16 - Osmoregulation in Earthworms

(1)

in earthworms

(2)

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

(3)

Osmoregulators

•

maintain a more or less stable

internal osmolarity

•

Euryhaline - able to tolerate a

broad range of environmental

salinity

•

Freshwater and terrestrial

(4)

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

(5)

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

(6)

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

(7)

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

(8)

Lumbricus sp.

Because of the wide range of

conditions they are subject to,

adaptive mechanisms are

important for their survival

(9)

Lumbricus sp.

Because of the wide range of

conditions they are subject to,

adaptive mechanisms are

important for their survival

(10)

Lumbricus sp.

Euryhaline osmoregulator that can

survive large fluctuations in

environmental osmolarity (2% NsCl)

Internal osmolarity: 0.65% NaCl

(11)

Lumbricus sp.

Euryhaline osmoregulator that can

survive large fluctuations in

environmental osmolarity (2% NsCl)

Internal osmolarity: 0.65% NaCl

(12)

Lumbricus sp.

Major osmoregulatory structures:

Metanephridia and Dorsal Pores

Water does not easily diffuse

through the skin since it has a

(13)

Lumbricus sp.

Major osmoregulatory structures:

Metanephridia and Dorsal Pores

Water does not easily diffuse

through the skin since it has a

(14)

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

(15)

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

(16)

(17)

Metanephridia

walls of major blood

vessels have podocytes! for major filtration in the

(18)

Metanephridia

coelom

enter metanephridia via

nephrostome as coelomic fluid (filtrate)

(19)

Metanephridia

coelom

enter metanephridia via

nephrostome as coelomic fluid (filtrate)

(20)

(21)

Metanephridia

narrow ciliated tubule for

minor filtration process in blood vessels

(22)

Metanephridia

(23)

Metanephridia

wide non-ciliated tubule

with narrow ciliated tubules for selective

reabsorption of water,

(24)

Metanephridia

wide non-ciliated tubule

with narrow ciliated tubules for selective

reabsorption of water,

(25)

(26)

Metanephridia

transport out of tubule, into

surrounding body fluids and prevent loss from

(27)

Metanephridia

transport out of tubule, into

(28)

Metanephridia

urine excretion - from

the bladder to nephridiophore transport out of tubule, into

(29)

Metanephridia

urine excretion - from

the bladder to nephridiophore transport out of tubule, into

(30)

(31)

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

(32)

0 %

0.6 %

0.9 %

1.5 %

(33)

0 %

0.6 %

0.9 %

1.5 %

(34)

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

(35)

(36)

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

(37)

Discussion

(38)

The excretion of Lumbricus terrestris or earthworm

is driven by osmosis

(39)

0 %

0" 1" 2" 3" 4" 5" 6" 7"

I" II" III" IV"" Body%weight%(g)%

Salt%concentra4on%

0"minutes" 30"minutes"

(40)

0 %

0" 1" 2" 3" 4" 5" 6" 7"

0"minutes" 30"minutes" Body weight decreased

(41)

0 %

0" 1" 2" 3" 4" 5" 6" 7"

greatly after 30 minutes

Water tends to move out of the earthworm’s body

(42)

0 %

0" 1" 2" 3" 4" 5" 6" 7"

The environment is hyperosmotic in relation to the earthworm’s internal

(43)

0" 1" 2" 3" 4" 5" 6" 7"

(44)

0" 1" 2" 3" 4" 5" 6" 7"

(45)

0" 1" 2" 3" 4" 5" 6" 7"

slightly after 30 minutes

(46)

0" 1" 2" 3" 4" 5" 6" 7"

(47)

0" 1" 2" 3" 4" 5" 6" 7"

The environment is hyperosmotic in relation to the earthworm’s internal

fluid (0.65% NaCl)

(48)

0" 1" 2" 3" 4" 5" 6" 7"

(49)

0" 1" 2" 3" 4" 5" 6" 7"

(50)

0" 1" 2" 3" 4" 5" 6" 7"

0"minutes" 30"minutes" Body weight increased

(51)

0" 1" 2" 3" 4" 5" 6" 7"

Water tends to move inside of the earthworm’s

body

(52)

0" 1" 2" 3" 4" 5" 6" 7"

body

The environment is hypoosmotic in relation to

the earthworm’s internal fluid (0.65% NaCl)

(53)

0" 1" 2" 3" 4" 5" 6" 7"

(54)

0" 1" 2" 3" 4" 5" 6" 7"

(55)

0" 1" 2" 3" 4" 5" 6" 7"

(56)

0" 1" 2" 3" 4" 5" 6" 7"

body

(57)

0" 1" 2" 3" 4" 5" 6" 7"

body

The environment is hypoosmotic in relation to

the earthworm’s internal fluid (0.65% NaCl)

(58)

(59)

(60)

Conclusion

Osmoregulation in earthworms was found to be dependent on the internal fluid osmolarity of the humidic

(61)

(62)

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

(63)

(64)

Hypertonic Coelomic Fluid

A lesser osmolarity of the

surrounding fluid would cause an increase in body weight since water will rush into the organism