The Integumentry
System of Fishes
Integument of vertebrate is skin and it is the largest
organ. It grows as animal grows.
The skin of
jawless fishes
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Thick skin is present in the lampreys and
hagfishes.
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Protective cuticle is secreted by epidermal
glandular cells.
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Slime eels are the name given to hag fishes
because large amount of mucus slime is present on the whole body that is
secreted by slime glands and protects from damage and external parasites.
The Skin of
Cartilaginous Fishes
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Multilayered skin is present in these fishes.
Mucus and sensory cells are also present.
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Denticles (like vertebrates teeth) which are
dermal bone in the form of placoid scales are present in dermis. Denticles also
have nerves and blood vessels. Denticles are continuously wear down and lost.
They do not grow once they reach maturity and they project out of the body and
give these fishes a sand paper appearance.
The Skin of
Bony Fishes
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Dermal bone in the form of scales is also
present in the bony fishes. Unlike cartilaginous fishes, scales are not shed
thus help in the age determining of fishes because these scales grow at the
margins and form growth lines.
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The skin of these fishes help in the gaseous
exchange as it is permeable.
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To facilitate the respiration, extensive
capillary bed is present in the dermis.
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Mucus produced in mucus gland that is present in
epidermis helps in preventing fungal and bacterial infections.
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Poisonous or irritating alkaloids are secreted
by granular gland in some species.
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Photophores are present in some bony fishes that
live in deep aquatic water and help in reorganization and act as warning
signals.
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