Chapter 19

Question 1

Recognize some of the animals that are included in the group Chondrichthyes?

Answer 1

Sharks, rays, skates, and chimaera

Question 2

What is the name Chondrichthyes referring to?

Answer 2

Cartilage fishes

Question 3

Describe the differences between bone and cartilage, advantages and disadvantages

Answer 3

*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

Question 4

What are placoid scales?

Answer 4

Tooth like organs on the skin of the fish

Question 5

What are they like structurally and what are their functions?

Answer 5

They are structurally like teeth, their function is protection and easier to swim through water

Question 6

How can you sex these animals?

Answer 6

By seeing if the animal has a clasper or not; females don’t have claspers while males do

Question 7

What are claspers?

Answer 7

Copulatory organs: responsible of delivery sperm to the female

Question 8

The three reproductive strategies found in Chondrichthyes.

Answer 8

*Oviparity
*Viviparity
*Aplacental Viviparty

Question 9

oviparity

Answer 9

Release egg into environment; embryo receives nourishment via yolk sac

Question 10

aplacental viviparity

Answer 10

Embryos kept inside mother’s uteri (two); embryo receives nourishment via yolk sac

Question 11

viviparity

Answer 11

Embryos kept inside mother’s uteri (two); embryo receives nourishment via placenta-like organ

Question 12

What is a fusiform body?

Answer 12

Torpedo shaped body, most efficient for swimming.

Question 13

Name the external anatomy of the shark.

Answer 13

pectoral fins, pelvic fins, dorsal fins, anal fin, caudal fin, claspers, spiracles, gills slits, external nares, lateral line, ampullae of Lorenzini.

Question 14

pectoral fins

Answer 14

Ventral pair of fins used for lift and maneuverability

Question 15

Pelvic fins

Answer 15

Ventral pair of fins used for balance.

Question 16

Dorsal fins

Answer 16

Dorsal (top) fins used for balance.

Question 17

Anal fin

Answer 17

Fin behind the anus used for balance (in some sharks)

Question 18

Caudal fin

Answer 18

Fin located in tail region used for propulsion and lift

Question 19

Claspers

Answer 19

Only on male on pelvic fins used for grabbing female and transferring sperm

Question 20

Spiracles

Answer 20

Above the eye area used to bring water in, to go by gills for gas exchange.

Question 21

Gill slits

Answer 21

Water leaves the body through the gill slits while it passes out gas is exchanged.

Question 22

External nares

Answer 22

Nostrils on the nose used for smell NOT BREATHING

Question 23

Lateral line

Answer 23

A sensory system to detect vibrations in water.

Question 24

Ampullae of lorenzini

Answer 24

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

Question 25

How do sharks breathe?

Answer 25

Either through ram ventilation or pumping using mouth / spiracles

Question 26

What is ram ventilation?

Answer 26

Swimming with mouth open, water comes in, water comes out through gills where gas exchange happens for breathing.

Question 27

What is unique about the jaws and teeth of sharks?

Answer 27

-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

Question 28

How do sharks achieve a greater surface area for nutrient absorption and digestion in their intestine?

Answer 28

With the spiral valve

Question 29

What is the spiral valve?

Answer 29

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)

Question 30

Describe the ampullae of Lorenzini: general structure and functions

Answer 30

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

Question 31

How are the bodies of rays and skates different from those in sharks?

Answer 31

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)

Question 32

How are the claspers of chimaeras different from those of sharks, rays and skates

Answer 32

Males with a copulatory organ on their head (Cephalic clasper) *used only to hold onto the female NOT to transfer sperm