message2=CHIMERAS - Cartilaginous fishes related to sharks and rays with single gill cover with one opening covering 4 gills. Living species have different reproductive structures than sharks and rays. Females have no cloaca and males have claspers on their heads. General characteristic of lineage not well known from fossils. &message3=PLACODERMI - Placodermi - Extinct jawed armored fish that were mostly small, although some grew to be very large, up to 30 feet long. Armor made up of true bone. Uncertain whethr they had teeth made only of special dentine rather than typical tooth material. Most were bottom-living marine fishes. &message4=STURGEON - 25 species of very large fishes that move between fresh and salt water to feed on the bottom. They have fin rays, barbels, a cartilaginous skeleton, no scales excect a few that have been modified into bony ridges on the back and sides, and many eggs that are sometimes harvested for caviar. &message5=GARS - large mostly freshwater fish confined to North America. They are lie-in-wait predators. Needle-like teeth, heavy armor of hard diamond-shaped scales. Air bladder that serves as a lung in warm stagnant waters. &message6=BOWFIN - Single freshwater species in eastern North America. &message7=TELEOSTS - Includes most modern fishes. They have symmetrical tails for powerful forward thrust, light weight bones, highly manueverable fins, jaws adjusted for suction feeding as well as biting, gas bladders that allow vertical motion, and thin strong scales. Great variety of shapes. &message8=COELACANTH - Two living species of marine fishes from off southern Africa and Indonesia. &message9=LUNGFISH - Six living species of freshwater fishes that live on the southern continents of Africa, South America and Australia. &actino=ACTINOPTERYGII - Ray-finned fishes. &sarco=SARCOPTERYGII - Lobe-finned fishes and the tetrapods. &gnatho=GNATHOSTOMATA - Fishes with jaws that were derived from modified gill arches. Usually with paired fins, &placodermi=PLACODERMI - Extinct jawed armored fish that were mostly small, although some grew to be very large, up to 30 feet long. Armor made up of true bone. Uncertain whethr they had teeth made only of special dentine rather than typical tooth material. Most were bottom-living marine fishes. &chond=CHONDRICHTHYES - Cartilaginous fishes that include chimaeras and elasmobranchs. Elasmobranchs include sharks and rays. &message10=ACANTHODIANS - Small cartilaginous fishes with large eyes and mouths more towards front of head than sharks. &message14=OSTRACODERMS - Includes several extinct groups of jawless armored fishes - Osteostracomorphi, Thelodonti, Anaspida and Pteraspidomorhi. All had bony head coverings made of either dermal bone or true bone. Most lacked paired fins. &message15=CONODANTA - Extinct, minnow-sized, eel-shaped, jawless and soft-bodied craniates (controversial). Until recently, they were only known from fossils of their complex tooth structures. Recent fossil finds show the conodont had simpler myomeres, the chevron-shaped muscle blocks found in all other craniates. &message16=LAMPREYS - Jawless, soft-bodied, eel-shaped and sometimes parasisitc vertebrate with no bones or paired fins. Has rasping teeth that allow parasitic species to attach to fish to feed on blood. Undergoes metamorphism, parsitic and non-parasitic species and life stages, lays hundreds of eggs and dies after spawning. Visible pores along the side connect to gills. &message17=HAGFISH - Jawless, soft-bodied, eel-shaped scavengers with no fins or vertebrae. Only craniate with body fluids that are isosmotic with seawater. Hagfishes have teeth on tongue and barbels. Excretes slimy mucous from pores along the lower sides of the body. Few large yolky eggs. &message18=CRANIATES - Include all animals that are descendants of the first animal that had a cranium including skull, brain, and sensory organs. The first craniates are the first fishes. Craniates are vertebrates exept for hagfishes. All land vertebrates are descendants of a branch of fishes - the lobe-fins. &message19=AGNATHANS - Jawless fishes in constrast with Gnathostomes. Includes hagfishes and lampreys, and extinct groups - conodonts and ostracoderms. Most lack paired fins and true bones. Some soft-bodied, others externally armored. &message20=VERTEBRATES - Animals with backbones that have nerves running on the back side, gastrointestinal tract on the other and a tail section beyond the anus. Bilateral symmetry with paired appendages. Fishes have flaky bundles of muscle attached to vertebrae. &message21=LOBE-FINNED FISHES - Fishes with fins attached to the main body, to the pelvic and pectoral skeletal frame, by single bones or stalks from which the rays radiate. The Sarcopterygians are the lobe-finned fishes. &message22=RAY-FINNED FISHES - Fishes with fins attached to the main body by bony fin rays that radiate outward from the point of connection, rather than at the end of an intervening stalk like the lobe fins. The actinopterygians are the ray-finned fishes. &message23=ARMORED FISHES - Fishes that had external bony armor that provided protection at the expense of maneuverability. Includes the jawless ostracoderms and the jawed placoderms that both went extinct before the end of the Devonian. Most were probably bottom dwellers based on shape, both marine and nonmarine. &placohigh=PLACODERMS - Jawed armored fishes that were mostly small, but some grew to be very large, up to 30 feet long. &tetrahigh=TETRAPODS - Animals with four-limbs that mostly live on land. All amphibians, reptiles, birds and mammals are descendants of a fish that was a lobe-fin. &cartilaginous=CARTILAGINOUS FISHES - have skeletons made of cartilage rather than bone. Includes sharks, rays, chimeras and extinct acanthodians. Fresh and marine species with unique way of using nitrogenous body wastes to raise osmotic pressure of body fluids in marine species. Internal fertilization, few young and slow reproduction. Fossils rare because cartilage doesn't preserve well, however teeth are common. &gnatho=GNATHOSTOMES - Fishes with jaws. Includes fishes with external armoring - placoderms, cartilaginous skeletons - acanthodians and chondrichtyans, and all other living classes of fishes except for hagfish and lampreys. &ostraco=OSTRACODERMS - Jawless armored fishes that were mostly less than a foot long,mostly without paired fins. &placohigh=BONY FISHES - Include fishes with skeletons made of bone instead of cartilage. Includes the majority of living fishes. &elasmo=ELASMOBRANCHS - Cartilaginous fishes that include both sharks and rays. Living species have 5 to 7 gill openings on each side, male does not have clasper. Dermal denticles, rapid tooth replacement common.