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Types of ScalesTypes of Scales
in Fishesin Fishes
ScaleScale
• A A scalescale is a small rigid plate thatis a small rigid plate that
grows out of an grows out of an animal'...
•The study of scales isThe study of scales is
called called SquamatologySquamatology ..
Development &Development &
LocationLocation
• Produced in the mesoderm.Produced in the mesoderm.
• Located between the epi...
Functions ofFunctions of
ScalesScales
• Provide external protection to its body as scalesProvide external protection to it...
Types of ScalesTypes of Scales
• There are four different types of fishThere are four different types of fish
scales.scale...
• The structure and configuration of scalesThe structure and configuration of scales
can be used to determine the species ...
1.Placoid Scales1.Placoid Scales
• Also called denticles, are similar in structureAlso called denticles, are similar in structure
to teeth.to teeth.
• Foun...
• Placoids have a sharp ridge down thePlacoids have a sharp ridge down the
center of the scale made ofcenter of the scale ...
2. Cosmoid Scales2. Cosmoid Scales
• Very rare scale type, but no doubt common inVery rare scale type, but no doubt common in
extinct speciesextinct species ...
• Inner layer of theInner layer of the
scale is madescale is made
of lamellar bone.of lamellar bone.
• On top of this lies...
3. Ganoid Scales3. Ganoid Scales
• These can be foundThese can be found
on gars, bichirs andon gars, bichirs and
reed fishes.reed fishes.
• Rare among mode...
• They have a bony base layer similar to that ofThey have a bony base layer similar to that of
cosmoid scales. Indeed, gan...
• They act like armor to form a nearlyThey act like armor to form a nearly
impenetrable barrier to predators.impenetrable ...
4. Leptoid scales4. Leptoid scales
• Found on higher-order bony fish.Found on higher-order bony fish.
• As they grow they ...
Cycloid ScalesCycloid Scales
• Cycloid and ctenoidCycloid and ctenoid
scales have differentscales have different
shapes but the sameshapes but the same...
• These have two basic parts;These have two basic parts;
1.1.The inner solid structure madeThe inner solid structure made
...
• Scales are notScales are not
shed as the fishshed as the fish
ages, but growages, but grow
with the animal.with the anim...
• Herring and other groups of bony fishHerring and other groups of bony fish
have large cycloid scales that fall offhave l...
Ctenoid scalesCtenoid scales
• They have a toothedThey have a toothed
outer edge (exposedouter edge (exposed
part), spiny or havepart), spiny or have
c...
  Scute ScaleScute Scale
• Another less common, type of scale isAnother less common, type of scale is
the the scutescute, ...
• Some fish, such as pinecone fish, areSome fish, such as pinecone fish, are
completely or partially covered incompletely ...
Scaleless FishScaleless Fish
• Some groups of fish lack scalesSome groups of fish lack scales
completely, including gobies...
ReferencesReferences
• www.wikipedia.orgwww.wikipedia.org
• www.australianmuseum.netwww.australianmuseum.net
• www.newton....
Types of Scales in Fishes
Types of Scales in Fishes
Types of Scales in Fishes
Types of Scales in Fishes
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Types of Scales in Fishes

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Types of Scales in Fishes

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Types of Scales in Fishes

  1. 1. Types of ScalesTypes of Scales in Fishesin Fishes
  2. 2. ScaleScale • A A scalescale is a small rigid plate thatis a small rigid plate that grows out of an grows out of an animal's skin to's skin to provide protection.provide protection. • Generally classified as part of anGenerally classified as part of an organism's integumentary system.organism's integumentary system.
  3. 3. •The study of scales isThe study of scales is called called SquamatologySquamatology ..
  4. 4. Development &Development & LocationLocation • Produced in the mesoderm.Produced in the mesoderm. • Located between the epidermis and theLocated between the epidermis and the underlying tissues.underlying tissues. • Genes responsible for the development ofGenes responsible for the development of scales in fish are same that result in hairscales in fish are same that result in hair and tooth development in mammals.and tooth development in mammals. • They usually grow on a fish inThey usually grow on a fish in overlapping plates, with the free endoverlapping plates, with the free end of the scale pointed towards the tail.of the scale pointed towards the tail.
