Chapter 19
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Recognize some of the animals that are included in the group Chondrichthyes?
Sharks, rays, skates, and chimaera
What is the name Chondrichthyes referring to?
Cartilage fishes
Describe the differences between bone and cartilage, advantages and disadvantages
*Cartilage is light weight and flexible *Bone is hard and not flexible *advantage of cartilage -> light weight and flexible *disadvantage of having cartilage instead of bone -> bone heals faster due to better blood supply, and provides protection and structural support; which cartilage does not
What are placoid scales?
Tooth like organs on the skin of the fish
What are they like structurally and what are their functions?
They are structurally like teeth, their function is protection and easier to swim through water
How can you sex these animals?
By seeing if the animal has a clasper or not; females don’t have claspers while males do
What are claspers?
Copulatory organs: responsible of delivery sperm to the female
The three reproductive strategies found in Chondrichthyes.
*Oviparity *Viviparity *Aplacental Viviparty
oviparity
Release egg into environment; embryo receives nourishment via yolk sac
aplacental viviparity
Embryos kept inside mother’s uteri (two); embryo receives nourishment via yolk sac
viviparity
Embryos kept inside mother’s uteri (two); embryo receives nourishment via placenta-like organ
What is a fusiform body?
Torpedo shaped body, most efficient for swimming.
Name the external anatomy of the shark.
pectoral fins, pelvic fins, dorsal fins, anal fin, caudal fin, claspers, spiracles, gills slits, external nares, lateral line, ampullae of Lorenzini.
pectoral fins
Ventral pair of fins used for lift and maneuverability
Pelvic fins
Ventral pair of fins used for balance.
Dorsal fins
Dorsal (top) fins used for balance.
Anal fin
Fin behind the anus used for balance (in some sharks)
Caudal fin
Fin located in tail region used for propulsion and lift
Claspers
Only on male on pelvic fins used for grabbing female and transferring sperm
Spiracles
Above the eye area used to bring water in, to go by gills for gas exchange.
Gill slits
Water leaves the body through the gill slits while it passes out gas is exchanged.
External nares
Nostrils on the nose used for smell NOT BREATHING
Lateral line
A sensory system to detect vibrations in water.
Ampullae of lorenzini
Canals and conduction gel -uses Electroreception (detect electrical fields) -> allows to detect prey Orientation relative to magnetic field of earth -> navigate Location of the prey