Chapter 19 Flashcards
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
How do sharks breathe?
Either through ram ventilation or pumping using mouth / spiracles
What is ram ventilation?
Swimming with mouth open, water comes in, water comes out through gills where gas exchange happens for breathing.
What is unique about the jaws and teeth of sharks?
-Jaws are partially calcified (when skeleton of shark is made of cartilage) with several rows of deciduous (continuously replace teeth throughout their life) teeth
-upper jaws are not fused to the cranium which allows for it to protrude from its cranium
How do sharks achieve a greater surface area for nutrient absorption and digestion in their
intestine?
With the spiral valve
What is the spiral valve?
Like a spiral staircase in the intestine of the shark to increase surface area for nutrient absorption (since sharks have a small intestine and do not chew their food)
Describe the ampullae of Lorenzini: general structure and functions
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
How are the bodies of rays and skates different from those in sharks?
The bodies of rays and skates are dorsoventrally flattened (a flat shark)
- gill slits, external nares, and mouth are ventral(bottom)
-eyes and spiracles are dorsal(top)
How are the claspers of chimaeras different from those of sharks, rays and skates
Males with a copulatory organ on their head (Cephalic clasper)
*used only to hold onto the female NOT to transfer sperm
