Transcript Reptiles
Reptiles Characteristics of a Reptile Vertebrate animals Lungs Scaly skin Amniotic egg Characteristics of Reptiles – Adaptations to life on land More efficient lungs and a better circulatory system for life away from water Scaly skin provides protection against the elements and desiccation The amniotic egg protects against desiccation Reptile Lungs- Another Adaptation to Life on Land A more efficient respiratory system Reptiles use two efficient lungs (except snakes – they only have one long functional lung that fits their bodies, the other is vestigial) Kidneys produce urine in the form of uric acid Uric acid crystallizes when concentrated, and is eliminated as a white paste (like birds) Urine is either passed out directly through the cloaca, or stored in the urinary bladder where water is further reabsorbed Excretion Scaly Skin An adaptation to life out of water Waterproof Dry, leathery Protective scales Must be molted Watertight Skin Reptile are covered by thick, dry, scaly skin that prevents water loss Cells with a high keratin content Lipids and proteins in the skin make it watertight conserving water and guarding against injury, infection and wear and tear Reptile eggs have a leathery shell Has several membranes Contains yolk rich in nutrients for embryo Amniotic Egg – Reptiles and Birds Amniotic Egg Membranes Amnion – thin membrane holds the fluid the embryo floats in Yolk sac – holds the yolk (fatty food) for the developing embryo Allantois – holds embryos nitrogenous wastes Chorion – surrounds all the other membranes; protects embryo The Amniotic Egg – adaptation to life on land Amphibians are not able to move away from the water because their eggs would desiccate Reptiles eggs prevent desiccation Reptile Feeding Ex. 1: Iguana Herbivores – tear plants using teeth and jaws Have long digestive systems Carnivores Snakes – have extendible jaws to swallow their prey whole. Carnivores Some snakes have a diet of eggs exclusively. They swallow the egg whole, pierce the shell with a specialized section of the vertebrate, suck out the insides and regurgitates the shell Carnivores The king cobra eats other snakes Breathing Tube Carnivores Monitor lizard – kills prey with sharp teeth and powerful jaws Carnivores Chameleons – have long sticky tongue that they flip out to catch flying insects . Larger cerebrum/ cerebellum than the amphibians Daytime reptiles have good color vision: turtles can see color better than humans Nervous Systems Frog Brain Alligator Brain Excellent Sense of Smell Have pair of Snakes nostrils Also have special organs (vomeronasal organs) on roof of mouth Tongue picks up chemicals and brings them to the vomeronasal organs to “taste” the air Hearing Most lizards have simple ears like an amphibian: external tympanum, single bone to transfer sound to inner ear . (we have an internal tympanum and 3 bones) Snakes have no ears and are deaf – they “hear” the vibrations from the ground Hearing - tortoises Tortoises do not have a tympanum, but have a soundconducting patch of skin on their head. A “Red Ear Slider” turtle Heat Sensors Pit vipers are able to detect heat, to obtain a temperature image o their environment Normal view Infrared view Combined view Pit vipers Snakes - movement Snakes press their ventral scales against the ground Muscles around the ribs expand and contract in waves causing the sshaped movement Movement A snake has a backbone of 100 to 400 vertebrae, each of which has a pair of ribs attached. - Providing the framework for thousands of muscles The interaction of bones, muscles, and skin enables asnake to move in one of three basic ways: 1. Lateral undulation 2. rectilinear movement 3. side winding. Gecko – suction cup toes Geckos have special flaps of skin on its toes – creating very sticky appendages Reptile Reproduction Most have internal fertilization Penis delivers sperm into cloaca of female Reptile Reproduction Internal fertilization Male inserts penis into female’s cloaca Female’s body coats the embryos in protective shell, with membranes and yolk sac Reptile Reproduction Most reptiles are oviparous Some provide minimal care Modern Reptiles Reptiles are classified into 16 orders, 12 that are extinct. - 4 surviving-6, 000 species Reptiles occur worldwide except in coldest regions - Human intervention-major impact 4 living orders of Class Reptilia: - 1. Rhynchocephalia, - 2. Chelonia, - 3. Crocodilia, - 4. Squamata Rhynochocephalia Only living speciesSphenodon