Littorina Littorea (common periwinkle) and how their muscles foot work
Created | Updated Sep 14, 2002
Well this was the introduction to my Biology A level course work, s if it helps u, ur welocome. Got soooooooooo fed up <cross> of not being able to find any info online, i'll thought i'd put it there my self :) .When u get to the muscle bit its not very good and probably wrong <blue> SORRY. Did the whole thing over night. don't know how to put diagrams in or even if u can, so theres links instead. Its amazingly dry (boring) incase u had not guessed by now.
The common Periwinkle (Latin name – Littorina Littorea) is part of the prosobranch gastropods family, which also includes Calliostoma euglyptum and Ilyanassa obsolete9. They are found on most coasts of Britain except on extremely exposed shores. They are found mostly on rocks and cliffs but also muddy or sandy areas such as mud flats and estuaries where sea and fresh water meet, due to the periwinkles high tolerance to saline waters of up to 15m.
The maximum length of a periwinkle is around 4 cm, fertilisation is internal and the sexes are separate. For nutrients the Common Periwinkle slides along a surface, such as a rock pool, consuming microorganisms, using the foot at the bottom of the shell for movement. This normally takes the form of regular, continuous gliding. The foot is composed of string muscles, and is connected to the head, which has a mouth and sensory organs (used to gather information and food). The under surface of the foot is known as the sole, which is surrounded by a foot fringe (like a border). The soleslides over a thin layer of mucous secreted by a gland situated in the front part of the foot4. This is one of reasons why dehydration is such an important issue for Common Periwinkle.
One of the greatest threats faced by periwinkles are predators. Its highest defence against this threat is its shell composed of mostly Calcium carbonate in a protein matrix. This shell is composed of three layers:
1. The outer organic periostracum layer
2. The middle calcareous layer
3. The inner calcareous nacreous layer
These three layers provide a quite strong barrier and dissuade predators from bothering to catch them, instead going for easier targets The is shell secreted by a tissue called the mantle and is only connected to the Periwinkles body at one point, where the columellar muscle attaches its self to the end spindle of the shell (as seen below3). If it looses its shell it will most certainly die due to predators and dehydration.
However the greatest problem is dehydration, which the shell’s structure helps to prevent. Dehydration is such a treat because Periwinkles need water for many of their living processes and are constantly using it. For example their movement requires mucus-containing water to allow them to slide along surfaces in order to collect food.
To protect itself the Periwinkle attaches its self to a solid surface (e.g. rocks/cliffs) when the tide withdraws. It does this by retracting from outside and dispensing a type of mucus which dries and hardens in the air, producing an air proof seal to limit evaporation and transpiration rates. The thick skin which covers the back and sides of the Periwinkle’s body also contains large numbers of mucous glands. Mucous released in to the network of furrows between the tubercles (small bumps on the skin) spreads over the whole of the animal's body, so that the evaporation of water from the animal's skin is reduced4. The Common Periwinkle may also attach itself to damp sea weed algae using it’s foot, this is how the periwinkles will attach them selves to the petri dishes using their foot while they are outside of their shells. Both methods also protect against rough wave action and being picked up and crushed against rocks while they are dormant or out feeding.
Below is a Semi-schematic diagram illustrating some of the external anatomical features of the marine prosobranch gastropod Littorina littorea. The animal has been removed from the shell and is viewed from the left hand side6 and has a key below.
http://www.cnsm.csulb.edu/programs/nsfs/research/drmason/gastropod/diagram_prosobranchia.html
The columellar muscle in Periwinkles is a flat muscle, which starts at the coil of the shell and ends at the operculum. The columellar muscle is mostly made of a densely packed three- dimensional muscles and connecting tissue fibres9. The fibre arrangements are not the same through out the muscle; there are three regions, which blend into each other. The columellar muscle at the spindle of the Periwinkle is made up of mostly longitudinal muscle fibres with few fibres running along the columellar or transverse fibres, and no slanting fibres. The middle part of the columellar muscle in the zone before the head consists of longitudinal, fibres running along the columellar, and transverse fibres wrapped by two opposite layers of slanting fibres. The third region of the columellar muscle extends through the foot and includes longitudinal, transverse, and fibres that run along the columellar and out of the shell with a layer of slanting fibres on the back surface. A narrow line of spherical spaces divides the columellar muscle into dorsal and ventral halves in this zone. Each zone performs a different function to the Periwinkle. This dense three-dimensional muscle is what makes the snails hold so strong compared to its relatively small volume unlike animal cylindrical muscles.
