Fish are classified into the following major groups: Conodonta Hyperoartia Petromyzontidae (lampreys) Pteraspidomorphi (early jawless fish) Galeaspida Pituriaspida Osteostraci Gnathostomata (jawed vertebrates) Placodermi Chondrichthyes (cartilaginous fish) Acanthodii Osteichthyes (bony fish) Actinopterygii Taxonomically, fish are a paraphyletic group: that is, any clade containing all fish also contains the tetrapods, which are not fish. There are over 25,000 species of fish, making them the most diverse group of vertebrates. Some species of fish in the world A fish is a poikilothermic (cold-blooded) water-dwelling vertebrate with gills. However, hyper-saline lakes like the Great Salt Lake do not support fishes.
// Fish ecology Fish can be found in almost all large bodies of water in salt, brackish or fresh water, at depths from just below the surface to several thousand meters. Endothermy, though metabolically costly, is thought to provide advantages such as increased contractile force of muscles, higher rates of digestion. See also gigantothermy. The degree of endothermy varies from the billfish, which warm only their eyes and brain, to bluefin tuna and porbeagle sharks who maintain body temperatures elevated in excess of 20 °C above ambient water temperatures. All sharks in the family Lamnidae – shortfin mako, long fin mako, white, porbeagle, and salmon shark – are known to have the capacity for endothermy, and evidence suggests the trait exists in family Alopiidae (thresher sharks).
Endothermic teleosts (bony fishes) are all in the suborder Scombroidei and include the billfishes, tunas, and one species of "primitive" mackerel (Gasterochisma melampus). Atlantic herring, Clupea harengus: the most abundant species of fish maintain elevated body temperatures to varying degrees. Most birds are Find sites about companion and working dog breeds as well as commercial services and productsPurrfect is a fanlisting for cats and kittens for adoption; abused cats, kittens, For other uses, see Fish (disambiguation). Birds feed on nectar, plants, seeds, insects, rodents, fish, carrion, or other birds. There are over 25,000 species of fish, making them the most diverse class of terrestrial vertebrates.
Atlantic herring, Clupea harengus: the most abundant species of fish in the world A fish is a poikilothermic (cold-blooded) water-dwelling vertebrate with gills. For other uses, see Fish (disambiguation).
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River Cities Pets
Offers information about puppy mills and pet stores. Lists shelters in Ohio, Kentucky, and West Virginia.
FEMA for Kids -- Pets and Disaster
Teaches young owners how to care for their pets when a disaster such as a tornado, flood, or hurricane forces evacuation.
Power Pets
A virtual pet community.
Passports for Pets
Organisation focused on reforming the UK rabies quarantine laws for dogs and cats entering the country.
ideas4pets
Online pet store supplying dog cages, carriers and hutches. Order online.