Anatomy and physiology of amphibians, chelonians & snakes

Question 1

Reptiles are divided into what 4 different orders

Answer 1

Crocodilia (crocodiles, gavials, caimans, and alligators)

Sphenodontia (tuataras from New Zealand)

Squamata (lizards, snakes, and worm lizards

Testudines (turtles and tortoises)

Question 2

Chelonians are

Answer 2

a reptile of the order Testudines (formerly Chelonia ); a turtle, terrapin, or tortoise.

Chelonians live the longest, with many living well over 50 years in captivity.

Various classifications,
Tortoises - land based
Turtles - marine and aquatic species
Terrapins - freshwater semi-aquatic

Question 3

Describe Chelonian body temperature.

Answer 3

Chelonians are heliotherms with a temperature range from 22 to 33º C.

Many smaller species bask in the sun to heat up.

They have difficulty cooling down, owing to their shell, so seek shade by
burrowing under vegetation.

Can also lose heat by evaporative cooling: hypersalivating or urinating on their legs and plastron (belly).

Question 4

Describe chelonian hibernation.

Answer 4

Chelonians from subtropical or temperate areas hibernate in winter months under the influence of decreasing temperatures.

Terrestrial species bury themselves below the frostline underground while some aquatic species bury themselves in mud at the bottom of a pond where water is so dense it does not freeze.

Question 5

The dome of the shell is called

Answer 5

the carapace and the flat underpart is
called the plastron.

Joint between the carapace and plastron: the bridge.

Question 6

Describe the chelonian spine.

Answer 6

There are 18 presacral vertebrae, consisting of 8 cervical and 10 trunk vertebrae. The trunk vertebrae each have rib attachments which fuse with the dermal bone plates.

The cervical and caudal vertebrae are free and flexible.

Neck and tail are flexible but rest of spine is fused with shell, rib cage, and plastron

Question 7

The chelonian scapula fuses dorsally with the

Answer 7

carapace and ventrally articulates
with the humerus. The humerus and femur are short in length.

The pectoral and pelvic bony girdles are attached to the plastron and carapace by fan-shaped pectoral and pelvic muscles.

Question 8

The outer part of the chelonian’s hell is covered with

Answer 8

horny scutes formed from the epidermis.
The scutes are innervated and bleed if damaged.

New growth in the shell can be interrupted by changes in food supply, seasonal change, and hibernation.

Chelonians shed their skin but in a pieces.
Aquatic terrapins (turtles) shed their scutes as they grow.

Question 9

Chelonian heart is

Answer 9

three chambered with an incomplete ventricular septum.

Venous drainage from the pelvic limb drains into the kidney to form the renal portal system. Thus, all meds must be administered in the cranial half of the body!

Question 10

Some chelonian species have a lymphatic ring around

Answer 10

the base of the neck.

Question 11

The chelonians can easily switch to the dive reflex and thus employ

Answer 11

anaerobic respiration.

Question 12

Describe the chelonian Respiratory system.

Answer 12

Lungs are not surrounded by a pleural cavity. Lungs are only separated from the ventral cavity and viscera by a thin non-muscular post-pulmonary septum.

They do not have a diaphragm.

In order to breathe, chelonians have developed strong trunk muscles. When the muscles expand and contract, the chelonian breathes via active inspiration and expiration.

In aquatic species, respiration is aided by the hydrostatic pressure of water.

Some semi-aquatic freshwater turtles possess the ability to absorb oxygen via well vascularized cloacal bursae.

Question 13

Are all chelonians herbivoirous?

Answer 13

About 25% of Chelonia are herbivorous, the rest are many omnivores.

Chelonians have no teeth so are unable to chew.

The liver is large and divided into two lobes.

A cecum may be present but it is not well developed.

Digestive enzymes are produced by the stomach, small intestine, pancreas,
liver, and gall bladder.

Passage of food is slow and can take up to two to four weeks.

Question 14

The chelonian kidneys are

Answer 14

large, flat, lobulated organs lying under the caudal carapace.

Chelonians have urinary bladder.

Question 15

chelonian urogenital system

Answer 15

All chelonians are oviparous.

In females the genital ducts are quite close to the bladder - this means that eggs can even make their way into the bladder! (fo real)

Testes are attached to the cranioventral pole of the kidneys.

Question 16

Determining the sex of a chelonian

Answer 16

The tail is often longer and thicker in the male.
Male aquatic species have longer claws on the forelimb. These 2 methods of identification are most common.

In land tortoises: the male plastron is concave while the female’s is flat or convex.

More pronounced in species with high domed shells.

The vent in the male is situated beyond the outer margin of the carapace.

Question 17

Chelonians have no nasolacrimal ducts and so lose tears by

Answer 17

evaporation.

Question 18

Hearing in chelonians is

Answer 18

poor.

There is no external ear but an inconspicuous tympanic membrane covered in skin.

Question 19

Snakes evolved from

Answer 19

lizards, which have a short trunk and long tail.

During this process snakes developed the converse of this and have a long trunk with a short tail.