Muscles are the only issue in the body, which may contract, this means it may change its length or become tense, they take up 40% to most animals. The main muscle type used in Common Periwinkles is smooth muscle. It is made up of many slender muscle fibres. Every Muscle fibre contains a single cell with a nucleus and cytoplasm about 0.2 mm long, the cytoplasm contains the protein Myofibrils that are responsible for muscle contraction as is the protein Actin. These two proteins together are the basis of, muscle contraction. This happens by thick (Actin) and thin (Myofibrils) filaments sliding between each other, the thick filaments are held together at the M line and the Thick elements are held together at the z line, both sets move as a unit. There are many theories on how muscles contract but the most believed on is the "sliding filament" hypothesis. This happens because thick and thin filaments are in a pattern in the sarcomere. Each thick filament is surrounded by 6 thin filaments. A large protein molecule called Titin connects these thick filaments to the Z disk and maintains the order of thick and thin filaments. Titin is also responsible for the muscle's resistance to stretching after a certain threshold.
For the columellar muscle to contract the following line of events must occurs in order. The events, which happen before the contraction, are started by the central nervous system, either as voluntary activity from the brain or as reflex activity from the spinal cord. A motor neuron in the ventral horn of the spinal cord is activated, and an action potential passes outward in a ventral root of the spinal cord. The axon branches to supply a number of muscle fibres called the motor unit; the action signal is sent to the motor end plate on each fibre. When it reaches the motor end plate, the action causes the release of packets (quanta) of acetylcholine into the synaptic clefts on the surface of the muscle fibre.
Acetylcholine causes the electrical resting signal under the motor end plate to change, and this then initiates an action signal, which passes in both directions along the surface of the muscle fibre. At the end of each transverse tubule onto the muscle fibre surface, the action signal spreads inside the muscle fibre. At each point where a transverse tubule touches part of the sarcoplasmic reticulum, it makes the Sarcoplasmic reticulum release Ca+ ions. The calcium ions result in movement of Troponin and Tropomyosin on their thin filaments, and this enables the myosin molecule to bridge itself, causing contractions.
The contractions then must be stopped; this is done by acetyl cholinesterase, which break down Acetylcholine. So that no more signals may be sent along the muscle. The sarcoplasmic reticulum then stops releasing calcium ions and gathers up the ones it released earlier. With no calcium ions a change in the configuration of Troponin and Tropomyosin then blocks the action of the myosin molecule heads from bridging, and contraction stop. Gravity then helps to pull the muscle back to its original shape.
Biography
Internet sites
1. www.sportesport.it/ shellsGA28.htm
2. http://www.vattenkikaren.gu.se/fakta/arter/mollusca/prosobra/littlitt/littli4e.html
3. http://oceanlink.island.net/oinfo/intertidal/mollusca.html
4. http://www.geocities.com/Heartland/Valley/6210/anat.htm# - The autonomy of a snail.
5. http://www.weichtiere.at/Mollusks/Schnecken/morphologie/schale.html - snail site
6. http://www.cnsm.csulb.edu/programs/nsfs/research/drmason/gastropod/diagram_prosobranchia.html - detailed diagram
7. www.marlin.ac.uk
8. http://meat.tamu.edu/muscontract.html
Scientific papers
9. Grahame, J and Mill, P.J. (1986) – Relative size of the foot of two species of Littorina on the rocky shore in Wales.
10. The columellar muscle of prosobranch gastropods: morphological zonation and its functional implications. Thompson, J.T., Lowe, A.D., and Kier, W.M. Invertebrate Biology. 117(1): 45-56. 1998.
