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Diversity of Fishes II. Fish Taxa Diversity. Phylum Chordata Superclass Agnatha Class Pteraspidomorphi † Class Myxini (?) Class Cephalaspidomorphi Superclass Gnathostomata Class Placodermi † Class Acanthodii † Class Chondrychthyes Class Sarcopterygii Class Actinopterygii.
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Fish Taxa Diversity • Phylum Chordata • Superclass Agnatha • Class Pteraspidomorphi† • Class Myxini (?) • Class Cephalaspidomorphi • Superclass Gnathostomata • Class Placodermi† • Class Acanthodii† • Class Chondrychthyes • Class Sarcopterygii • Class Actinopterygii
Superclass Gnathostomata • Class Placodermi† • Bony anterior plates • Jawed with depressed flattened bodies • Pectoral and pelvic fins
Superclass Gnathostomata Class Chondrichthyes • Subclass Elasmobranchii • Sharks, skates and rays • Cartilaginous skeleton, placoid scales, replacement dentition, internal fertilization and multiple gill slits. • Subclass Holocephali • Chimaeras or ratfishes • Upper jaws fused to braincase, cartilaginous skeleton, single gill cover, separate anal and urogenital openings, erectable dorsal spine
Subclass Elasmobranchii • Around 800 species of sharks and rays • Cartilaginous skeleton with calcifications • Teeth replaced serially • Soft un-segmented fins (ceratotrichia) • FIVE, six or seven external gill slits (spiracule) • Buoyant livers and spiral valve intestines • Internal fertilization (pelvic fin claspers) • Osmotic regulation through metabolic waste products (urea and Trimethylamine oxide-TMAO) • Single cloaca
Subclass Elasmobranchii • Predators (or scavengers) • Mainly marine habitats • Slow metabolism and slow growth • Internal fertilization • Low fecundity (few & large young) • Ovipary • Ovovivipary • Vivipary
Subclass Elasmobranchii • Order Heterodontiformes (8 spp, bullhead and horn sharks) • Family Heterodontidae • 2 dorsal fins each with a spine
Subclass Elasmobranchii • Order heterodontiformes (8 spp, bullhead and horn sharks) • Family Heterodontidae • 2 dorsal fins each with a spine • Order Orectolobiformes (31 spp, carpet sharks) • 7 families • 2 dorsal fins with no spines, short mouth • Includes wobbegons, nurse sharks and whale sharks
Subclass Elasmobranchii • Order heterodontiformes (8 spp, bullhead and horn sharks) • Family Heterodontidae • 2 dorsal fins each with a spine • Order Orectolobiformes (31 spp, carpet sharks) • 7 families • 2 dorsal fins with no spines, short mouth • Includes wobbegons, nurse sharks and whale sharks • Order Carcharhiniformes (210 spp, ground and requiem sharks) • 7 families • 2 dorsal fins with no spines, medium mouths • Includes cat sharks, gray sharks, tiger sharks, blue sharks, hammerheads
Subclass Elasmobranchii (cont.) • Order Lamniformes (16 spp, mackerel sharks) • 7 families • 2 dorsal fins with no spines, large mouths • Includes great white, mako, basking sharks, thresher sharks and megamouth • Order Hexanchiformes (5 spp, cow & frill sharks) • 2 families • One dorsal fin, six or seven gill slits • Order Squaliformes (74 spp, dogfish sharks) • 4 families • 2 dorsal fins with or without spines, no anal fin • Includes dogfish and cookie-cutter sharks sharks • Order Squatiniformes (12 spp, angel sharks) • 1 family • Ray-like body, terminal mouth
Subclass Elasmobranchii (cont.) • Order Pristiophoridae (5 spp, Sawsharks) • Shark-like body, flat blade snout with lateral teeth of unequal size • Order Rajiformes (456 spp, 13 families) • Ventral gill openings, dorsal eyes, depressed bodies, advanced pectoral fins attached to the head • Includes sawfishes, guitarfishes, electric rays, skates, stingrays, butterfly rays, eagle rays and Manta rays
Sharks Orders
Rays & Skates Order Rajiformes
Subclass Holocephali • Chimaeras or ratfishes (58 spp.) • 3 Families • Upper jaws fused to braincase, cartilaginous skeleton, single gill cover, separate anal and urogenital openings, erectable dorsal spine (poisonous) • Breath through nostrils • Male have clasper on head (internal fertilization).
1580-2005 Map of World's Confirmed Unprovoked Shark Attacks (N=2,035)
Risk of Shark attack in US SHARKS Hits/Att Deaths Att Deaths Lightning (year) 179.7* 44.9* 11.4 0.5 Alligator 365 13 503 8 Tornadoes 1036 69 213 2 Bicycles 4476 107 37 1
Animal Related Deaths - USA Animal Average Number of Fatalities Per Year • Deer (Vehicular Collisions) 130 • Dogs 18 • Snakes 15 • Mountain Lions 0.6 • Sharks 0.4