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Hello everyone, in this question we have been asked to discuss the evolutionary changes and adaptations that occurred in the fishes.
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So, start with jawless fish i .e.
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Hagfish and end with lungfish.
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So, basically the jawless fish i .e.
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The hagfish and relatives myxini, these are the marine organism and have a head that includes the skull, brain, eyes and a sensory organs.
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And after the evolution of these jaw fishes or these gnathic fishes, these are the aquatic gnathosomes, e .g.
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The chondrichthyes that includes the shark, rays etc.
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They have a cartilaginous skeleton i .e.
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Derived trait formed by the reduction of an ancestral mineralized skeleton.
01:04
Then there was the evolution of ray finned fishes that are the actinoptergi.
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These are also the gnathosome and they here have the bony skeleton and manuable fins supported by the rays.
01:23
Then there was actinistia, this is the ancient lineage of aquatic lobe fins that are still surviving in the indian ocean.
01:34
And then there came the lungfishes which are adaptively evolved against the various environment...