11. Tenacity of attachment in two species of Littorinia, litorria littorea and Littorina Obtusata – Mark s. Davies and Cherys M. Case
Books
12. A students guide to the sea shore – J.d Fish and S Fish
13. Advanced Biology – Michael Kent
14. Biology: Principles and Processes – Michael Roberts, Michael Reiss ans Grace Monger
I'm bet ur glad thats over <Yawn> .
Fair well, sweet dreams <cheers>
The common Periwinkle (Latin name – Littorina Littorea) is part of the prosobranch gastropods family, which also includes Calliostoma euglyptum and Ilyanassa obsolete9. They are found on most coasts of Britain except on extremely exposed shores. They are found mostly on rocks and cliffs but also muddy or sandy areas such as mud flats and estuaries where sea and fresh water meet, due to the periwinkles high tolerance to saline waters of up to 15m.
The maximum length of a periwinkle is around 4 cm, fertilisation is internal and the sexes are separate. For nutrients the Common Periwinkle slides along a surface, such as a rock pool, consuming microorganisms, using the foot at the bottom of the shell for movement. This normally takes the form of regular, continuous gliding. The foot is composed of string muscles, and is connected to the head, which has a mouth and sensory organs (used to gather information and food). The under surface of the foot is known as the sole, which is surrounded by a foot fringe (like a border). The soleslides over a thin layer of mucous secreted by a gland situated in the front part of the foot4. This is one of reasons why dehydration is such an important issue for Common Periwinkle.
One of the greatest threats faced by periwinkles are predators. Its highest defence against this threat is its shell composed of mostly Calcium carbonate in a protein matrix. This shell is composed of three layers:
1. The outer organic periostracum layer
2. The middle calcareous layer
3. The inner calcareous nacreous layer
These three layers provide a quite strong barrier and dissuade predators from bothering to catch them, instead going for easier targets The is shell secreted by a tissue called the mantle and is only connected to the Periwinkles body at one point, where the columellar muscle attaches its self to the end spindle of the shell (as seen below3). If it looses its shell it will most certainly die due to predators and dehydration.
However the greatest problem is dehydration, which the shell’s structure helps to prevent. Dehydration is such a treat because Periwinkles need water for many of their living processes and are constantly using it. For example their movement requires mucus-containing water to allow them to slide along surfaces in order to collect food.
To protect itself the Periwinkle attaches its self to a solid surface (e.g. rocks/cliffs) when the tide withdraws. It does this by retracting from outside and dispensing a type of mucus which dries and hardens in the air, producing an air proof seal to limit evaporation and transpiration rates. The thick skin which covers the back and sides of the Periwinkle’s body also contains large numbers of mucous glands. Mucous released in to the network of furrows between the tubercles (small bumps on the skin) spreads over the whole of the animal's body, so that the evaporation of water from the animal's skin is reduced4. The Common Periwinkle may also attach itself to damp sea weed algae using it’s foot, this is how the periwinkles will attach them selves to the petri dishes using their foot while they are outside of their shells. Both methods also protect against rough wave action and being picked up and crushed against rocks while they are dormant or out feeding.
Below is a Semi-schematic diagram illustrating some of the external anatomical features of the marine prosobranch gastropod Littorina littorea. The animal has been removed from the shell and is viewed from the left hand side6 and has a key below.
http://www.cnsm.csulb.edu/programs/nsfs/research/drmason/gastropod/diagram_prosobranchia.html
The columellar muscle in Periwinkles is a flat muscle, which starts at the coil of the shell and ends at the operculum. The columellar muscle is mostly made of a densely packed three- dimensional muscles and connecting tissue fibres9. The fibre arrangements are not the same through out the muscle; there are three regions, which blend into each other. The columellar muscle at the spindle of the Periwinkle is made up of mostly longitudinal muscle fibres with few fibres running along the columellar or transverse fibres, and no slanting fibres. The middle part of the columellar muscle in the zone before the head consists of longitudinal, fibres running along the columellar, and transverse fibres wrapped by two opposite layers of slanting fibres. The third region of the columellar muscle extends through the foot and includes longitudinal, transverse, and fibres that run along the columellar and out of the shell with a layer of slanting fibres on the back surface. A narrow line of spherical spaces divides the columellar muscle into dorsal and ventral halves in this zone. Each zone performs a different function to the Periwinkle. This dense three-dimensional muscle is what makes the snails hold so strong compared to its relatively small volume unlike animal cylindrical muscles.
