Osteichtheys Bony Fish

1. OsteichtheysBony Fish

2. Main Characteristics • Endoskeleton hardened by Calcium phosphate • Closed Circulatory system, two chambered Heart • Deuterostomes with bilateral symmetry • Notochord, a longitudinal flexible rod present in all embryos • Dorsal hollow nerve chord • Pharyngeal Pouches allow water that enters mouth to exit at gill pouches • Postanal tail

3. Osteichthyes are divided into three subclasses: • 1 . The subclass Dipnoi (lungfish) is characterized by an upper jaw fused to the braincase, fused teeth, and the presence of an air-breathing organ that opens to the esophagus. A lungfish's caudal fin is continuous with its dorsal and anal fins. Its pelvic and pectoral fins are long and tubular. South American Lungfish Australian Lungfish

4. 2. The subclass Crossopterygii is characterized by cosmoid scales, two dorsal fins, and fleshy paired fins that contain skeletal elements. Coelacanth

5. 3. The subclass Actinopterygii includes all other living bony fishes. Actinopterygians are characterized by rayed fins. Clown Triggerfish Sturgeon

6. Evolution • The modern bony fishes, class Osteichthyes, appeared in the late Silurian or early Devonian, about 395 million years ago. The early forms were freshwater fish,for no fossil remains of modern bony fishes have been found in marine deposits older than Triassic time, about 230 million years ago. The Osteichthyes may have arisen from the acanthodians. A subclass of the Osteichthyes, the ray-finned fishes (subclass Actinopterygii), became and have remained the dominant group of fishes throughout the world. It was not the ray-finned fishes, however, that led to the evolution of the land vertebrates.

7. Chordates Craniates Vertebrates Gnathostomes Osteichthyans Lobe-fins Tetrapods Amniotes Echinodermata(sister group to chordates) Cephalaspidomorphi(lanpreys) Chondrichthyes(sharks, rays, chimaeras) Amphibia(frogs, salamanders) Cephalochordata(lamcelets) Actinopterygii(ray-finned fishes) Reptilia(turtles, snakes,crocodiles, birds) Urochordata(tunicates) Actinistia(coelacanths) Dipnoi(lungfishes) Myxini(hagfishes) Mammalia(mammals) Milk Amniotic egg Legs Lobed fins Lungs or lung derivatives Jaws, mineralized skeleton Vertebral column Head Brain Notochord Ancestral deuterostome Ancestry

8. Unique Characteristics • These fish have a skeleton composed of bone instead of cartilage. • Paired fins & one pair of gill openings • Jaws & paired nostrils. • Flattened bony scales covering their skin Myripristis Jacobus

9. The swim bladder is a flexible-walled, gas-filled sac located in the dorsal portion of body cavity. This organ controls the fish's buoyancy and in some species is important for hearing. • The lateral line system is sensitive to differences in water pressure. These differences may be due to changes in depth or to the currentlike waves caused by approaching objects.

10. Habitat These bony fish have many different types of water habitats including: • Freshwater lakes & ponds • Shoreline shallows • Deep water • Freshwater rivers and streams • Riverbanks & estuaries • Wetlands • Open ocean • Intertidal zone

11. Miscellaneous • Most species reproduce by external fertilization after the female sheds a large number of eggs. Although, internal fertilization and birthing occur in other species. • Small fish like to roam open areas of a lake and feed on zooplankton. Larger fish often follow these small fish and feed on them • Fish tend to feed on either vegetation or other fish or smaller marine life

12. “People save what they love.” -Jacques Cousteau

13. Compare Contrast • Compare and Contrast the three subclasses of bony fish • Dipnoi, • Crossopterygii, • Actinopterygii.