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BI1512 - Diversity of Life 2 > Reptiles > Flashcards

Reptiles Flashcards

1
Q

When did the reptiles arise?

A

Palaeozoic era during the Carboniferous period (310 - 320 MYA)

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2
Q

What is the first-known reptile called?

A

Hylonomus

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3
Q

Reptiles are classified in ____ orders.
___ orders are extinct.
___ orders remain - ~10000 species

A

(1) 16
(2) 12
(4)

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4
Q

What are the 4 remaining orders?

A
  • Rhynchocephalia (1 species)
  • Chelonia (341 species)
  • Crocodilia (25 species)
  • Squamata (9,671 species) ; Amphisbaenia (188 species); Sauria (lizard - 5,987 species); Serpentes (snake - 3,496 species)
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5
Q

The importance of skull fenestration. What type of animals have:

One skull opening (lateral temporal opening)?

Two openings (dorsal and lateral temporal openings)?

No opening?

A

(1) Mammals
(2) Reptiles and Birds
(3) Amphibians & Reptile-like amphibians

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6
Q

What is meant by CLADISTIC CLASSIFICATION?

A

(based on common ancestry)

  • Splits the diapsids into three major lineages:
    Lepidosauria (Tuatara, modern snakes & lizards)
    Archosauria (extinct dinosaur lineages, crocodilians & birds)
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7
Q

______ have lost their skull fenestration and now have an _______ skull.

A

(1) Chelonians

(2) anapsid

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8
Q

Name at least 3 differences between reptiles and amphibians.

Briefly describe

A
  • Reptilian skin is dry and scaly, limits water loss; Stratum corneum (dead cells) are permanent in reptiles resulting in moulting; Beta-keratin is more rigid
  • Amniotic egg: allows embryo to bypass the aquatic stage of amphibians; AMNION: fluid-filled sac that surrounds and cushions the developing embryo. CHORION: outermost layers, allowing gas exchange. ALLANTOIS: excreted wastes from embryo. YOLK SAC: nutrient-rich food supply for the embryo
  • Reptilian jaws are more powerful; the openings in the skull (fenestration) provide additional surface area for MUSCLE ATTACHMENT allowing greater pressure to be exerted. With the exception of TURTLES, which have a horny beak (sometimes serrated), all reptiles possess TEETH and many of them have them on both the palate and the jaw.
  • Most reptiles have HOMODONT detinition: PARTIAL HETERODONTY occurs in snakes (i.e. fang) and a few lizards
  • Orientation of limbs: In most reptiles, the appendages are ROTATED TOWARDS THE BODY; the long axis of the limbs lie MORE PARALLEL to the body’s main axis; the angle between the upper and lower limbs is reduced; LIMBS ARE STRAIGHTER –> provides BETTER SUPPORT FOR THE WEIGHT OF THE BODY and make GREATER AGILITY and SPEED possible
  • Reptiles have INTERNAL FERTILISATION and so, males have a COPULATORY ORGAN
  • Reptiles REPRODUCTIVE LIFE HISTORIES; most species are OVIPAROUS
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9
Q

Briefly describe the amniotic egg.

A
  • Calcium-impregnated shell that prevents the evaporation of fluids inside but allows gas exchanges
  • Large quantities of yolk –> allows embryo to attain a relatively advanced state of development before it hatches; NO METAMORPHOSIS
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10
Q

Briefly describe the characteristics seen in the three different amniote reproductive strategies.

A

OVIPAROUS: Shell present; Embryo grows OUTSIDE the shell; Food comes from the EGG; Seen in Birds, Reptiles, Few Mammals

OVOVIVIPAROUS: Shell present; embryo growth INSIDE the shell; Food comes from the EGG; Seen in REPTILES

VIVIPAROUS: No shell; embryo grows INSIDE mother; Food comes from the MOTHER; Seen in MAMMALS, few Reptiles

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11
Q

Briefly describe the viviparous squamous cells

A

Exhibit placentae formed by the appositions of maternal and embryonic tissues

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12
Q

What is parthenogenesis?

A

TRUE parthenogenesis is the complete absence of male contributions - NO SEXUAL REPRODUCTION

Only 0.1% of all vertebrate species do this - it is VERY RARE

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13
Q

Show the different sexual chromosomes seen. Distinguish which are male and which are female

A

XY/XX (Male/Female): seen in most reptiles with sexual chromosomes & mammals

WZ/WW (Male/Female) : Few reptiles & birds

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14
Q

Are all offspring that are created through parthenogenesis female?