  5. 5. Functions ofFunctions of ScalesScales • Provide external protection to its body as scalesProvide external protection to its body as scales are tough & slippery.are tough & slippery. • Help to protect a fish from scrapes, parasitesHelp to protect a fish from scrapes, parasites and other external injuries.and other external injuries. • Because they are all attached at only oneBecause they are all attached at only one point, they provide flexibility so that thepoint, they provide flexibility so that the scales can slide over each other as thescales can slide over each other as the fish’s body bends while swimming.fish’s body bends while swimming.
  6. 6. Types of ScalesTypes of Scales • There are four different types of fishThere are four different types of fish scales.scales. 1.1. Cosmoid scalesCosmoid scales 2.2. Ganoid scalesGanoid scales 3.3. Placoid scalesPlacoid scales 4.4. Leptoid scalesLeptoid scales • Cycloid scalesCycloid scales • Ctenoid scalesCtenoid scales
  7. 7. • The structure and configuration of scalesThe structure and configuration of scales can be used to determine the species fromcan be used to determine the species from which they came.which they came. • The type of scale will affect the behavior ofThe type of scale will affect the behavior of a fish:a fish: • Larger, heavier scales providing moreLarger, heavier scales providing more protection but restricting movement .protection but restricting movement . • Smaller, lighter scales offering moreSmaller, lighter scales offering more freedom of movement but less protection.freedom of movement but less protection.
  8. 8. 1.Placoid Scales1.Placoid Scales
  9. 9. • Also called denticles, are similar in structureAlso called denticles, are similar in structure to teeth.to teeth. • Found on sharks, skates and rays.Found on sharks, skates and rays. • Formed of a rectangular base plate that isFormed of a rectangular base plate that is embedded within the skin of the fish.embedded within the skin of the fish. • The interior of the scale is a pulp that receivesThe interior of the scale is a pulp that receives blood from the fish's vascular system, while theblood from the fish's vascular system, while the outside is made of an enamel-like substanceoutside is made of an enamel-like substance called vitrodentine.called vitrodentine.
  10. 10. • Placoids have a sharp ridge down thePlacoids have a sharp ridge down the center of the scale made ofcenter of the scale made of vitrodentinevitrodentine.. • The enamel ridge is calledThe enamel ridge is called an an ectodermal capectodermal cap , and this is important, and this is important because without this enamel cap thebecause without this enamel cap the sharks could not feed.sharks could not feed. • Placoids do not grow with the fish. As aPlacoids do not grow with the fish. As a shark gets larger it grows new scales to fillshark gets larger it grows new scales to fill in the gaps between the scales. in the gaps between the scales. 
  11. 11. 2. Cosmoid Scales2. Cosmoid Scales
  12. 12. • Very rare scale type, but no doubt common inVery rare scale type, but no doubt common in extinct speciesextinct species CrossopterygiansCrossopterygians , is the, is the cosmoid scale. cosmoid scale.  • Limited today to the primitive lobefinsLimited today to the primitive lobefins and lungfish.and lungfish. • Cosmoid scales evolved from placoid scalesCosmoid scales evolved from placoid scales fusing together.fusing together. • This is because cosmoid scales have two baseThis is because cosmoid scales have two base plates and similar external spines composed ofplates and similar external spines composed of vitrodentine.vitrodentine.
  13. 13. • Inner layer of theInner layer of the scale is madescale is made of lamellar bone.of lamellar bone. • On top of this lies aOn top of this lies a layer of spongylayer of spongy or vascular bone andor vascular bone and then a layerthen a layer of dentine-likeof dentine-like materialmaterial called cosmine.called cosmine. • These scales growThese scales grow along with the fish.along with the fish.
  14. 14. 3. Ganoid Scales3. Ganoid Scales
  15. 15. • These can be foundThese can be found on gars, bichirs andon gars, bichirs and reed fishes.reed fishes. • Rare among modernRare among modern fish.fish. • They are flat, basal-They are flat, basal- looking scales.looking scales. • What’s unusual aboutWhat’s unusual about these scales is thatthese scales is that they do not overlapthey do not overlap but instead fit togetherbut instead fit together like pieces of a jigsawlike pieces of a jigsaw puzzle.puzzle.
