Chondrichthyes: Chondrichthyes: sharks, skates, rays and chimeras sharks, skates, rays and chimeras

Craig Kasper, Ph. D. Craig Kasper, Ph. D. Zoology 1450 Zoology 1450

Chapter 12Chapter 12

What’s a chimera??

Sharks: the beginning…or the end??Sharks: the beginning…or the end??

Existence of elasmobranchs with little change is a Existence of elasmobranchs with little change is a testament to their evolutionary success and durabilitytestament to their evolutionary success and durability

Appear in fossil record in late Devonian, 500 mybp Appear in fossil record in late Devonian, 500 mybp (perhaps earlier)(perhaps earlier)

Last class of fishes to appear in fossil recordLast class of fishes to appear in fossil record

Elasmobranch… plate or strap gill

Classification of ChondrichthyesClassification of Chondrichthyes

Class Chondrichthyes (~850 spp.)Class Chondrichthyes (~850 spp.)

– Subclass Elasmobranchi (~820 spp.)Subclass Elasmobranchi (~820 spp.)• sharks, skates and rayssharks, skates and rays

– Subclass Holocephali (~30 spp.)Subclass Holocephali (~30 spp.)• chimaeras, ratfisheschimaeras, ratfishes

Distinguishing Elasmobranch TraitsDistinguishing Elasmobranch Traits

cartilaginous skeletoncartilaginous skeleton absence of swim bladderabsence of swim bladder heterocercal tailheterocercal tail placoid denticles - scales and teethplacoid 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 osmoregulationurea retained for osmoregulation spiral valve in intestinespiral valve in intestine males have clasper organs for internal fertilizationmales have clasper organs for internal fertilization embryonic development with physiological careembryonic development with physiological care

oviparous, ovoviviparous, viviparousoviparous, ovoviviparous, viviparous jaw hyostylic (single connection of upper jaw to neurocranium - adds jaw hyostylic (single connection of upper jaw to neurocranium - adds

protrusibility) or amphistylic (two connection points - anterior and protrusibility) or amphistylic (two connection points - anterior and posterior)posterior)

teeth in rows, areteeth in rows, are constantly replacedconstantly replaced eyes smalleyes small

Holocephali: traitsHolocephali: traits

jaw holostylic (= autostylic = fused to neurocranium)jaw holostylic (= autostylic = fused to neurocranium)spiracle absent; gills covered by single operculumspiracle absent; gills covered by single operculumall oviparousall oviparouscloaca lacking - separate urogenital porecloaca lacking - separate urogenital poreskin lacking scales; placoid spinesskin lacking scales; placoid spinesmales with head claspersmales with head claspers teeth are plate-liketeeth are plate-like, , non-deciduousnon-deciduouseyes largeeyes large

Chondrichthian success story?Chondrichthian success story? Buoyancy control: fatty liver, no swim bladder and no energy requiredBuoyancy control: fatty liver, no swim bladder and no energy required

Swimming adaptations: rigid fins instead of raysSwimming 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 adaptationsOsmoregulation adaptations

Reproductive adaptations: self-sufficient youngReproductive adaptations: self-sufficient young

Feeding adaptationsFeeding adaptations

Sensory system: tapetum lucetum, ampullae of LorenziniSensory system: tapetum lucetum, ampullae of Lorenzini

Respiration effectivenessRespiration effectiveness

Hey, if it ain’t broke…

Elasmobranch classificationElasmobranch classificationSuperorder GaleomorphiSuperorder Galeomorphi

• large, pelagic predators, blade-like teethlarge, pelagic predators, blade-like teeth

– Heterodontiformes - horn sharksHeterodontiformes - horn sharks– Orectolobiformes - nurse sharks, whale sharksOrectolobiformes - nurse sharks, whale sharks– Lamniformes - mackerel, mako, white sharksLamniformes - mackerel, mako, white sharks– Carcharhiniformes - requiem sharks (blacktip, Carcharhiniformes - requiem sharks (blacktip,

whitetip, reef, bull), tiger sharks, basking whitetip, reef, bull), tiger sharks, basking sharkssharks