A

NO

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15
Q

Briefly describe temperature dependant sex determination

A
  • Temperature of nest affects rate of embryonic development
  • Excessive high/low temperatures can be lethal
  • Sex determination by temperature of developing eggs is wide spread in turtles, all crocodilians and many lizards; In turtles HIGH temperatures result in LARGER individuals which are usually FEMALE; In some lizards this is the opposite, High temperature = males
  • Viviparous lizard selects sex of embryos; Influence of gestation temperature on the sex ration; Mothers can choose the sex of offspring via basking behaviour.
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16
Q

Briefly describe respiration in reptiles

A
  • Although reptilian respiration primarily depends on lungs, some gas exchange takes place across the inside of the mouth and in the cloaca particularly in various turtles
  • Soft-shelled turtles, up to 70% of gas exchange may take place across the leathery skin that covers the shell
  • NEGATIVE PRESSURE BREATHING
  • Most reptiles breathe by expanding and compressing the body cavity by movements of the ribs produced by contracting the intercostal muscles
  • NO DIAPHRAGM
17
Q

Briefly describe the effects of lateral undulations of walking/running lizards

A
  • As lateral movements to the left, left lung is compressed
  • As lateral movements to right, right lung is compressed
  • As animal runs, air is pumped between lungs, but little in and out through the trachea
  • Lizards that retain this methods of breathing can only run for 1-2 minutes
18
Q

Briefly describe respiration in snakes

A
  • Single (dominant, left) lung in snakes
  • NO DIAPHRAGM, ribs provide movement
  • ANTERIOR PART NON-RESPIRATORY –> functions as air sac (gas exchange)
  • GLOTTI: help respiration when ingesting large preys
19
Q

Briefly describe respiration in turtles

A
  • Lungs lie within a protective rigid shell
  • Fixed rib cage cannot act to ventilate lungs
  • They have specialised sheets of muscle within shell that contract and relax the lungs
  • Air pressure in lungs can be changed by moving limbs in and out
20
Q

In terms of respiration, what is meant by Bidirectional flow?

A
  • Air moves tidally in to and out of terminal gas-exchange structures, which are cul-de-sacs (amphibians, mammals, most reptiles)
21
Q

In terms of respiration, what is meant by Unidirectional flow?

A
  • Air in only one direction during both inspiration and expiration (birds, some alligators, some reptiles)
22
Q

Briefly describe the pulmonary circuit

A

Reptiles: efficient pulmonary circulation to bring blood to and from the lungs

  • Developed a septum that partially divides the ventricle into separate left and right chambers (3-CHAMBERED HEART)
  • In Crocodilians (and birds) the separation of the ventricles is complete (4-Chambered heart)
  • This greatly reduces the mixing of oxygenated and deoxygenated blood
23
Q

Briefly describe excretion

A
  • The method of NITROGEN EXCRETION depends on the habitat; Aquatic reptiles (i.e. turtles) –> ammonia (possibly urea) as amphibians; Terrestrial reptiles (i.e. lizards, snakes & tortoise) –> uric acid
    Urea: helps to conserve water - excreted from the cloaca
  • Kidneys: no loops of Henle –> unable to produce concentrated urine
  • Bladder: present in chelonians (turtles): absent in snakes and some lizards
24
Q

Briefly describe the nervous system and sensory function in reptiles

A
  • Increased brain size in reptiles, when compared to amphibians –> especially the CEREBRUM and CEREBELLUM
  • But brain size still small when compared to birds and mammals
  • Reptile bigger brain –> motor skills & hunting strategies (sensory development)

Vision:
Reptiles active in the day: Complex eyes (rods and oil droplets); see colour well
Reptiles active at night: Lizards –> large pupillary and lens aperture; Snakes –> infrared “vision”

Smell:
All reptiles have a VOMERONASAL organ (or Jacobson’s organ) inside the mouth on the palate to detect chemicals via the tongue (found in all vertebrates, but only enhanced in a few)
Some snakes (Vipers, Pythons & Boas) have a pit organ for infrared “vision”