Question 20

Do snakes hibernate?

Answer 20

In temperate climates snakes hibernate during the cold months.

Question 21

Snakes like pythons and boas can live for as long as

Answer 21

20–30 years and colubrids live for
about 20 year.

Question 22

The cross-section of snakes can vary from

Answer 22

circular to triangular to ovoid.

The belly is always slightly flattened to aid locomotion.

Question 23

Elongation in snakes has resulted in asymmetry of viscera with right-sided organs lying

Answer 23

cranial to and being larger than left.

Question 24

Snake bodies are usually divided into three regions:

Answer 24

The cranial region has the heart, trachea, esophagus, thyroid and proximal lung.

The middle region has the stomach, liver, other lung if present, spleen, and pancreas.

The caudal region has the small and large intestines, kidneys and gonads.

Question 25

The snake heart lies

Answer 25

cranioventral to the termination of the trachea.

It is mobile to allow for the passage of large food items.

Question 26

In some snake species, the spleen and pancreas are

Answer 26

fused into a splenopancreas and lie adjacent to the gall bladder.

Question 27

Snake right and left gonads occur in sequence, followed by

Answer 27

the right and left kidneys.

Question 28

Snakes have celomic fat bodies. What does this mean?

Answer 28

Celomic fat bodies in snakes refer to specialized structures found in their coelom, which is the body cavity containing their internal organs.

Having celomic fat bodies allows snakes to survive in environments where food availability fluctuates or during periods of prolonged fasting, such as during hibernation or aestivation (dormancy).

These fat reserves provide them with energy to sustain vital physiological functions until they can find their next meal.

Question 29

Describe the snake Skeletal system

Answer 29

The braincase is heavily ossified. But Snakes have the most kinetic skull with extremely flexible and mobile bones in all parts.

Snakes have no mandibular symphysis.

There are often up to 400 vertebrae. Snakes have no distinct cervical region but the first two cervical vertebrae lack ribs.

There are no sternum or costal cartilages.
Post cloaca there are no distinct ribs.

Some snakes have retained pelvic
vestiges, “spurs” on either side of the
vent.

Question 30

Snake shedding frequency is affected by many factors: (3)

Answer 30

Growth
Season
Oviposition or parturition

Question 31

Describe the snake Cardiovascular system

Answer 31

Snakes have a 3-chambered heart with a
complete atrial separation and just one
ventricle.

Lymphatic vessels are prominent.

Snakes have a large ventral abdominal vein
that lies along the inner surface of the
midline.

Snakes have a renal portal system.

Question 32

describe what you see

Answer 32

The snake’s glottis lies forward and is easily visualized.

Snakes have no vocal cords but hiss by forcing air through the glottis.

Question 33

Snakes have a poorly developed mucociliary apparatus and thus rely on

Answer 33

body positioning to help clear mucus and inflammatory exudates.

Question 34

Snake respiratory system

Answer 34

Snakes have no diaphragm.

Snake lungs show a remarkable diversity of organ asymmetries. The right lung is always fully developed, while the left lung is either absent, vestigial, or well-developed (but smaller than the right). A ‘tracheal lung’ is present in some taxa.

Respiration is controlled by the dorsal and ventrolateral sheet of intercostal muscles.

Question 35

Venom glands are

Answer 35

modified labial salivary glands, that produce venom that immobilize the prey preventing damage to the delicate skull.

Question 36

The tongue is long, slender and forked and can be protruded through the

Answer 36

lingual notch or fossa.

Question 37

The snake esophagus is

Answer 37

relatively thin walled and amuscular.

The stomach is fusiform and there is no well-defined cardiac sphincter.

Question 38

The snake liver is

Answer 38

elongated and may be divided into two to
three separate lobes.

Question 39

Do snakes have a cecum?

Answer 39

The small intestine is fairly straight and a cecum is present is some species.

Question 40

Snake Urogenital system

Answer 40

The paired kidneys are located in the dorsocaudal abdomen and have about 25–30 lobes.

Snake have no urinary bladder. Snakes have a cloaca and vent.

Question 41

Snake reproductive system.

Answer 41

In males the testes are intra-abdominal and situated between the pancreas and the kidneys.

Male snakes have two paired hemipene.

In females the paired ovaries are located
asymmetrically near the pancreas.

Snakes can be oviparous or viviparous.
Oviparous animals are the ones who lay eggs. Viviparous animals are the ones that give live birth.

Question 42

Describe snake senses.

Answer 42

Sight is quite poor in snakes.

The eyes have no eyelids but have fused to form a protective spectacle.

Snakes have no tympanic membrane, and only a narrow tympanic cavity.

Snakes are not deaf but hearing sensitivity is only over a limited low frequency in the range of 150–600 Hz.

Olfaction is the most developed of senses in snakes due to the Jackobson’s organ.

Some snakes possess specialized infrared receptors.

Question 43

If you need to remove part of a chelonians plastron and reattach it after (e.g. screws or glue) - how long will it take to heal?

Answer 43

a couple years

Question 44

identify species

Answer 44

leopard tortoise