inside of the earthworm’s
body
The environment is hypoosmotic in relation to
the earthworm’s internal fluid (0.65% NaCl)
1.5 %
Conclusion
Conclusion
Osmoregulation in earthworms was found to be dependent on the internal fluid osmolarity of the humidic earthworms
Hypotonic Coelomic Fluid
A greater osmolarity of the surrounding fluid than the coelomic fluid would elicit water to move out of the organism resulting to decrease in the body fluid of earthworms
Hypertonic Coelomic Fluid
A lesser osmolarity of the surrounding fluid would cause an increase in body weight since water will rush into the organism