Reptiles

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

Diversity 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"

◦ 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 preykill/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 1.Metanephric kidneys:  excretes uric acid or urea which allows them to occupy terrestrial habitats 2.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 General Characteristics

Kingdom Animalia Phylum Chordata Class Reptilia Class Reptilia ◦ They are represented by four surviving orders: 1.Crocodilia 2.Rhynchocephalia 3.Squamata 4.Testudines 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 eggs at a time Classification Male Crocodile courtship

◦ 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) 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) 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 Classification