Reptiles
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Reptiles. Diversity. Diversity Found on every continent but Antarctica Mainly found in tropics and subtropics Produce some heat Do not generate enough to maintain constant body temp (still ectothermal /cold-blooded) Good for reptiles—don’t have to eat to maintain body temp. Diversity.

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Diversity
Diversity

  • Diversity

    • Found on every continent but Antarctica

    • Mainly found in tropics and subtropics

    • Produce some heat

      • Do not generate enough to maintain constant body temp (still ectothermal/cold-blooded)

      • Good for reptiles—don’t have to eat to maintain body temp


Diversity1
Diversity

  • Diversity

    • Reptiles included amniotes – those animals who produce a shelled, amniotic egg

      • Do NOT INCLUDE birds and mammals

    • Examples include:

      • Crocodiles, alligators, lizards, snakes, and turtles, Komodo dragon

    • Grouped together as the class Reptilia

      • Latin repere means "to creep"


General Characteristics

  • Reptiles are tetrapods

    • Vertebrates with four legs

  • Contain tough keratinized skin

    • Provides protection against injury

    • Scales or bony plates (well-developed dermal layer)

    • Contain chromatophores

  • Excretory system

    • Two small kidneys.

    • Uric acid is the main waste product.


General Characteristics

  • Contain powerful jaws

    • Desgined for applying crushing or gripping force

    • Used to kill/capture prey

    • FYI: Fish/Amphibian jaws designed for quick closure (with little pressure/force)

    • Reptile muscles (in jaw) are larger, longer and arranged to apply a strong grip


General Characteristics

  • Circulatory system

    • Most reptiles have closed circulation

    • Contain a three-chamber heart

      • Consisting of two atria and one ventricle.

    • There is little mixing of oxygenated and deoxygenated blood in the three-chamber heart.


General Characteristics

  • Organs for water retention

    • Metanephric kidneys:

      • excretes uric acid or urea which allows them to occupy terrestrial habitats

    • Salt glands:

      • Located near nose/eyes

      • Secretes a salty fluid

  • All reptiles have better body support and more efficiently designed limbs for travelling on land


General Characteristics

  • Circulatory system

    • Exceptions to these characteristics:

      • Crocodilians have a complicated four-chamber heart

        • This heart is capable of becoming a functionally three-chamber heart (during dives)

      • Some snake and lizard species (e.g., monitor lizards and pythons) have three-chamber hearts that become functional four-chamber hearts (during contraction)


General Characteristics

  • Respiratory system

    • All reptiles breathe using lungs.

      • VERY well developed lungs

      • Only a few use skin to breathe (sea snakes)

    • Most reptiles do NOT have a muscular diaphragm (like mammals)

      • Crocodilians have a muscular diaphragm

    • Turtles & Tortoises.

      • Aquatic turtles have developed more permeable skin, and even have gills in their anal region


General Characteristics

  • Nervous system

    • Advanced nervous system compared to amphibians.

    • 12 pairs of cranial nerves.

    • Hearing is underdeveloped

    • All other senses are highly developed

    • Small brain (but, cerebrum is large)

    • Contain Jacobson’s organ

      • Specialized organ for smell (odors carried to this organ via the tongue)


General Characteristics

  • Reproduction system

    • Most reptiles reproduce sexually.

    • Asexual reproduction has been identified in in six families of lizards and one snake.

    • No larval stages.

    • Internal fertilization (copulatory organs)

      • Sperm – testes, Egg - ovaries


General Characteristics

  • Reproduction system, cont.

    • Contain amniotic egg

      • Permits rapid development of large young in relatively dry environments

      • Provides nourishment for growing embryo

      • Provides protection (shell) from environment

      • Allows for sufficient gas exchange

      • Reduces water loss


Classification
Classification

  • Kingdom Animalia

  • Phylum Chordata

  • Class Reptilia

    • They are represented by four surviving orders:

      • Crocodilia

      • Rhynchocephalia

      • Squamata

      • Testudines


Classification1
Classification

  • Order Crocodilia

    • Ex: crocodiles, caimans and alligators

    • 23 surviving species

    • Body shape: elongated, robust, reinforced skull and massive jaw muscle structure

    • Teeth in sockets

    • Four-chambered heart

    • Can vocalize

    • Oviparous (eggs are guarded heavily by mother)

    • Will lay 20-50 eggs at a time

Male Crocodile courtship


Classification2
Classification

  • Rhynchocephalia

    • Ex: tuataras from New Zealand

    • 2 surviving species

    • Lizard-like body form

    • Slow-growing animals that live in burrows

    • VERY good eyesight (have cornea, lens and retina)


Classification3
Classification

  • Squamata

    • Ex: lizards, snakes, (specific ex: gila monster, python, monitor lizard)

    • Approximately 7,600 species

    • Most diverse group of reptiles

    • Kinetic skull (mobile/moveable)

    • May contain fangs (with poison)

    • May contain heat-sensing organs (pit organs – in pit vipers)


Classification4
Classification

  • Testudines

    • Ex: turtles, tortoises

    • Approximately 300 species

    • Enclosed in shells consisting of carapace and plastron (breastplate)

    • No teeth, but contain keratinized plates inside mouth for gripping food

    • Oviparous

      • Nest temperatures determine sex of offspring

      • Low temp = males, high temp = females


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