ELASMOBRANCHES sharks, rays, skates SUPERCLASS AGNATHA Class Myxini Order Myxiniformes (hagfishes) Class Cephalaspidomorphi Order Petromyzontiformes (lamprey) SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Holocephali Order Chimaeriformes (chimaeras) Subclass Elasmobranchii 9+ orders (sharks, rays, skates) Class Sarcopterygii Subclass Coelacanthimorpha Order Coelacanthiformes (coelacanths) Subclass Dipnoi Order Ceratodontiformes (lungfish) Order Lepidosireniformes (S. American, African lungfish) Class Actinopterygii - (rayfins, higher bony fishes) Subclass Chondrostei Order Polypteriformes (birchirs, reedfish) Order Acipenseriformes (sturgeons, paddlefishes) Subclass Neopterygii Order Semionotoformes (Lepisosteiformes) (gars) Order Amiiformes (bowfin) Division Teleostei 35-38 orders (modern body fishes) Taxonomic resources: Chondrichthyes http://www.elasmo-research.org/education/shark_profiles/heterodontiformes.htm Super-orders Squalomorphii Rajomorphii (Batoidea) Galeomorphii Orders Chimaeriformes Hexanchiformes Squaliformes Pristiophoriformes Squatiniformes Pristiformes Rhinobatiformes Torpediniformes Rajiformes Myliobatiformes Heterodontiformes Orectolobiformes Lamniformes Carcharhiniformes # species ~11 species 154 species some dorso-ventrally flattened 555-573 species dorso-ventrally flattened Swim with fins, not tail 342+ species most of the largest species SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii • • • • • • • • • 5 to 7 gill openings rigid dorsal fins skeleton may be partially calcified upper jaw not fused to cranium spiracle present – (modified gill slit, used for breathing in benthic spp.) cloaca present (combined urinary, intestinal, and reproductive vent) swim bladder absent placoid scales (dermal denticles) present or absent internal fertilization males usually have pelvic intromittent organs (myxopterygia) and claspers • fins supported by soft, unsegmented rays (ceratotrichia) SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii Order Hexanchiformes (frill sharks, cow sharks) 6-7 gill openings anal fin; 1 dorsal fin, no spines Squalean sharks SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii Squalean sharks Order Squaliformes (dogfish, cookie-cutter, bramble, sleeper) 5-6 gill openings no anal fin (usually); 2 dorsal fins, may have spine SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii Squalean sharks Order Squaliformes (dogfish, cookie-cutter, bramble, sleeper) Bramble shark dogfish SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii Squalean/batoid sharks Order Pristiophoriformes (saw sharks) rostrum is long, flat blade with teeth on each edge; large barbels 5 or 6 gill openings Courtesy: www.pbs.org SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii Squalean/batoid sharks Order Squatiniformes (angel sharks) flattened, large pelvic and pectoral fins eyes dorsal 2 dorsal fins, not spiny swims using tail SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii Pristiformes (sawfishes) Squalean/batoid sharks Convergent evolution…… Pristiformes Pristiophoriformes (saw shark) Smaller; gills on sides of head, sensory barbels on snout (sawfish) Gills on ventral surface, no barbels, SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii Rhinobatiformes - guitarfishes Squalean/batoid sharks SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii Torpediniformes – electric ray batoids SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii batoids Rajiformes • body dorso-ventrally flattened, disc-shaped • eyes dorsal • no anal fin; tail mostly or all separate from body • pectoral fin origin connected with head • swim with undulations of enlarged pectoral fins • internal fertilization; oviparous (skates) or oviviparous (all others) Rajidae - skates SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii Rajiformes • mouth and gill openings ventral • teeth ‘pavementlike’ batoids SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii batoids Myliobatiformes ( eagle rays, manta rays, bat rays, stingrays) manta ray eagle ray Stingray – poison spines some freshwater species Butterfly ray SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii galeomorph sharks Heterodontiformes (bullhead sharks) 2 dorsals, w. leading spine on each (not in Bond) sharp teeth in front of mouth, molariform at the back Port Jackson shark SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii galeomorph sharks Orectolobiformes (carpet, nurse sharks) 2 dorsals, no spines whale shark Courtesy: www. pescanet.com SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii galeomorph sharks Orectolobiformes (carpet, nurse sharks) 2 dorsals, no spines tasseled wobbegong SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii galeomorph sharks Lamniformes (thresher, basking, megamouth) 2 dorsals, anal, no spines SUPERCLASS GNATHOSTOMATA Class Chondrichthyes Subclass Elasmobranchii galeomorph sharks Carcharhiniformes (hammerheads, ground sharks, cat sharks, blacktip) 2 dorsals, anal, no spines Courtesy: http://www.pbs.org Courtesy: National Geographic