Muscles are the only issue in the body, which may contract, this means it may change its length or become tense, they take up 40% to most animals. The main muscle type used in Common Periwinkles is smooth muscle. It is made up of many slender muscle fibres. Every Muscle fibre contains a single cell with a nucleus and cytoplasm about 0.2 mm long, the cytoplasm contains the protein Myofibrils that are responsible for muscle contraction as is the protein Actin. These two proteins together are the basis of, muscle contraction. This happens by thick (Actin) and thin (Myofibrils) filaments sliding between each other, the thick filaments are held together at the M line and the Thick elements are held together at the z line, both sets move as a unit. There are many theories on how muscles contract but the most believed on is the "sliding filament" hypothesis. This happens because thick and thin filaments are in a pattern in the sarcomere. Each thick filament is surrounded by 6 thin filaments. A large protein molecule called Titin connects these thick filaments to the Z disk and maintains the order of thick and thin filaments. Titin is also responsible for the muscle's resistance to stretching after a certain threshold.
For the columellar muscle to contract the following line of events must occurs in order. The events, which happen before the contraction, are started by the central nervous system, either as voluntary activity from the brain or as reflex activity from the spinal cord. A motor neuron in the ventral horn of the spinal cord is activated, and an action potential passes outward in a ventral root of the spinal cord. The axon branches to supply a number of muscle fibres called the motor unit; the action signal is sent to the motor end plate on each fibre. When it reaches the motor end plate, the action causes the release of packets (quanta) of acetylcholine into the synaptic clefts on the surface of the muscle fibre.
Acetylcholine causes the electrical resting signal under the motor end plate to change, and this then initiates an action signal, which passes in both directions along the surface of the muscle fibre. At the end of each transverse tubule onto the muscle fibre surface, the action signal spreads inside the muscle fibre. At each point where a transverse tubule touches part of the sarcoplasmic reticulum, it makes the Sarcoplasmic reticulum release Ca+ ions. The calcium ions result in movement of Troponin and Tropomyosin on their thin filaments, and this enables the myosin molecule to bridge itself, causing contractions.
The contractions then must be stopped; this is done by acetyl cholinesterase, which break down Acetylcholine. So that no more signals may be sent along the muscle. The sarcoplasmic reticulum then stops releasing calcium ions and gathers up the ones it released earlier. With no calcium ions a change in the configuration of Troponin and Tropomyosin then blocks the action of the myosin molecule heads from bridging, and contraction stop. Gravity then helps to pull the muscle back to its original shape.
Biography
Internet sites
1. www.sportesport.it/ shellsGA28.htm
2. http://www.vattenkikaren.gu.se/fakta/arter/mollusca/prosobra/littlitt/littli4e.html
3. http://oceanlink.island.net/oinfo/intertidal/mollusca.html
4. http://www.geocities.com/Heartland/Valley/6210/anat.htm# - The autonomy of a snail.
5. http://www.weichtiere.at/Mollusks/Schnecken/morphologie/schale.html - snail site
6. http://www.cnsm.csulb.edu/programs/nsfs/research/drmason/gastropod/diagram_prosobranchia.html - detailed diagram
7. www.marlin.ac.uk
8. http://meat.tamu.edu/muscontract.html
Scientific papers
9. Grahame, J and Mill, P.J. (1986) – Relative size of the foot of two species of Littorina on the rocky shore in Wales.
10. The columellar muscle of prosobranch gastropods: morphological zonation and its functional implications. Thompson, J.T., Lowe, A.D., and Kier, W.M. Invertebrate Biology. 117(1): 45-56. 1998.
11. Tenacity of attachment in two species of Littorinia, litorria littorea and Littorina Obtusata – Mark s. Davies and Cherys M. Case
Books
12. A students guide to the sea shore – J.d Fish and S Fish
13. Advanced Biology – Michael Kent
14. Biology: Principles and Processes – Michael Roberts, Michael Reiss ans Grace Monger
I'm bet ur glad thats over <Yawn> .
Fair well, sweet dreams <cheers>
