Chapter 3

Question 1

What was the earliest feeding method used by prevertebrates?

Answer 1

Ciliary pumps propelled water past a mucous covered surface

Question 2

What adaptation changed the feeding pattern from that of prevertebrates to that of the agnathans?

Answer 2

The development of a muscularized pharynx AKA a muscular pump, which transported food particles captured by mucous.

Question 3

What adaptation changed allowed gnathostomes to feed differently from their agnathan predecessors?

Answer 3

Jaws

Question 4

What is the inner supporting “weblike” structure behind the lamprey’s head called?

Answer 4

The branchial basket.

Question 5

What is the funnel-like mouth of the lamprey called?

Answer 5

The buccal funnel

Question 6

What are the oral tentacles called in a lamprey’s mouth?

Answer 6

Papillae

Question 7

On a lamprey, the mouth opens into what internal cavity?

Answer 7

The buccal cavity

Question 8

There are a series of round openings running along the side of a lamprey. How many pairs are there, and what are they?

Answer 8

7 pairs, external gill slits

Question 9

Where is the dorsal fin located on a lamprey?

Answer 9

Along the back

Question 10

Where is the caudal fin located on a lamprey?

Answer 10

on the top of the tail

Question 11

What is the circular, spongy part of the lamprey, as seen in cross section?

Answer 11

The notochord.

Question 12

What are the 4 sections of a lamprey heart?

Answer 12

Sinus venosus, atrium, ventricle, conus arteriosus.

Question 13

After the blood leaves the conus arteriosus, it enters what parts of the circulatory system?

Answer 13

The ventral aorta-> the afferent branchial arteries-> the gill capillaries.

Question 14

Blood moves from the gills to the head via what part of the circulatory system?

Answer 14

The carotid artery.

Question 15

What paired veins drain the tail region of the lamprey? How about the head region?

Answer 15

The posterior cardinal veins. The anterior cardinal veins.

Question 16

The left/right anterior cardinal veins fuse with the left/right posterior cardinal veins to form what structure, which in turn enters what part of the circulatory system?

Answer 16

The common cardinal vein, which enters the sinus venosus.

Question 17

What are myomeres?

Answer 17

Blocks of axial musculature.

Question 18

What are myomeres separated by?

Answer 18

Myosepta.

Question 19

What triangular structure is located just above the notochord in a lamprey cross section?

Answer 19

The spinal cord.

Question 20

The caudal artery is directly (dorsally) adjacent to what other part of the lamprey’s circulatory system?

Answer 20

The caudal vein.

Question 21

What part of the lamprey circulatory system is ventrally adjacent to the notochord? (But still dorsal in relation to body plan)

Answer 21

The Dorsal Aorta.

Question 22

What gland, located just behind the nasohhyphyseal opening atop the lamprey’s head, is also called the “third eye”?

Answer 22

The pineal gland.

Question 23

Does the lamprey skeleton have cartilage or bone? (choose one)

Answer 23

Cartilage. There is no bone in the lamprey skeletal system.

Question 24

What is the role of the notochord in the lamprey?

Answer 24

It provides axial support for the body. It keeps the body from “telescoping” due to muscular force.

Question 25

Are lamprey’s monoecious or dioecious?

Answer 25

Dioecious (male and female parts in seperate bodies).

Question 26

The testis/ovary of the lamprey is located where?

Answer 26

Above and behind the liver.

Question 27

What is the role of the pineal gland in lampreys?

Answer 27

Senses light and controls night/day body colour. May also sense light rhythms associated with seasonal activities (ie. metamorphosis and mating)

Question 28

What is the difference between lamprey inner ears and gnathostome inner ears?

Answer 28

Lampreys have paired sets of 2 semicircular canals, whereas all gnathostomes have paired sets of 3.

Question 29

What is the opening atop (dorsal to) the lamprey’s head called? What does it do?

Answer 29

The nasohhyphyseal opening. It pumps water past the nasal duct, allowing for a sense of smell.

Question 30

How does the lamprey larva feed?

Answer 30

By pumping water through the pharynx via the muscular velum.

Question 31

Name the 3 parts of the larval lamprey brain, in order anterior to ventral.

Answer 31

1) Prosencephalon
2) mesencephalon
3) rhombencephalon

Question 32

What are the 2 parts of the pharyngeal gills, as labelled on the lamprey larvae diagram (p.28)

Answer 32

Gill slits and gill filaments.

Question 33

Beside serving feeding, the new muscular pump also helped with what?

Answer 33

helped push water across the newly evolving gills therby supporting the increased respiratory demands in this active prechordate

Question 34

what are the only two living agnathans?

Answer 34

lamprey and hagfish

Question 35

dorsally between the eyes on the top of the head lies a single median ———– ——–

Answer 35

nasohypopyseal opening

Question 36

how does water exit?

Answer 36

through the external pharyngeal slits

Question 37

The liver gonad and intestine reside within what cavity?

Answer 37

pleuroperitoneal cavity

Question 38

the lamprey heart resides in what portion of the coelom?

Answer 38

pericardial cavity

Question 39

what vein drains the cranial end of the body into the sinus venosus?

Answer 39

inferior jugular vein, runs along the ventral edge of the body

Question 40

myomeres arose from what?

Answer 40

myotomes

Question 41

the nerves of lampreys are unique in 2 ways:

Answer 41

1. the dorsal and ventral roots of the spinal nerves do not join lateral to the spinal cord
2. all of the nerves are unmyelinated

Question 42

food particles capturedin the mucus follow what route through the lamprey?

Answer 42

pass down the pharynx into the esophagus then the instestine and finally out of the anus located near the base of the tail