Heterodontiformes - horn sharks

Orectolobiformes - whale sharksOrectolobiformes - whale sharks

Rhincodon typusRhincodon typus

Orectolobiformes –Orectolobiformes –

nurse sharksnurse sharks

Ginglymostoma cirratumGinglymostoma cirratum

Lamniformes - mackerel, mako, white sharksLamniformes - mackerel, mako, white sharks

MakoMako Great White, Great White, Carcharodon carchariasCarcharodon carcharias

Mako Great WhiteGreat White

Isurus oxyrinchusIsurus oxyrinchus

Carcharhiniformes - Carcharhiniformes - requiem sharks (blacktip)requiem sharks (blacktip)

blacktip shark

Carcharhinus limbatusCarcharhinus limbatus

Carcharhiniformes - requiem sharks (whitetip)

Triaenodon obesus

Carchariniformes – bull sharksCarcharhinus leucasCarcharhinus leucas

copyright FLMNH

Carchariniformes – tiger sharksCarchariniformes – tiger sharksGaleocerdo cuvierGaleocerdo cuvier

© George Burgess

Carchariniformes – basking sharksCarchariniformes – basking sharks

Cetorhinus maximus Cetorhinus maximus

Superorder SquatinomorphiSuperorder Squatinomorphi– Squatiniformes-angel sharksSquatiniformes-angel sharks

• bottom-oriented, enlarged pelvic fins, bottom-oriented, enlarged pelvic fins, spike-like teethspike-like teeth

Atlantic Angel Shark, Atlantic Angel Shark, Squatina dumerilSquatina dumeril

Superorder SqualomorphiSuperorder Squalomorphi• smaller, pelagic and benthic sharks, feed on smaller smaller, pelagic and benthic sharks, feed on smaller

prey, some with pointed teeth, some with pavement prey, some with pointed teeth, some with pavement teethteeth

– Squaliformes - dogfish sharksSqualiformes - dogfish sharks– Hexanchiformes - six & seven-gill sharks (cow Hexanchiformes - six & seven-gill sharks (cow

sharks)sharks)– Pristiophoriformes - saw sharksPristiophoriformes - saw sharks

Squaliformes Squaliformes dogfish sharksdogfish sharks

Spiny dogfish-Squalus acanthus

Adipose spine

Hexanchiformes - six & seven-gill sharks (cow sharks)Hexanchiformes - six & seven-gill sharks (cow sharks)

Sevengill SharkSevengill Shark Heptranchias perloHeptranchias perlo

Pristiophoriformes - saw sharksPristiophoriformes - saw sharks

Superorder Batoidea (Rajimorphi)Superorder Batoidea (Rajimorphi)• benthic or pelagic; pectoral fins enlarged, fused with benthic or pelagic; pectoral fins enlarged, fused with

head; gill slits ventral; spiracle large; pavement head; gill slits ventral; spiracle large; pavement teethteeth

– Myliobatiformes - sting rays, eagle & manta Myliobatiformes - sting rays, eagle & manta rays, butterfly raysrays, butterfly rays

– Rajiformes - skatesRajiformes - skates– Pristiformes - sawfishesPristiformes - sawfishes– Torpediniformes - electric raysTorpediniformes - electric rays

Myliobatiformes - sting raysMyliobatiformes - sting rays

eagle & manta rayseagle & manta rays

butterfly raysbutterfly rays

Rajiformes - skatesRajiformes - skates

Skate or Ray...what’s the difference?Skate or Ray...what’s the difference?– Skates (order Rajiformes)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 enlarged, thorn-like scales ('bucklers') along the midline of backmidline of back

– males have rows of enlarged scales near the eyes and males have rows of enlarged scales near the eyes and wingtipswingtips

– Rays (order Myliobatiformes):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 

Pristiformes - sawfishesPristiformes - sawfishes

Torpediniformes - electric raysTorpediniformes - electric rays