![]() ![]() The superclass Tetrapoda of the four-listed animals is considered to be a group within Sarcopterygii and includes amphibians, reptiles, birds, and mammals. For example, hagfish don’t have scales and aren’t true vertebrates (or are considered primitive vertebrates) mudskippers are amphibious fish that can live outside water lungfish use lungs instead of gills to breathe lampreys lack paired fins, and tuna are warm-blooded.Īlso, not all fish groups come from fish lineages. There are several exceptions to the common definition of a fish. Exceptions Hagfish are the only animals that have a skull but no vertebral column. Although interesting, it remains unclear if there was ever an advantage of a hinged jaw.įurthermore, fish may have evolved from a creature similar to a coral sea squirt whose larva resembled primitive fish in very important ways. The diversity of these jawed creatures may prove the evolutionary advantages of a jawed mouth. The first jaws were found in fossils and they lacked any teeth. However, an extant clade, the lampreys may have pre-dated the ancient pre-jawed fish. These jawless fish lineages are mostly extinct now. Additionally, the earliest fish lineages were the Agnatha or the jawless fish.Įarly fish from fossil records are represented by a group of small armored and jawless fish. The earliest chordates formed skulls and spinal columns, which helped to evolve craniates and vertebrates. Fish began to evolve during the Cambrian explosion approximately 530 million years ago. Evolution and Origins Oilfish contain high levels of wax esters, which are indigestible to humans.įish have been evolving and changing for a very, very long time. For example, pet fish mostly eat freeze-dried and frozen foods including bloodworms, brine shrimp, krill, and plankton. It also helps fish find the different nutrition they need in a variety of foods.Īdditionally, pet fish may have a bit of a different diet than fish you find in the wild. It offers a wider range of food options for aquatic animals. This means that they can eat both plants and meat. What do fish eat? Most species of fish fall into the omnivore category. Variations exist but they all provide motion, maneuverability, and stability.įor a list of incredible facts about fish, make sure to read ‘ 10 Incredible Fish Facts.’ Diet Fish eat crustaceans, plants, shrimp, and worms.
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