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

What’s a chimera??
Chondrichthyes:
sharks, skates, rays and chimeras
Craig Kasper, Ph. D.
Zoology 1450
Chapter 12
Sharks: the beginning…or the end??
 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)
 Last class of fishes to appear in fossil record
Elasmobranch…
plate or strap gill
Classification of Chondrichthyes
Class Chondrichthyes (~850 spp.)
– Subclass Elasmobranchi (~820 spp.)
• sharks, skates and rays
– Subclass Holocephali (~30 spp.)
• chimaeras, ratfishes
Distinguishing Elasmobranch Traits
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cartilaginous skeleton
absence of swim bladder
heterocercal tail
placoid denticles - scales and teeth
spiracle present with 5-7 gill slits (no operculum)
urea retained for osmoregulation
spiral valve in intestine
males have clasper organs for internal fertilization
embryonic development with physiological care
 oviparous, ovoviviparous, viviparous
 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
 eyes small
Holocephali: traits
jaw holostylic (= autostylic = fused to neurocranium)
spiracle absent; gills covered by single operculum
all oviparous
cloaca lacking - separate urogenital pore
skin lacking scales; placoid spines
males with head claspers
teeth are plate-like, non-deciduous
eyes large
Chondrichthian success story?
 Buoyancy control: fatty liver, no swim bladder and no energy required
 Swimming adaptations: rigid fins instead of rays
 Body covering: placoid scales, reduce drag (see Helfman, fig. 12.3)
 Osmoregulation adaptations
 Reproductive adaptations: self-sufficient young
 Feeding adaptations
 Sensory system: tapetum lucetum, ampullae of Lorenzini
 Respiration effectiveness
Hey, if it ain’t broke…
Elasmobranch classification
Superorder Galeomorphi
• large, pelagic predators, blade-like teeth
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Heterodontiformes - horn sharks
Orectolobiformes - nurse sharks, whale sharks
Lamniformes - mackerel, mako, white sharks
Carcharhiniformes - requiem sharks (blacktip,
whitetip, reef, bull), tiger sharks, basking
sharks
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.
Heterodontiformes - horn sharks
Orectolobiformes - whale sharks
Rhincodon typus
Orectolobiformes - whale sharks
Rhincodon typus
Orectolobiformes –
nurse sharks
Ginglymostoma cirratum
Lamniformes - mackerel, mako, white sharks
Great White
Mako
Isurus oxyrinchus
Mako
Great White, Carcharodon carcharias
Carcharhiniformes requiem sharks (blacktip)
Carcharhinus limbatus
blacktip shark
Carcharhiniformes - requiem sharks (whitetip)
Triaenodon obesus
Carchariniformes – bull sharks
Carcharhinus leucas
copyright FLMNH
Carchariniformes – tiger sharks
Galeocerdo cuvier
© George Burgess
Carchariniformes – basking sharks
Cetorhinus maximus
Superorder Squatinomorphi
– Squatiniformes-angel sharks
• bottom-oriented, enlarged pelvic fins,
spike-like teeth
Atlantic Angel Shark, Squatina dumeril
Superorder Squalomorphi
• smaller, 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
Spiny dogfish-Squalus acanthus
Squaliformes
dogfish sharks
Adipose spine
Sevengill Shark
Heptranchias perlo
Hexanchiformes - six & seven-gill sharks (cow sharks)
Pristiophoriformes - saw sharks
Superorder Batoidea (Rajimorphi)
• benthic 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
Myliobatiformes - sting rays
eagle & manta rays
butterfly rays
Rajiformes - skates
Skate or Ray...what’s the difference?
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Skates (order Rajiformes)
pelvic fin divided into two lobes
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
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Rays (order Myliobatiformes):
one-lobed pelvic fin
whip-like tail, usually with stinging spine
no bucklers along back or tail
Pristiformes - sawfishes
Torpediniformes - electric rays
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.
 Size: up to 97cm in length.
More Ratfish!