Class: Chondrichthyes
Major Characteristic Features
1) movable jaws with
well-developed
teeth
2) paired lateral fins
3) placoid scales
which feels like
sandpaper
Class: Chondrichthyes
Scales and Teeth • placoid scales are also
known as dermal
denticles
• scales have the same
composition as teeth
• teeth are continually
shed and replaced by
the rows behind
Class: Chondrichthyes
Buoyancy
• shark liver aids in buoyancy because it contains oil
• some shark livers make up 20% of their weight
• sharks use their pectoral fins and tails for
buoyancy control
Class: Chondrichthyes
Nervous System • lateral line used for sensing vibrations in water
from the swimming of other animals
• system of small canals that run along the head
and body
Class: Chondrichthyes
Nervous System • Ampullae of Lorenzini – jelly filled canals that
can detect electrical and magnetic fields; used
to help locate prey
Class: Chondrichthyes
Nervous System • very acute sense of smell
• It can detect one drop of blood in a million
drops of water (25 gallons) and can smell blood
0.25 mile away.
Class: Chondrichthyes
Reproduction • males have claspers to insert sperm into
female’s cloaca (one opening that serves
digestive and reproductive functions)
MALE
FEMALE
CLOACA
Class: Chondrichthyes
Camouflage and Coloration • some display countershading
• darker on dorsal surface to blend with deeper
water or sea bottom
• lighter on ventral surface to blend with lighter
colored surface water
Class: Chondrichthyes
Clear Nose Skate Atlantic Stingray
• skates are similar to rays but they lack a whip-
like tail and stinging spines
• skates lay egg cases, whereas rays give birth to
live young
Class: Osteichthyes
Types of Bony Fish
1. fleshy-finned fish (ex: coelacanth)
2. ray-finned fish (ex: tuna, marlin, dolphin fish,
lionfish, green moray eel, swordfish,
parrotfish, sailfish, sunfish, grouper)
Class: Osteichthyes
Buoyancy
• have a swim bladder which is an air filled sac
that helps with buoyancy
Class: Osteichthyes
• Atlantic Bluefin
Tuna
• Blue Marlin
• Lionfish
• Parrotfish
• Sailfish
• Sunfish
Additional Information
• Review the material from the “Blue Realm”
video on Manta Rays and Sharks.
• Know the following material from your 8.4 Notes
– 5 different ways fish use coloration
– 3 reasons why fish swim
– nictitating membrane
– 4 main advantages to the lateral line system