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