Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Zoology Chapter 18 The Fishes Introduction • 70% covered in water • living tissue mostly water • adaptive radiation – formation of new forms from a ancestral species usually in response to new habitats • craniata – skull that surrounds the brain, olfactory organs, eyes and inner ear • 1st found in a lancelet like animal 530 million years ago • some found with teeth Ostracoderms • – bony armor group of fish, inactive filter feeders (extinct) (armor as only defense) – no jaw or paired appendages • Agnatha – no longer exists – used to differentiate between absence of jaw – except lampreys – more in common with cartilaginous fish and bony fish than the hagfish – 41% of all fish species live in freshwater (.0093% by volume on earth’s surface) • The earliest known vertebrates with bone were a diverse group of jawless fish known as ostracoderms. These were armored animals with internal skeletons of cartilage. All other vertebrates evolved from them. The three classes of ostracoderms appeared in the early Silurian and were quite successful well into the Devonian. They had a lateral line system, an inner ear with two semicircular canals, and bones in their external armor. It has been suggested that the armor provided protection from large predatory arthropods like the one in this illustration. Today the only surviving agnathans are the lamprey and hagfish. Survey of fish • Subphylum Hyperotreti – Hagfish – Class myxini • • • • • • • • Lack vertebrae – notochord as support structure 4 pairs of sensory tentacles surrounding their mouths slime glands – produce slime cold water marine habitats most primitive group of craniates live buried in the sand and mud feed on soft bodied invertebrates, dead decaying fish will find a fish enter through it’s mouth and eat leaving a sack of skin and bones • eat hook, swallow all way to anus, cause fisherman to cut line • skin is sold as eel skin Jawless Fish • Hagfish Hagfish a. famous for the mass amounts of slime almost instantly secreted as a defense mechanism. • The internal anatomy of a hagfish includes a notochord that persists into adulthood. A single individual has both ovaries and testes, but only one is functional at any time. The eggs are large and no larval stage has been found, although little is known of reproduction in these animals. They produce copious amounts of slime and can tie themselves into knots to escape predators or obtain leverage while feeding. Subphylum Vertebrata – Ostracoderms, lampreys and gnathostome fishes • Class Cephalaspidomorphi – lampreys – Adults prey on other fish – Larvae are filter feeders – sucker like mouth – sensory sensor lips – use tongue to rasp away scales – anticoagulant and feed on blood – some not predatory – reproduce then die shortly after, will travel miles to spawn – male and female wrap around each other for mating – external fertilization Jawless fish! Lamprey Evolution of Jaws A major advance occurred with the evolution of jaws from anterior gill supports Gnathostomata • jaws of vertebra developed from the most anterior pair of pharyngeal arches – skeletal supports for the pharyngeal slits • gill ventilation and food capture • paired appendages – allow for stability • 2 classes – – – – chondrichthyes – cartilaginous fish osteichthyes – bony most carnivores, or scanvengers placoid scales – allows for reduction of friction within the water, dried shark skin used for sand paper Placoderms (Class Placodermi) are among the earliest known gnathostomes or jawed vertebrates. These armored fish were first found in the Silurian Period and flourished during the Devonian. They were diverse in size and feeding habits. Some reached 10 m in length and were active predators. Others had the flattened form of bottom dwellers. They are not believed to be ancestral to any living vertebrates and were all extinct by the Carboniferous. • The Class Acanthodii, the other group of early gnathostomes, first appeared in the Silurian and persisted until the Permian. In this group the external bony armor was reduced to small plates on the head and scales on the rest of the body. Acanthodians were characterized by numerous spines, at least some of which supported fins, along the top and sides of the body. Most were small, streamlined fish with large eyes. Their relationship to other fish is uncertain; they have been placed with both Chondrichthyes and Osteichthyes. Chondrichthyes – sharks, skates, rays, ratfish • SPOTTED RATFISH - Hydrolagus colliei SPOTTED RATFISH THORNBACK SKATE - Raja clavata Manta Rays Differences between Skates and Rays?? • Reproduction – Rays are viviparous (bearing live young) – Skates are oviparous (laying eggs) Placoid Scales Placoid Scales • cartilaginous skeleton • no swimbladder to regulate bouancy to compensate has 1/3 of weight is liver and oil which gives it bouancy • sharks teeth are modified placoid scales, outer wear out new teeth move in • in young sharks teeth replacement is within 7 to 8 days • types of teeth depend upon what they eat • Venice Florida - Shark and Sharks' Teeth Information sand tiger shark teeth mainly grey shark teeth cowshark teeth • Cow sharks are a primitive type of shark. Whenever a sevengill shark is caught at a pier it is usually the topic of conversation. They are fairly uncommon at piers and are about the largest shark most pier anglers will encounter. A 7-footlong sevengill shark, estimated to weigh 180-185 pounds, was landed at the Cayucos Pier in November of 1998.. Cow Shark Cow sharks (Hexanchidae) are a family of sharks characterized by extra pairs of gill slits. There are probably only two seven-gilled genera • Some of the larger species of sharks are shown here. The whale shark may reach 12 m in length and is the world’s largest fish. It is a filter feeder, using its gills to strain plankton. Marine sharks have body fluids at the same concentration as seawater because they allow urea, a nitrogenous waste product, to accumulate rather than excrete it immediately. • size less than 1 m to greater than 10 meters • largest sharks are filter feeders • most feared great white extinct lengths 15 m 25 feet. The Great White Shark ovoviviparous (some do lay eggs) gill slits, no operculum Female shark reproduction Male Shark Reproduction Male • anal fin - the fin on the • first dorsal fin - the fin lower side of the body on the upper side of the near the tail (not on all body nearest the head sharks) • gills - fleshy organs that • caudal fin - the tail fin are used for breathing they are located on the • eye - sight organs side of the head located on the head • mouth - the part of the • fin spine - a protective body which the fish uses spine located at the base to catch food - it is of the first dorsal fin (not located at the front of the all sharks have fin body spines) • nostril - paired slits on the underside of the snout. Water continually flows through the nostrils, giving the shark olfactory (sense of smell) information. Unlike humans, shark nostrils have nothing to do with breathing - they are not even connected to the mouth. • pectoral fin - each of the paired fins on either side of the body, near the head • pelvic fin - each of the small, paired fins on the lower rear side of the body • second dorsal fin - the fin on the upper side of the body nearest the tail • snout - the front part of the shark's head • ventral fin - each of the paired fins on the lower side of the body, near the head Shark Power Point • THE SHARK Goblin shark goblin shark Goblin/Frill sharks Epaulette Shark • Walks along sea bottom Epaulette Shark Hammerhead shark Helicoprion Helicoprion skeleton of a Megalodon • range from 4050 feet (about 12-15 metres) Previous much larger reconstructions of the shark's size, up to about 100 feet (30 m), are generally considered inaccurate Cladoselache Cookie Cutter Shark Cookie Cutter Shark Cookie Cutter Shark Osteichthyes • some bone in their skeleton and/or scales • bony operculum covering gill opening • lungs or a swim bladder Osteichthyes • Bony fish first appeared in the Silurian. They are thought to have a common ancestor with acanthodians. They are characterized by overlapping scales and a bony skeleton. An advanced bony fish, Class Osteichthyes, like the one shown here, differs in a number of ways from sharks and primitive bony fish. The spiracle is gone, pelvic fins have moved forward, the tail is symmetrical. As in chimaeras, the gills are covered by an operculum. Osteichthyes is the largest class of vertebrates with over 20,000 species. Subclass Sarcopterygii lungfish – lungs for gas exchange when lakes and rivers become stagnate these fish use lungs to breathe aire when river beds dry up can hibernate or lay dormant for six months or more will burrow in earth they will come out when it rains or river starts to flow Lungfish Coelancanths • – most recent fossil 70 • • million years old 1938, fishing, fish was identified as coelancanths – latineria chalumnae 80kg 1977 Latineria menadoensis • Latimeria chalumnae is a lobed-finned fish that was thought to be extinct for over 60 million years. • It is 5 feet in length, weighs approximately 80 kg, has color ranging from brown to dark blue, and body patterns are unique to the individual. Coelacanths, opportunistic predators, feed by standing on their head, swim backwards, and belly-up using their rosteral gland to locate their prey. Then it sucks its food into its hinged jaws. Coelancanths Coelancanths Picture of first coelacanth discovered (1938). Osteolepiforms – extinct Subclass Actinopterygii • ray finned fish – fins lack muscular lobes • usually posses swimbladders – regulate buoyancy Chondrosteans – most bony but cartilaginous – sturgeons and paddlefish • valued for their eggs • Most chondrostean species lived during the late Palaeozoic. There are only two chondrostean lineages that survive today, the paddlefish of Canada and China and the sturgeons of Europe, Asia and Canada. • Both lineages have secondarily lost a number of their actinopterygian characters: • scales lost on most of the body, • cartilaginous