Chapter 21

Question 1

Be able to recognize the main characteristics of non-avian reptiles.

Answer 1

-Dry skin covered with scales
-Amniotic eggs w/ a leathery shell
-Ectotherms

Question 2

What does it mean when we say that reptiles are ectotherms?

Answer 2

“Cold-blooded” incapable of maintaining an internal body temperature that is different from the outside

Question 3

What may be the main function of reptilian scales?

Answer 3

Prevent dehydration and protection

Question 4

What is an amniotic egg?

Answer 4

Embryo develops inside the sac in a fluid called amniotic fluid *protection primarily by shock absorption

Question 5

How many species of living sea turtles are there?

Answer 5

Seven living species

Question 6

What is the living sea turtles conservation status?

Answer 6

3 critically endangered
2 endangered
1 vulnerable
1 unknown, not enough data (flatback)

Question 7

What is the carapace and plastron and how does it affect breathing and swimming?

Answer 7

-Carapace and plastron makes up the hydrodynamic shell, the carapace part is dorsal and the plastron part is ventral. The shell is dorsoventrally flattened which makes them better at swimming.
-Since the bones of the carapace and plastron are stiff that meant their chest is rigid/stiff. Since sea turtles have a stiff chest they cannot expand and contract their lung for breathing; so they use muscles in their body (abdominal muscles and leg muscles while they are swimming) to expand and contract their lungs for breathing.

Question 8

Is the carapace covered with scales?

Answer 8

All sea turtles shell are covered by scales except for the leatherback turtles

Question 9

How do sea turtles propel themselves?

Answer 9

Their front legs are modified for propulsion.
Increasing the size of their hand and decreasing size of forearm & upper arm to modify their front legs into better paddles for propulsion

Question 10

How do sea turtles deal with the excess of salt in their diet?

Answer 10

They have salt glands dorsal and medial to their eyes to get rid of excess salt

Question 11

Describe reproduction in sea turtles.

Answer 11

-Mating offshore
-Females leave water only to lay eggs
-Parents do not take care of their offsprings
-Sex of offspring depends on incubation temperature, higher temp = more females (eggs in middle will be warmer)
-offspring emerge primarily at night -> go towards sea (high mortality in offsprings)
(sea turtles return to same location of birth to lay eggs bc of if they survived there their eggs will have a better chance of survival too)

Question 12

Where are seas snakes found?

Answer 12

Indian and Pacific Ocean

Question 13

Why have sea snakes not crossed into the Atlantic Ocean?

Answer 13

Not found crossed into Atlantic ocean or Mediterranean Sea b/c of the Benguela, Peru, and California current which make it cold.

Question 14

How do sea snakes swim?

Answer 14

Swim by undulatory movement -> they throw their body into a wave of increasing amplitude

Question 15

How do sea snakes tails, lungs and salt glands correlate with the environment in which they live?

Answer 15

-Laterally compressed tail (make a paddle) and bodies -> propulsion
-large lung (>80% of body length) -> diving and floatation
* can obtain O2 by diffusion across skin
* one lung is vestigial (reduced in size with little or no function)
-salt glands in floor of mouth around tongue sheath -> get rid of excess salt

Question 16

How do the position of the nostrils, the size of the ventral scales, the reproductive strategy and the amount of time that they typically spend in water vary between sea kraits and true sea snakes?

Answer 16

Sea Kraits
-nostrils lateral (side)
-ventral scales larger -> friction to move through the ground
-oviparous reproduction -> lay egg w yolk sac
-more time on land
Sea Snake
-nostrils dorsal (top) -> breathing at surface & diving
-ventral scales reduced
-aplacentally viviparous -> live brith w yolk sac not placenta
-less time on land

Question 17

What do we mean when we say that the marine iguana is endemic to the Galapagos Islands?

Answer 17

Endemic means one location only, so marine iguanas are only located in the Galapagos island

Question 18

How are the teeth and snouts of marine iguanas correlated with their diet?

Answer 18

They are herbivores
-short snouts -> to get teeth closer to rocks to eat algae
-flat, incisor-like teeth with three cusps -> to scoop & scrape algae off rocks

Question 19

How do marine iguanas animals swim?

Answer 19

Swim by undulatory movement -> tail is laterally compressed for propulsion (wave like pattern)

Question 20

Why are birds included within the class Reptilia?

Answer 20

-Birds closest relative is a group of dinosaurs that are now extinct which is found through fossil evidence.
-Their closest living relative are crocodiles which is fund through molecular evidence (from DNA sequences)

Question 21

What are feathers?

Answer 21

Feathers are modified scales, composed of beta keratin which is what our nails and hair are made of.

Question 22

What was, most likely, the original function of feather?

Answer 22

Thermoregulation -> allowing animal to regulate body temp

Question 23

What other functions do feathers have?

Answer 23

-Advertisement -> colorful feathers attract mate
-Flight -> secondary advantage

Question 24

How can marine birds waterproof their feathers?

Answer 24

Water proof feathers with oil from preen gland.
*pick up oil with beak and spread it throughout the feathers
Oil can also
-prevent the increasing number of parasites between feathers
-maintain good shape of feathers
-water proofing which allows for thermoregulation in the water since the feathers don’t lose most of its surface area

Question 25

List some of the anatomical modifications in birds that improve flight.

Answer 25

-Hollow bones -> less weight (doesn’t lose structural strength of bones)
-Organ reductions (e.g. single ovary, no urinary bladder) -> less weight (vestigial - organ that is small, have little or no function)
-Unidirectional flow of air through lungs -> more efficient gas exchange ( higher in elevation = less O2 available, air only runs in one direction, not two like humans)
-Air sacs -> light weight (also shock absorption during dives / flotation)
-Large keel on sternum for large pectoral flight muscles

Question 26

What do we mean when we say that birds are endotherms?

Answer 26

“Warm-blooded” They have internal sources of heat to regulate their body temperature.

Question 27

How do marine birds get rid of excess salt?

Answer 27

Through salt glands around their eyes -> empty into nostrils (drops out of beak)

Question 28

What is guano?

Answer 28

-Paste-like; contains uric acid (waste from digestive system and kidneys combined into guano)

Question 29

What are some of the advantages of producing guano?

Answer 29

-Really good at conserving water
-Really good fertilizer due to its high content of nitrogen

Question 30

Where are penguins found?

Answer 30

Endemic to Southern Hemisphere (exception the Galapagos)

Question 31

How do the bones and fat content in penguins compare to those in other birds? How is this correlated to their lifestyle?

Answer 31

*Bones are heavier than other birds, which helps with diving (since they are flightless and use their wings are flippers for propulsion)
*They have a layer of fat under the skin, which aids feathers in thermoregulation (since they live in colder environment than regular birds the fat keeps them warm)