Hearing:
Some reptiles have an external ear structure –> visible tympanic membrane; Airborne vibrations go to the tympanic membrane; Substrate (ground) –> quadrate
Reptiles quadrate forms part of the jaw joint

25
Q

Briefly describe the Jacobson’s Organ

A
  • Smell rerouted from the nose to the tongue
  • Tongue extension: Odour particles are captured from the air by the tongue; Odour particles are delivered by the tongue to the openings of the VOMERONASAL organ
  • The degree of the fork indicated the use of the organ
26
Q

Briefly describe the Pit Organ

A
  • Molecular basis of infrared detection by snakes
  • Pit organ –> detection (“smell”) of infrared radiation (>0.001’C)
  • Transient receptor potential (TRP) channels (TRAP1) –> thermosensors in the vertebrate nervous system
27
Q

Briefly describe thermoregulation

A

Modern reptiles are ECTOTHERMS

  • Different adaptations to regulate body temperature:
  • Morphology: Skin colouration; crest…
  • Behaviour: Basking
  • Physiology: Heart rates
28
Q

Briefly describe Rhynchocepalia

A

1 Species: TUATARA

  • Found on a few islands in New Zealand
  • Adult tuatara up to 80cm and 1.3kg
  • Only surviving members of their order, which flourished around 200 million years ago
  • No external ears, primitive scales, mode of locomotion and heart closer to amphibians
  • “third eye” (PARIETAL EYE) –> lens, cornea & retina but degenerated nervous connection to the brain
  • Not used for vision (may regulate day-night cycles or absorb UV to obtain Vitamin D)
29
Q

Briefly describe Chelonia

A
  • Turtles & Tortoises
  • 3% of reptiles species
  • 341 species
  • 14 families
  • The monophyly of turtles has never been questioned
  • Two part-shell built in the skeleton ; Dorsal part - CARAPACE; Ventral part - PLASTRON
  • Skull: no fenestration
  • Beak instead of teeth (omnivorous)
  • Different habitat: Marine; Freshwater; Terrestrial
30
Q

Briefly describe Crocodilia

A
  • Crocodiles, alligators, caimans & gharials
  • > 1% of reptile species
  • 25 species
  • 4 families
  • Modern crocodiles and birds are the only survivors of the Archosaurian lineage
  • Have changed little in almost 200 million years… living fossils
  • 4 chambered heart
  • Unidirectional respiration found in alligators
  • Diapsid skull - powerful jaw, on close, not open
31
Q

Briefly describe Squamata

A
  • Lizards, snakes, worm lizards
  • 9,671 species
  • 96%
  • 3 sub-orders: Amphisbaenia; Sauria; Serpents
32
Q

Briefly describe the sub-order Amphisbaenia

A
  • Worm-like lizards
  • Exclusively legless (apart from 4 species in one genus that retain forelimbs)
  • Tunnelling lizards –> variety of specialised adaptations for digging and moving in burrows
  • Head heavily keratinised
  • Skin distinctive & rings (annuli) encircle body
  • Widely distributed (America, Europe, Africa)
33
Q

Briefly describe the sub-order Sauria

A
  • Lizards
  • Large variation in size and body form
  • Infraorder: Iguania (14 families)
  • Infraorder: Gekkota (7 families)
  • Infraorder: Scincomorpha (7 families)
  • Infraorder: Platynota (Varanoidea) (3 families)
  • Most lizards are nonvenomous: But best known is Gila monster –> long though of as being the only venomous lizard; recent evidence pointing to new species
34
Q

Briefly describe the sub-order serpentes

A
  • Snakes
  • Can be distinguished from legless lizards by their lack of eyelids and external ears.
  • COLUBROIDEA: includes most of the living species of snakes; the family along contain 2/3 of all snakes
  • Many Colubrid snakes are VENOMOUS
  • Elapids and Viperids possess hollow FANGS at the front of the mouth and have highly toxic venom
35
Q

What is meant by Aglyphous?

A

A snake without fangs

36
Q

What is meant by Opisthoglyphous?

A

A snake with fangs at the rear of the maxilla

37
Q

What is meant by Solenoglyphous?

A

A snake with fangs on a rotating maxilla

38
Q

What is meant by Proteroglyphous?

A

A snake with permanently erect fangs at the front of the maxilla

BI1512 - Diversity of Life 2 (14 decks)

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