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Chondrichthyes: sharks, skates, rays and chimeras Craig Kasper, Ph. D. Zoology 1450 Chapter 12 Whats a chimera??

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Presentation on theme: "Chondrichthyes: sharks, skates, rays and chimeras Craig Kasper, Ph. D. Zoology 1450 Chapter 12 Whats a chimera??"— Presentation transcript:

1 Chondrichthyes: sharks, skates, rays and chimeras Craig Kasper, Ph. D. Zoology 1450 Chapter 12 Whats a chimera??

2 Sharks: the beginning…or the end?? Existence of elasmobranchs with little change is a testament to their evolutionary success and durability Existence of elasmobranchs with little change is a testament to their evolutionary success and durability Appear in fossil record in late Devonian, 500 mybp (perhaps earlier) Appear in fossil record in late Devonian, 500 mybp (perhaps earlier) Last class of fishes to appear in fossil record Last class of fishes to appear in fossil record Elasmobranch… plate or strap gill

3 Classification of Chondrichthyes Class Chondrichthyes (~850 spp.) Class Chondrichthyes (~850 spp.) –Subclass Elasmobranchi (~820 spp.) sharks, skates and rayssharks, skates and rays –Subclass Holocephali (~30 spp.) chimaeras, ratfisheschimaeras, ratfishes

4 Distinguishing Elasmobranch Traits cartilaginous skeleton cartilaginous skeleton absence of swim bladder absence of swim bladder heterocercal tail heterocercal tail placoid denticles - scales and teeth placoid denticles - scales and teeth spiracle present with 5-7 gill slits (no operculum) spiracle present with 5-7 gill slits (no operculum) urea retained for osmoregulation urea retained for osmoregulation spiral valve in intestine spiral valve in intestine males have clasper organs for internal fertilization males have clasper organs for internal fertilization embryonic development with physiological care embryonic development with physiological care oviparous, ovoviviparous, viviparous oviparous, ovoviviparous, viviparous jaw hyostylic (single connection of upper jaw to neurocranium - adds protrusibility) or amphistylic (two connection points - anterior and posterior) jaw hyostylic (single connection of upper jaw to neurocranium - adds protrusibility) or amphistylic (two connection points - anterior and posterior) teeth in rows, are constantly replaced teeth in rows, are constantly replaced eyes small eyes small

5 Holocephali: traits jaw holostylic (= autostylic = fused to neurocranium) jaw holostylic (= autostylic = fused to neurocranium) spiracle absent; gills covered by single operculum spiracle absent; gills covered by single operculum all oviparous all oviparous cloaca lacking - separate urogenital pore cloaca lacking - separate urogenital pore skin lacking scales; placoid spines skin lacking scales; placoid spines males with head claspers males with head claspers teeth are plate-like, non-deciduous teeth are plate-like, non-deciduous eyes large eyes large

6 Chondrichthian success story? Buoyancy control: fatty liver, no swim bladder and no energy required Buoyancy control: fatty liver, no swim bladder and no energy required Swimming adaptations: rigid fins instead of rays Swimming adaptations: rigid fins instead of rays Body covering: placoid scales, reduce drag (see Helfman, fig. 12.3) Body covering: placoid scales, reduce drag (see Helfman, fig. 12.3) Osmoregulation adaptations Osmoregulation adaptations Reproductive adaptations: self-sufficient young Reproductive adaptations: self-sufficient young Feeding adaptations Feeding adaptations Sensory system: tapetum lucetum, ampullae of Lorenzini Sensory system: tapetum lucetum, ampullae of Lorenzini Respiration effectiveness Respiration effectiveness Hey, if it aint broke…

7 Elasmobranch classification Superorder Galeomorphi Superorder Galeomorphi large, pelagic predators, blade-like teethlarge, pelagic predators, blade-like teeth –Heterodontiformes - horn sharks –Orectolobiformes - nurse sharks, whale sharks –Lamniformes - mackerel, mako, white sharks –Carcharhiniformes - requiem sharks (blacktip, whitetip, reef, bull), tiger sharks, basking sharks

8 Elasmobranch classification –Carcharhiniformes - requiem sharks (ground sharks) (blacktip, whitetip, reef, bull), tiger sharks, basking sharks –Ground sharks feature an anal fin, two dorsal fins, an elongated snout, and a long mouth that reaches behind the eyes, with teeth ranging from small and cuspidate to large and bladelike. They have a third eyelid as well.

