Sharks

Question 1

What class do sharks belong to?

Answer 1

Chondrichthyes

Question 2

How many species?

Answer 2

~350-370

Question 3

4 points about reproduction in sharks

Answer 3

Internal fertilization, Long gestation period, Long maturation period, Produces small numbers of relatively large young

Question 4

What type of tail does a shark have?

Answer 4

Heterocercal

Question 5

What type of “scales” does a shark have?

Answer 5

Dermal denticles (placoid). A tough, protective covering on skin that resemble tiny teeth. Have hydrodynamic properties that allow sharks to move with minimal water resistance.

Question 6

How do dermal denticles feel?

Answer 6

Nose to tail, smooth. Tail to nose, rough.

Question 7

Nares

Answer 7

External nostrils.

A nasal flap separates the incurrent from the excurrent opening. Water passes into and out of the olfactory sac, permitting the shark to detect the odors of the water.

Question 8

Ampullae of Lorenzini

Answer 8

The patches of pores (dark in color) on the head in the areas of the eyes, snout, and nostrils.

Specialized sensory cells that are capable of detecting weak electric fields at short ranges, enabling sharks to locate prey without visual or olfactory cues.

Question 9

Spriacle

Answer 9

Located posterior to the eye.

A rudimentary first gill slit, highly reduced/absent in most fast-moving sharks. Provides for oxygenated blood directly to the eye and brain via a separate blood vesel.

Question 10

Gill slits

Answer 10

Located on sides, behind the mouth and before the pectoral fin.

Exit for water that has bassed through the gills. Water taken in by the mouth and spiracles is passed over the internal gills and forced out by way of the gill slits.

Question 11

Claspers

Answer 11

Male copulatory organs.

Located on inner side of pelvic fins, on posterior end of fin.

Question 12

Lateral line

Answer 12

Along the sides of the body, a series of small fluid-filled canals lying just beneath the skin on the head and along the sides of the body. Light colored line.

This complex system of receptors transforms underwater sound or mechanical disturbance (or change in water pressure) into nerve impulses that allows a shark to orient to the source.

Question 13

First dorsal fin

Answer 13

First fin located on the dorsal (top) side of the shark. Can be preceded by the fin spine.

Question 14

Interdorsal ridge

Answer 14

Space along the dorsal side of the shark between the first and second dorsal fins.

Question 15

Second dorsal fin

Answer 15

Second fin located on the dorsal side of the shark.

Question 16

Caudal fin

Answer 16

Tail fin. Divided into upper lobe, terminal lobe, lower lobe (heterocercal)

Question 17

Caudal peduncle

Answer 17

Space on the body after the second dorsal fin & anal fin, and before the caudal fin

Question 18

Pectoral fin

Answer 18

Located on sides of the body, act like airplane wings to provide lift/prevent sinking

Question 19

Anal fin

Answer 19

Located on the ventral (underside) side of the shark, opposite to the second dorsal fin.

Question 20

Pelvic fin

Answer 20

Located on the ventral (under) side of the shark, before the anal fin. This is where the claspers are located in males.

Question 21

Cloaca

Answer 21

Located on the ventral side between the pelvic fins. (Right before pelvic fins in side view)

“Common exit” for waste products (urinary, intestinal, genital)

Question 22

Stomach

Answer 22

Centrally located in the main body cavity, goes almost entire length of cavity. Three parts: cranial, fundic and pyloric.

Function: food storage and digestion

Question 23

Pancreas

Answer 23

Located in the middle of the body cavity, underneath the middle of the stomach

A flattened white gland that secretes digestive juices and insulin.

Question 24

Gall bladder

Answer 24

Green sac that holds bile for enzymatic digestion

Question 25

Intestine

Answer 25

End of stomach. Contains the spiral valve, which is an internally coiled organ that serves to increase the absorptive surface of the intestine.

Question 26

Liver

Answer 26

Large, soft, oily organ that occupies as much as 25% of the body cavity. Aids in buoyancy.

Function: bile secretion, glycogen and Vitamin D storage

Question 27

Spleen

Answer 27

Triangle shaped, located toward back of body cavity (upper right corner)

Maintenance of blood (destroys old RBCs and makes new RBCs)

Question 28

Heart

Answer 28

Muscular S-shaped tube with 2 chambers for pumping blood throughout the body

Question 29

Ventricle

Answer 29

pumping chamber of the heart

Question 30

Atrium

Answer 30

collecting point of blood for all veins

Question 31

Gill Lamellae

Answer 31

feather-like portion of the gills responsible for gas exchange

Question 32

Kidneys

Answer 32

Located at top of body cavity; long, skinny, tube-like structure

Function: elimination of waste and regulation of internal environment

Question 33

Rectal gland

Answer 33

Small, leaf-shaped organ at back end of the body cavity

Function: acts as a salt gland for osmoregulation by removing excess sodium chloride from the blood and excreting it through a duct in the rectum

Question 34

Ovaries/Testes

Answer 34

Female: egg and hormone production
Male: gonads for sperm production