Kingdom: Animalia Phylum: Chordata Subphylum: Craniata
Infraphylum: Vertebrata Classification
Slide 4
Largest and most successful group of chordates Notochord:
replaced by bony or cartilaginous vertebrae (the backbone) Anterior
end Develops into a three-part brain Forebrain, midbrain, &
hindbrain Sense organs Display high degree of cephalization Large
number of fossils (thanks to the endoskeleton) Evolutionary
Perspective
Slide 5
Began evolving 500 million years ago Display a variety of
colors, shapes, & sizes Occupy all aquatic environments Divided
into two infraphyla: Hyperotreti (hagfish) & Vertebrata (all
other fish) Until recently, hagfish & lampreys were classified
together Lampreys actually are closely related to cartilaginous
fish Zoologists are still unaware if fish were the first craniates
(animals with skulls) (more than likely hagfish were the first to
evolve) Evolution of Fish
Slide 6
20 different species Brains enclosed by a fibrous sheath Body
is supported by cartilaginous bars Mouth is surrounded by sensory
tentacles Slime glands produce a large amount of slime (hard to
grab the animal if it is covered in slime) * Hagfish slimeHagfish
slime Live in cold-water marine habitats Both Northern &
Southern hemispheres Bury themselves in the sand and mud Eat
soft-bodied invertebrates & dead/dying animals Can also swim
into a fishs mouth and eat the organs while the fish is still alive
Some hagfish are endangered due to overfishing for their soft,
tough skin Infraphylum Hyperotreti Class Myxini Hagfish!!!
Slide 7
Found in marine & freshwater environments Temperate regions
Adults prey on other fishes Larvae filter feed Mouth is modified
into suckers Surrounded by lips with sensory & attachment
functions Teeth line the mouth & cover a movable tongue
Lampreys use their mouths to scrape away scales Secrete an
anticoagulant to suck blood from their prey Lamprey video
Infraphylum Vertebrata Class Petromyzontida Lampreys!!!
Slide 8
Not all lampreys are predators Brook lampreys feed only as
larvae (for 3 years) As adults, they do not eat. They simply
reproduce and then die. Adult lampreys live in either the ocean or
the Great Lakes Lampreys travel to freshwater streams to spawn
(mate & lay eggs) Once they have constructed their nest, the
females attach to stone with their mouths The males attach to the
female heads with their mouths during mating. Eggs are shed in
batches over the course of a few hours- External fertilization
Infraphylum Vertebrata Class Petromyzontida Lampreys!!!
Slide 9
Includes sharks, skates, rays, & ratfishes Mostly
carnivores or scavengers Usually marine Skeleton- made out of
cartilage Mouths are highly developed for BITING!!! Skin- covered
in placoid scales Gives the skin a tough, sandpaper feel Some dried
shark skin is used as sandpaper We use this same design for some
swim wear (designed to add speed) Infraphylum Vertebrata Class
Chondrichthyes Cartilaginous fish!!! NB #137
Slide 10
820 different species Sharks evolved from early jawed fishes
~375 million years ago Class Chondrichthyes Sublcass Elasmobranchii
Sharks, skates & rays!!! They are sometimes considered to be
more primitive fish Lack swim bladder, gill cover, & bony
skeleton They are not primitive, but they simply adapted to
different selection pressures
Slide 11
Successful predators in the ocean Teeth- several rows of teeth
As the teeth become useless, newer teeth move into the position
from the inside jaw to replace that tooth Rapid teeth replacement
in young sharks (new row every seven or eight days) Adapted to the
sharks prey possibly shearing prey or crushing Range in size from 1
m (dogfish sharks) to over 10 m (whale sharks) The largest sharks
are filter feeders *Fiercest and most feared sharks are.the GREAT
WHITE SHARKS and the MAKO SHARKS!!!! Class Chondrichthyes Subclass
Elasmobranchii Sharks!!!!
Slide 12
Shark Facts The bull shark is known for swimming into rivers.
One was even found as far as Alton, Illinois in the Mississippi
River. The oceanic whitetip sharks are responsible for more shark
attacks than any other species You are 1,000 times more likely to
drown in the sea than you are to be bitten by a shark. The chance
of being killed by a shark is one in 300 million. The chance of
being killed by airplane parts falling from the sky is one in 10
million. Sharks wounds heal quickly and they rarely get tumors.
Sharks can smell one drop of blood in a million drops of water.
Class Chondrichthyes Subclass Elasmobranchii Sharks!!!! For more
shark facts visit www.sharkfacts.org
Slide 13
Specialized for life on the ocean floor Usually live in shallow
water Use their blunt teeth to feed on invertebrates Pectoral fins
are modified into wings Move through dorsoventral muscular waves
Can camouflage with the ground Sting rays have a tail modified into
a defensive lash (contains venom) Manta rays have horn-shaped
cephalic fins Electric rays produce an electric discharge for
defense that ranges from 8-220 volts Class Chondrichthyes Subclass
Elasmobranchii Rays & Skates!!!
Slide 14
30 different species Possess a gill cover (called an operculum)
Have teeth modified into plates for crushing shells of mollusks
Ratfish do NOT have scales Class Chondrichthyes Subclass
Holocephali Chimaera or ratfish!!!