  16. 16. • They have a bony base layer similar to that ofThey have a bony base layer similar to that of cosmoid scales. Indeed, ganoid scales arecosmoid scales. Indeed, ganoid scales are modified cosmoid scales.modified cosmoid scales. • However, they differ in that their outer layer isHowever, they differ in that their outer layer is made of an inorganic bone salt called ganoinemade of an inorganic bone salt called ganoine and that they are diamond-shaped andand that they are diamond-shaped and interconnected.interconnected. • Between ganoid scales are peg-and-socketBetween ganoid scales are peg-and-socket joints that articulate.joints that articulate.
  17. 17. • They act like armor to form a nearlyThey act like armor to form a nearly impenetrable barrier to predators.impenetrable barrier to predators. • They also grow with the fish, not onlyThey also grow with the fish, not only in length, but in width and thicknessin length, but in width and thickness as well.as well.
  18. 18. 4. Leptoid scales4. Leptoid scales • Found on higher-order bony fish.Found on higher-order bony fish. • As they grow they add concentric layers. As they grow they add concentric layers.  • The two types are often groupedThe two types are often grouped together simply astogether simply as "bony-ridged""bony-ridged" scales.scales. • They come in two forms:They come in two forms: 1.1. Cycloid ScalesCycloid Scales 2.2. Ctenoid ScalesCtenoid Scales
  19. 19. Cycloid ScalesCycloid Scales
  20. 20. • Cycloid and ctenoidCycloid and ctenoid scales have differentscales have different shapes but the sameshapes but the same composition andcomposition and positioning.positioning. • The vast majority ofThe vast majority of bony fish have cycloid,bony fish have cycloid, or round scales.or round scales. • These have a smoothThese have a smooth outer edge and are mostouter edge and are most common on fish with softcommon on fish with soft fin rays suchfin rays such as salmon and carp.as salmon and carp.
  21. 21. • These have two basic parts;These have two basic parts; 1.1.The inner solid structure madeThe inner solid structure made out of bone.out of bone. 2.2.An outer collagen layer.An outer collagen layer.
  22. 22. • Scales are notScales are not shed as the fishshed as the fish ages, but growages, but grow with the animal.with the animal. • The result of this,The result of this, is that a fish canis that a fish can be aged bybe aged by counting thecounting the growth rings.growth rings.
  23. 23. • Herring and other groups of bony fishHerring and other groups of bony fish have large cycloid scales that fall offhave large cycloid scales that fall off very easily. Skin structures that arevery easily. Skin structures that are shed easily are known as shed easily are known as deciduousdeciduous scalesscales..
  24. 24. Ctenoid scalesCtenoid scales
  25. 25. • They have a toothedThey have a toothed outer edge (exposedouter edge (exposed part), spiny or havepart), spiny or have comb-like ridges.comb-like ridges. • Usually found on fishUsually found on fish with spiny fin rays,with spiny fin rays, suchsuch as as bassbass and  and crappiecrappie.. • These have tiny teeth-These have tiny teeth- like protrusions calledlike protrusions called ctenii, giving them actenii, giving them a rougher texture.rougher texture.
  26. 26.   Scute ScaleScute Scale • Another less common, type of scale isAnother less common, type of scale is the the scutescute, which is:, which is: • An external shield-like bony plate, orAn external shield-like bony plate, or • A modified, thickened scale that oftenA modified, thickened scale that often is keeled or spiny.is keeled or spiny.
  27. 27. • Some fish, such as pinecone fish, areSome fish, such as pinecone fish, are completely or partially covered incompletely or partially covered in scutes.scutes.
  28. 28. Scaleless FishScaleless Fish • Some groups of fish lack scalesSome groups of fish lack scales completely, including gobies and toadfish.completely, including gobies and toadfish. • Instead, these fish are covered in aInstead, these fish are covered in a coating of slime which will protect the fishcoating of slime which will protect the fish from injury and ectoparasites.from injury and ectoparasites. • The slime layer may serve the addedThe slime layer may serve the added function of making them especially hardfunction of making them especially hard for a predator to grab hold of.for a predator to grab hold of.
  29. 29. ReferencesReferences • www.wikipedia.orgwww.wikipedia.org • www.australianmuseum.netwww.australianmuseum.net • www.newton.depwww.newton.dep • www.ehow.comwww.ehow.com • www.earthlife.netwww.earthlife.net • web.mac.comweb.mac.com

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