16 CLASS CHONDRICHTHYES and CLASS OSTEICHTHYES

Question 1

970 living species; mostly marine with only 28
freshwater species
* Cartilaginous skeleton: Bone is entirely
absent, but phosphatized mineral tissues are
retained in teeth, scales, and spines
* Sharks, skates, rays, chimaeras, and ratfish;
Includes one of the largest living vertebrate
species

Answer 1

Class CHONDRICHTHYES

Question 2

(chondros = “_______” + ichthys = “_____”)

Answer 2

cartilage, fish

Question 3

upper tail fin that is part of the vertebral column; it provides thrust and some lift as it sweeps back and forth

Answer 3

Heterocercal tail / Upper Caudal Tail

Question 4

lower tail fin that is not part of the vertebral column; it is smaller than the
heterocercal tail

Answer 4

Lower Caudal Tail

Question 5

are those that are homologous to limbs of 4-legged chordates:

Answer 5

Major/Appendicular Fins

Question 6

lateral fins; supported by appendicular skeletons and homologous to
forelimbs (arms)

Answer 6

Pectoral fins (paired)

Question 7

fins located on the ventral surface; supported by appendicular skeleton and
homologous to hindlimbs (legs)

Answer 7

Pelvic fins (paired)

Question 8

extensions of the pelvic fins that is used for copulation

Answer 8

Claspers (males only)

Question 9

are more for support and balance in swimming:

Answer 9

Minor Fins

Question 10

usually triangular fin/s on top (dorsal) central line of body

Answer 10

Median Dorsal Fin (one or 2)

Question 11

located at the underside behind the anus

Answer 11

Median Anal Fin (unpaired)

Question 11

for sense of smell (the fact that they are large means they
have excellent sense of smell)

Answer 11

2 large olfactory lobes

Question 12

for sight (excellent vision in water)

Answer 12

2 large optic lobes

Question 13

(hindbrain)

Answer 13

Medulla oblongata

Question 14

located laterally on dorsal side of the head. They are
lidless (there is no need for eyelids to maintain eye moisture when they are already surrounded by water)

Answer 14

eyes

Question 15

electroreceptors located on the ventral side of the head. It is used to hunt prey by detecting their bioelectrical fields in the water.

Answer 15

Ampullae of Lorenzini

Question 16

a horizontal line that runs across the sides of its body (often very visible); it is
composed of special receptors that is used to detect prey from very long distances by sensing their
vibrations in water.

Answer 16

lateral line system

Question 17

Endoskeleton entirely made of

Answer 17

cartilage

Question 18

persists until adulthood, but reduced

Answer 18

notochcord

Question 19

Scales of sharks are called

Answer 19

placoid scales

Question 20

shark (teeth are
continually replaced throughout life)

Answer 20

polyphyodont

Question 21

a common chamber and outlet which the intestinal, urinary, and genital tracts open.

Answer 21

cloaca

Question 21

Respiration by means of 5-7 pairs of gills

Answer 21

the gills are exposed

Question 21

If oviparous, eggs are horny capsules called

Answer 21

mermaid’s purse

Question 22

The 2 dorsal fins look different (the anterior is_____ the posterior is ____ .

Answer 22

spiny, soft

Question 23

(a calcium carbonate structure that is similar to the cochlea in the inner ear of mammals)

Answer 23

otolith

Question 24

unique to bony fishes, it is a large, thin- walled sac lying in the dorsal part of the body cavity.

Answer 24

swim-bladder

Question 25

This is a paired appendicular fin in fishes that is homologous to forelimbs.

Answer 25

pectoral fins

Question 26

This structure allows true fishes to maintain afloat

Answer 26

swim bladder

Question 27

This is a system of sensory cells along the sides of a fish’s body and is used to detect vibrations in the
water.

Answer 27

Lateral-line

Question 28

These are sensory receptors on the head of a shark that detects bioelectrical currents from their prey

Answer 28

Ampullae of Lorenzini

Question 29

This refers to the continuous replacement of teeth throughout the life of a shark.

Answer 29

Polyphyodont