2 ClassificationKingdom: Animalia Phylum: Chordata Subphylum: Craniata Infraphylum: Vertebrata
3 Evolutionary Perspective Largest and most successful group of chordatesNotochord: replaced by bony or cartilaginous vertebrae (the backbone)Anterior endDevelops into a three-part brainForebrain, midbrain, & hindbrainSense organsDisplay high degree of cephalizationLarge number of fossils (thanks to the endoskeleton)
4 Evolution of Fish Began evolving 500 million years ago Display a variety of colors, shapes, & sizesOccupy all aquatic environmentsDivided into two infraphyla: Hyperotreti (hagfish) & Vertebrata (all other fish)Until recently, hagfish & lampreys were classified togetherLampreys actually are closely related to cartilaginous fishZoologists are still unaware if fish were the first craniates (animals with skulls)(more than likely hagfish were the first to evolve)
5 Infraphylum Hyperotreti Class Myxini Hagfish!!!20 different speciesBrains enclosed by a fibrous sheathBody is supported by cartilaginous barsMouth is surrounded by sensory tentaclesSlime glands produce a large amount of slime (hard to grab the animal if it is covered in slime)* Hagfish slimeLive in cold-water marine habitatsBoth Northern & Southern hemispheresBury themselves in the sand and mudEat soft-bodied invertebrates & dead/dying animalsCan also swim into a fish’s mouth and eat the organs while the fish is still aliveSome hagfish are endangered due to overfishing for their soft, tough skin
6 Infraphylum Vertebrata Class Petromyzontida Lampreys!!!Found in marine & freshwater environmentsTemperate regionsAdults prey on other fishesLarvae filter feedMouth is modified into suckersSurrounded by lips with sensory & attachment functionsTeeth line the mouth & cover a movable tongueLampreys use their mouths to scrape away scalesSecrete an anticoagulant to suck blood from their preyLamprey video
7 Infraphylum Vertebrata Class Petromyzontida Lampreys!!!Not all lampreys are predatorsBrook lampreys feed only as larvae (for 3 years)As adults, they do not eat. They simply reproduce and then die.Adult lampreys live in either the ocean or the Great LakesLampreys travel to freshwater streams to spawn (mate & lay eggs)Once they have constructed their nest, the females attach to stone with their mouthsThe males attach to the female heads with their mouths during mating.Eggs are shed in batches over the course of a few hours- External fertilization
8 Infraphylum Vertebrata Class Chondrichthyes Cartilaginous fish!!!NB #137Includes sharks, skates, rays, & ratfishesMostly carnivores or scavengersUsually marineSkeleton- made out of cartilageMouths are highly developed for BITING!!!Skin- covered in “placoid” scalesGives the skin a tough, sandpaper feelSome dried shark skin is used as sandpaperWe use this same design for some swim wear (designed to add speed)
9 Class Chondrichthyes Sublcass Elasmobranchii Sharks, skates & rays!!!820 different speciesSharks evolved from early jawed fishes ~375 million years agoThey are sometimes considered to be more primitive fishLack swim bladder, gill cover, & bony skeletonThey are not primitive, but they simply adapted to different selection pressures
10 Class Chondrichthyes Subclass Elasmobranchii Sharks!!!!Successful predators in the oceanTeeth- several rows of teethAs the teeth become useless, newer teeth move into the position from the inside jaw to replace that toothRapid teeth replacement in young sharks (new row every seven or eight days)Adapted to the shark’s preypossibly shearing prey or crushingRange in size from 1 m (dogfish sharks) to over 10 m (whale sharks)The largest sharks are filter feeders*Fiercest and most feared sharks are….the GREAT WHITE SHARKS and the MAKO SHARKS!!!!
11 Class Chondrichthyes Subclass Elasmobranchii Sharks!!!!Shark FactsThe bull shark is known for swimming into rivers. One was even found as far as Alton, Illinois in the Mississippi River.The oceanic whitetip sharks are responsible for more shark attacks than any other speciesYou are 1,000 times more likely to drown in the sea than you are to be bitten by a shark.The chance of being killed by a shark is one in 300 million. The chance of being killed by airplane parts falling from the sky is one in 10 million.Sharks’ wounds heal quickly and they rarely get tumors.Sharks can smell one drop of blood in a million drops of water.For more shark facts visit
12 Class Chondrichthyes Subclass Elasmobranchii Rays & Skates!!!Specialized for life on the ocean floorUsually live in shallow waterUse their blunt teeth to feed on invertebratesPectoral fins are modified into “wings”Move through dorsoventral muscular wavesCan camouflage with the groundSting rays have a tail modified into a defensive lash (contains venom)Manta rays have horn-shaped cephalic finsElectric rays produce an electric discharge for defense that ranges from volts
13 Class Chondrichthyes Subclass Holocephali Chimaera or ratfish!!!Class Chondrichthyes Subclass Holocephali30 different speciesPossess a gill cover (called an operculum)Have teeth modified into plates for crushing shells of mollusksRatfish do NOT have scales
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