Fish are the gill-bearing aquatic craniate animals that lack limbs with digits. They form a sister group to the tunicates, together forming the olfactores. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Tetrapods emerged within lobe-finned fishes, so cladistically they are fish as well. However, traditionally fish are rendered paraphyletic by excluding the tetrapods (i.e., the amphibians, reptiles, birds and mammals which all descended from within the same ancestry). Because in this manner the term "fish" is defined negatively as a paraphyletic group, it is not considered a formal taxonomic grouping in systematic biology. The traditional term pisces (also ichthyes) is considered a typological, but not a phylogenetic classification.
The earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessed notochords which allowed them to be more agile than their invertebrate counterparts. Fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. Many fish of the Paleozoic developed external armor that protected them from predators. The first fish with jaws appeared in the Silurian period, after which many (such as sharks) became formidable marine predators rather than just the prey of arthropods.
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Barracuda (Finding Nemo) -
Brooke -
Coral -
Marlin -
Dave (SpongeBob SquarePants) -
William -
Pufferfish -
Giuseppe
All items (177)
- Finn (Goldfish)
- Fish (Blue's Clues)
- Fish (CoCoMelon)
- Fish (Dave and Ava)
- Fish (Elmo's World)
- Fish (FunBrain)
- Fish (Kemy)
- Fish (Kidsongs)
- Fish (KiiYii)
- Fish (Loo Loo Kids)
- Fish (PBS KIDS)
- Fish (Starfall)
- Fish (Super Simple Songs)
- Fish (Super Simple Songs: Yes, I Can!)
- Fish (Super Why)
- Fish (The Cat in the Hat)
- Fish (Toonbo)
- Fish (Wide Open Space)
- Fish (WordWorld)
- Fishes (Elmo's World)
- Five Fish
- Flounder
- Frances Piscine
- Frank (SpongeBob SquarePants)
- Frankie
- Fred Fish (Maple Leaf Learning)
- Fugu
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- Seaking
- Seven Diamond Fish
- Seven Goldfish
- Shark (AppuSeries)
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- Shark (Bee at the Beach)
- Shark (HooplaKidz)
- Shark (Kemy Expedition)
- Shark (Peculiar Penguins)
- Shark (Sea Scouts)
- Shark (Super Simple Songs)
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- Sheldon the Seahorse
- Shellsea
- Splash
- Starfish (Barney & Friends)
- Starz
- Steve (SpongeBob SquarePants)
- Super, Dee and Duper
- Swellbellies
- Swimmington
- Sykes