Transcript Fish
Class Agnatha
Jawless fish.
Living species include lampreys and hagfish.
Ostracoderms – armor plates of bony tissue
Placoderms – mineral hardened backbone and jaw
Significant because they may represent the ancestor
of bony fish/sharks.
Key Innovations Bony Fish
Bone tissue with a vertebrae
part of inner skeleton, paired with muscle
segments
Jaws started trend towards more complex
sensory organs and nervous systems
Paired fins
Key Innovations Bony Fish
Gills – large surface area for water to diffuse
into blood vessels
Don't function out of water
Lungs – supplemented and then replaced gills
Increase effiency
Characteristics of Cartilaginous
Fish
Class Chondrichthyes includes sharks, rays and
their close relatives.
jawed fish, that lack a swim bladder, and
cartilaginous skeletons.
5-7 gill silts, stream lined body
“conveyor belt” of teeth.
Modified scales
Sharks and Rays
5-6
Sharks and rays have other interesting
characteristics:
lateral lines – lines of sensory hair along the
length of the body, detect water motion and
vibrations.
electroreception – the ability to sense minute
electricity created by muscles and nerves.
ampullae of Lorenzini - visible pits near their
snouts used to detect the electrical current.
Osteichthyes
Ray-finned fish – flexible fin with support from
skin and scales
Bony endoskeleton
Swim bladder – exchanges gases with blood to
help with floatation (gulp air)
Characteristics of Bony Fish
Characteristics for life on the reef and for life in
the open ocean:
5-8
lateral lines that detect water motion and
vibrations.
open ocean fish have a torpedo-like
streamlined shape to minimizes drag and
turbulence.
Lobe-Finned
Coelacanths only surviving group
Ventral fin are extensions of body with skeletal
support
Lungfish
Have gills and 1-2 small outpouching of gut wall
Sacs help take in O2 and remove CO2
Must surface and gulp air (will drown if held under
water)
Ancestor to tetrapod??