skeleton, • shark-like, heterocercal tail, • rostrum extending past the mouth, which forms the paddle of the paddlefish. • The earliest ray-finned fish were the chondrosteans, represented today only by the few types of fish shown here. They retain primitive features including thick scales, heterocercal tails and posteriorly placed pelvic fins. Most fish today are the more advanced teleosts with thin scales, homocercal tails and pelvic fins close to the anterior pectoral fins. Scales and tail types are discussed in the next two screens. • The scales of advanced bony fish are the vestiges of the bony armor of their ancestors. They consist of a thin layer of bone produced by the dermis of the skin. The scales are covered by the thin epidermis. • These are the types of caudal fins found in major groups of fish. Chondrosteans • Paddlefish • Lake Sturgeon Neopterygii – most living fish are members of this group – lepisosteus, garpike – amia, dogfish lepisosteus, garpike Neopterygii • Spiny dogfish Evolutionary success highly efficient respiratory system allows fish to extract oxygen from an environment that holds little oxygen efficient locomotion structures allows fish to move through a buoyant and high resistance to flow highly efficient sensory system, lateral line detects low pressure waves and electro reception efficient reproductive mechanism huge number of offspring Evolutionary Pressure Locomotion – stream lined – mucoid secretion lubricates body to reduce friction – forked caudal fin used for speed Nutrition & Digestion – larvae eat different than adult – suction (close operculum open mouth) Circulation & Gas Exchange closed circulatory system spiracles – water enters when mouth is closed counter current exchange mechanism swimbladders and lungs Indian climbing perch – almost entire life on land – Pneumatic sacs functions as lungs Lungfish, ancients rhipidistians The anatomy of fish gills, with many tiny folds called lamellae, greatly increases the surface area for gas exchange. As blood flows through capillaries in the lamellae, it moves in the opposite direction to the flow of oxygen-rich water. This greatly increases the amount of oxygen the blood can pick up by diffusion Buoyancy we floated because air filled lungs livers saturated with buoyant oils use fins to provide lift reduction of heavy tissue swim bladder controls volume of gas in its swim bladder Nervous & Sensory Functions brain and spinal cord sensory receptors widely distributed throughout body smell eyes lidless and round equilibrium, balance, hearing inner ears Lateral line system – sensory pits in the epidermis of the skin that connects to canals that run just below the epidermis – receptors there stimulated by water moving against them – Used to detect water currents, predatory prey, low frequency sounds Electroreception & Electric fish Electroreception – highly developed in sharks and rays Sharks have been known to find buried live flounder but not dead ones because of the electrical signals Electric fish generate electrical currents Electric eel – amazon shocks in excess of 500 volts ELECTRIC FISHES STRONGLY ELECTRIC SPECIES: marine electric rays, freshwater African catfish, freshwater electric eel WEAKLY ELECTRIC SPECIES: freshwater South American knifefish and African elephant fish ELECTRICALLY SENSITIVE SPECIES: Sharks, rays, skates and catfish Excretion and Osmoregulation Major function of the kidneys and gills of fish Excretory structures in the kidneys are called nephrons, filter nigrogenous wastes, ions, water Freshwater fish never drink, and only take water in when feeding this controls excess water buildup and ion loss (osmotic uptake is across gills) Marine fish – they drink water and eliminate excess ions by excretion, defecation, and active transport across gill surfaces. Cloaca Reproduction and Development 45 kg of caviar from a single 450 kg sturgeon imagine!! Most will not survive to reproduce Many eggs won’t be fertilized, washed up on shore, dried, predation Ways to increase chances of survival – Lay lots of eggs – Mating behavior, ensures fertilization, nesting Reproduce in schools Most fish are Oviparous (eggs) Elasmobranches – ovoviviparous – embryos develop in a modified oviduct of the female Artificial reproduction of trout Ovules are being obtained through abdominal pressure Weird Fish Facts Most lipstick contains fish scales. The ocean floor is completely dark. Very few fish can live there. The black angler fish is one that does. It carries its own lantern to lure Prey into its huge mouth. Bacteria that glow in the dark make the light Seahorse-Weedy Dragon Alligator Seahorse Potbelly Seahorse Leafy Dragon Catfish Flounder The summer flounder is a member of the family, Paralichthyidae. This lefteyed flatfish has both eyes on the left side of its body when viewed from above with the dorsal, or top fin, up. The eyed side of this fish is scattered with 10 to 14 eye-like spots which blend in with the ocean floor, while its belly or underside is white. Flounder Flounder Halibut H a l i b u t