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The diet of the pufferfish includes mostly invertebrates and algae. Large specimens will even crack open and eat clams, mussels, and shellfish with their hard beaks. Poisonous puffers are believed to synthesize their deadly toxin from the bacteria in the animals they eat.
This creature's looks earned it the name ghost shark, but it's actually a fish that falls into the chimaera, or ratfish, group.
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The arapaima (), called a pirarucu in Brazil, is one of the largest fish in South America. This fish was photographed in Manuas, Brazil, in 2007. The Atlantic salmon (Salmo salar), 'the leaper', has been called the king of fish, due primarily to its spectacular ability to clear…
Photo provided by FlickrThis creature's looks earned it the name ghost shark, but it's actually a fish that falls into the chimaera, or ratfish, group.
Photo provided by FlickrAs with many aquatic animals, most fish release their nitrogenous wastes as . Some of the wastes  through the gills. Blood wastes are  by the .
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One reason fish are so diverse is that 70 percent of the planet is covered in water. The animals in this group live in a variety of habitats ranging from coral reefs and kelp forests to rivers, streams, and the open ocean. Another is that fish are very old on the evolutionary scale. According to fossil records, they have been on Earth for more than 500 million years! The total number of living fish species—about 32,000— is greater than the total of all other vertebrate species (amphibians, reptiles, birds, and mammals) combined.Stellate or “starry” sturgeons live in salt water but return to freshwater rivers to breed. These ancient fish are now extinct in the Aegean Sea, and the surviving Black and Caspian Sea populations are being decimated by fishing, much of it illegal. Despite stocking efforts, the IUCN estimates that the number of stellate sturgeons has plunged at least 80 percent in the past 30 to 40 years and will soon reach zero if demand for their celebrated caviar doesn’t ease. Sturgeons, like their relatives the paddlefish, are among the relatively few fish species to employ electroreceptive abilities.One reason fish are so diverse is that 70 percent of the planet is covered in water. The animals in this group live in a variety of habitats ranging from coral reefs and kelp forests to rivers, streams, and the open ocean. Another is that fish are very old on the evolutionary scale. According to fossil records, they have been on Earth for more than 500 million years! The total number of living fish species—about 32,000— is greater than the total of all other vertebrate species (amphibians, reptiles, birds, and mammals) combined.A diver meets a living fossil while swimming with a coelacanth in an Indonesian national park. Famously thought to have gone extinct with the dinosaurs, the species was rediscovered in 1938. Coelacanths boast an electrosensory rostral organ in their snouts—an intriguing prey-seeking adaptation in an animal some think represents an early stage of fish-land animal evolution.The primitive, eel-like Pacific lamprey has a sucker mouth with which it affixes itself to larger fish as a parasite. Adult lampreys live in salt water then migrate upriver to spawn. The presence of an electroreceptive system in these most primitive living vertebrates, which have remained largely unchanged for 360 million years, suggests that the very first vertebrate animals may have had the same ability.The lobetoothed piranha (P. denticulate), which is found primarily in the basin of the Orinoco River and the tributaries of the lower Amazon, and the San Francisco piranha (P. piraya), a species native to the San Francisco River in Brazil, are also dangerous to humans. Most species of piranhas, however, never kill large animals, and piranha attacks on people are rare. Although piranhas are attracted to the smell of blood, most species scavenge more than they kill. Some 12 species called wimple piranhas (genus Catoprion) survive solely on morsels nipped from the fins and scales of other fishes, which then swim free to heal completely.