Jawless Entelognathus primordialis is the most ancient fish.
The Lamprey is an eel-like shaped, jawless fish of the order Petromyzontiformes.
Blobfish, like other fish, possess a centralized nervous system that includes a brain and spinal cord, along with a peripheral nervous system. Their nervous system is adapted to their deep-sea environment, where they experience high pressure. Blobfish are not known for complex behaviors; their nervous system primarily facilitates basic functions such as movement and sensory processing. Overall, their nervous system reflects their unique habitat and lifestyle as a deep-sea species.
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Bony fishHag fishLamprey(both of these are known as the jawless fish)Sharks and rays(both of these are known as cartilaginous fish)Lob-finned fishThis is a very simplified classification of something that is very complex. To see the full tree, try WikiSpieces.
They were jawless fish that lived during the Paleozoic era Stunningly some of our oldest ancestors came from ostracoderms!
Agnathans are the jawless fish. They are usually fairly small (a few centimeters in length.) They consist of lancelets and tunicates. They have a notochord which is like a backbone, but it is more flexible than bone. Tunicates are enveloped by a tough tunic around their bodies. Other than that, they have no other bones.
They don't have a central nervous system. Just 2 ganglia.
intrinsic eye muscles are controlled by the autonomic nervous system
central
Both jawless fish and cartilaginous fish have skeletons composed of cartilage and distinct brains. Also, some cartilaginous fish don't have scales, and all jawless fish don't have scales. Cartilaginous fish, however, have jaws, paired appendages, and a kind of vertebrae. Jawless fish do not have jaws, paired appendages, and often are without vertebrae.
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