26.2 Reptiles Reptiles are a diverse group. Reptiles share several characteristics. –ectotherms –covered with dry scales –reproduce by laying or retaining amniotic eggs –three-chambered heart (most) –cloaca Evolutionarily, what problem did reptiles have to overcome?

26.2 Reptiles KEY CONCEPT Reptiles were the first amniotes.

26.2 Reptiles Reptiles have two reproductive strategies. –Oviparous reptiles deposit eggs into an external nest. –Viviparous reptiles retain eggs and give birth to live offspring.Viviparous reptiles

26.2 Reptiles Reptiles have been evolving for millions of years. Over time, amniotes evolved into three different groups. –synapsids –anapsids –diapsids

26.2 Reptiles The diversity of ancient reptiles led to the evolution of modern reptiles, birds, and mammals.

26.2 Reptiles There are four modern groups of reptiles. Turtles and tortoises Lizards, worm lizards and snakes Crocodilians tuatara

26.2 Reptiles There are four modern groups of reptiles. Turtles, tortoises, and terrapins are the remaining anapsids. –Unique characteristic: bony shell encases body –200 species

26.2 Reptiles The Turtle Shell Carapace: top Plastron: bottom fused bones connected by bony bridges on the sides and fused to the vertebrate and ribs on the inside So successful an adaptation that everything else evolved around it –No running or jumping or flying turtles! –Opportunistic eaters Lures, ambushLures

26.2 Reptiles The type of limbs tells a lot about the habitat of a turtle

26.2 Reptiles Sphenodonts are closely related to lizards. –diapsids –primitive characteristics –One living species, Tuatara in New Zealand

26.2 Reptiles Snakes and lizards are very closely related and share a number of features. –diapsids –shed skin at regular intervals –flexible skull –Jacobson’s organ brain tongue Jacobson’s organ

26.2 Reptiles Survival Adaptations Freezing Losing tail Changing color Threat displays Lizards can run but snakes….

26.2 Reptiles video

26.2 Reptiles Instantly recognizable by outer appearance Large toothy snout Compressed tail Important characteristics are internal! Heart & brain more advanced Crocodilians are more closely related to birds.. –diapsids –semi-aquatic predators –23 species

26.2 Reptiles Adaptations as an aquatic predator? Eyes, nostrils and ears high on head in same plane 3 rd eyelid (nictitating membrane) Nostrils and ears can close when dive Valve at the back of the mouth closes (glottis) for catching prey w/o drowning Muscular compressed tail Webbed feet Four chambered heart

26.2 Reptiles Crocodilian locomotion Belly crawl High walk Gallop Swimming Jumping

26.2 Reptiles Alligators versus crocodiles? Alligator Rounded snout (u shaped) Upper teeth overlap and hide bottom teeth Lack modified salivary glands into functional salt glands Pressure sensory organs only around jaws Crocodile Pointy V shaped snout Teeth interlock Salt glands for living in brackish and salty water Pressure sensory organs on virtually every scale

26.2 Reptiles Threats to Reptiles (Conservation) H I P P O Habitat Loss Introduced Species Pollution Population (people) Overconsumption of resources Dilemma Don’t buy wild caught reptiles for pets Don’t buy products from reptiles – turtle soup, items made from turtle shells, reptile skin boots/belts Appreciating reptiles