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
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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