9 Heterodontiformes - horn sharks

10 Orectolobiformes - whale sharks Rhincodon typus

11 Orectolobiformes - whale sharks Rhincodon typus

12 Orectolobiformes – nurse sharks Ginglymostoma cirratum Ginglymostoma cirratum

13 Lamniformes - mackerel, mako, white sharks Mako Great White, Carcharodon carcharias Mako Great White Isurus oxyrinchus

14 Carcharhiniformes - requiem sharks (blacktip) blacktip shark Carcharhinus limbatus Carcharhinus limbatus

15 Carcharhiniformes - requiem sharks (whitetip) Triaenodon obesus

16 Carchariniformes – bull sharks Carcharhinus leucas copyright FLMNH

17 Carchariniformes – tiger sharks Galeocerdo cuvier © George Burgess

18 Carchariniformes – basking sharks Cetorhinus maximus

19 Superorder Squatinomorphi Superorder Squatinomorphi –Squatiniformes-angel sharks bottom-oriented, enlarged pelvic fins, spike-like teethbottom-oriented, enlarged pelvic fins, spike-like teeth Atlantic Angel Shark, Squatina dumeril

20 Superorder Squalomorphi Superorder Squalomorphi smaller, pelagic and benthic sharks, feed on smaller prey, some with pointed teeth, some with pavement teethsmaller, pelagic and benthic sharks, feed on smaller prey, some with pointed teeth, some with pavement teeth –Squaliformes - dogfish sharks –Hexanchiformes - six & seven-gill sharks (cow sharks) –Pristiophoriformes - saw sharks

21 Squaliformes Squaliformes dogfish sharks dogfish sharks Spiny dogfish-Squalus acanthus Adipose spine

22 Hexanchiformes - six & seven-gill sharks (cow sharks) Sevengill Shark Heptranchias perlo

23 Pristiophoriformes - saw sharks

24 Superorder Batoidea (Rajimorphi) Superorder Batoidea (Rajimorphi) benthic or pelagic; pectoral fins enlarged, fused with head; gill slits ventral; spiracle large; pavement teethbenthic or pelagic; pectoral fins enlarged, fused with head; gill slits ventral; spiracle large; pavement teeth –Myliobatiformes - sting rays, eagle & manta rays, butterfly rays –Rajiformes - skates –Torpediniformes - electric rays

25 Myliobatiformes - sting rays eagle & manta rays eagle & manta rays butterfly rays butterfly rays

26 Rajiformes - skates

27 Skate or Ray...whats the difference? –Skates (order Rajiformes) –pelvic fin divided into two lobes –pelvic fin divided into two lobes –stocky tail w/o stinging spine –stocky tail w/o stinging spine –enlarged, thorn-like scales ('bucklers') along the midline of back –males have rows of enlarged scales near the eyes and wingtips –Rays (order Myliobatiformes): – one-lobed pelvic fin – one-lobed pelvic fin –whip-like tail, usually with stinging spine –whip-like tail, usually with stinging spine –no bucklers along back or tail –no bucklers along back or tail

28 Pristiformes - sawfishes

29 Torpediniformes - electric rays

30 Spotted ratfish Hydrolagus colliei Family: chimaeridae Identification: Broad, flat, duckbill shaped snout containing incisor shaped teeth. Prominent, venomous spine at leading edge of dorsal fin. Tapering tail constitutes almost half overall length. Coloration brown or grey with white spots. Skin smooth and scaleless. Can give off an iridescent, silvery sheen. Fins grey or dark. Identification: Broad, flat, duckbill shaped snout containing incisor shaped teeth. Prominent, venomous spine at leading edge of dorsal fin. Tapering tail constitutes almost half overall length. Coloration brown or grey with white spots. Skin smooth and scaleless. Can give off an iridescent, silvery sheen. Fins grey or dark. Size: up to 97cm in length. Size: up to 97cm in length.

31 More Ratfish!


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