punctatus- the tuatara - Inhibit islands of coast of New Zealand - Resembles a large lizard about 60 cm long - Has an inconspicuous third eye on top of its headparietal eye- functions as a thermostat- protects from overheating - Active at low temperatures and feed at night on insects, worms and small animals Chelonia Order consists of about 265 species of turtles and tortoises - Tortoise are terrestrial Chelonia (Galapagos tortoises) - Turtles- chelonians that live in water - Body covered by a shell made of hard plates- 2 parts- a carapace and plastron - Shape is modified for variety of ecological demands - retract heads, swimming - Forelimbs of a marine turtle have evolved into flippers and freshwater turtles have webbed toes - Migratory behavior of sea and river turtles -return to land to lay eggs Crocodilia Order composed of 20 species of large lizard-shaped reptilescrocodiles, alligators, caimans and gavials - Descendants of archosaurs Crocodilians live in or near water in tropical/ subtropical regions of the world - Crocodiles- nocturnal animals; Africa, Asia and Americas - Alligators - China and southern U.S. - Caimans- Central Americasome in Florida - Gavials- eat fish; long and slender snout- live only in Burma and India Carnivorous- hunt by stealthfeatures adapted for this behavior - Eyes on head, nostrils on top of snout -see and breathe while in water - Valve to prevent water from entering air passage - Parental care- both parents care for young by carrying in jaws until development Squamata Order consists of 5,640 species of lizards and snakes - Loosely jointed upper jaw and paired reproductive organs in males - Structurally diverse Lizards- presence of limbs - Common lizards- iguanas, chameleons, skinks and geckos - Live everywhere except Antarctic - Special adaptations- agility and camouflage - 2 species are venomousGila monster (SW U.S.) and beaded lizard (western Mexico) - Most prey on insects or small Blend with background - chameleons- remain inconspicuous and fend off enemies - Horned lizards- spiked armor, when disturbed they inflate themselves, gape, hiss and squirt blood from eyes - Skinks and geckos- lose their tails and regenerateautotomy- escape from predators - Most lizards are small- .3m in length; iguanas- 1m in length - Largest lizards- monitorsKomodo dragon (Indonesia) 3m - Consume prey whole and use tail as defense weapon - Order Sphenodontida (Rhynchocephalia) - tuatara • 2 spp. - max. length c.600mm. • most primitive living reptile, unchanged for 200my, relatives extinct 60 mya. • primitive features: pineal eye structure, foramen (openings) in skull, teeth fused to jawbone, no ear opening. • temperature-dependent sex determination in incubating eggs. • caudal autotomy - lose tail voluntarily; fracture planes within vertebra; tail regrowth. • formerly widespread, now restricted to c.30 offshore islands. NZ reptile fauna Sphenadon punctatus Order Squamata - lizards & snakes Lizards: • at least 80 lizards species and subspecies of lizard known in New Zealand (still being discovered and described). • caudal autotomy. • lizards represented by geckos and skinks in New Zealand Robb 1980 Robb 1980 Geckos - flattened body with short legs granular scales, transparent scale over eye eyelid non-moveable, cleaned by the tongue able to climb vertical surfaces - specially adapted gripping bristles (lamellae) underneath toes - can make noises - chattering sound when disturbed or threatened - most southern geckos in the world, largest species (kawekaweau, extinct) - NZ species retain eggs in body to give birth to live young (ovoviviparity 2 NZ genera - Hoplodactylus – 9 spp. (1 extinct), brown, limited colour change, nocturnal - Naultinus – 7 spp., green, diurnal Skinks - elongated body, rounded in cross-section, long tapering tail. - very agile. - flat, shiny, overlapping scales. - moveable eyelids (blink). - most ovoviviparous. 2 NZ genera - Cyclodina – 6 spp. (1 extinct), diurnal. - Oligosoma (Leiolopisma) – 21 spp. (1 extinct), nocturnal or crepuscular. - [1 introduced sp. – rainbow skink, northern Nth Is.] Other reptiles? - turtles - snakes - crocodiles Evolution of Reptiles TRANSITION FOSSILS show that there was a slow and steady evolution from amphibians to reptiles. Age of the Large Reptiles Approximately 195 million years ago, the mammallike reptiles that populated the world disappeared and were replaced by the dinosaurs Mass Extinction – 65mya Scientists not sure why the dinosaurs disappeared Possibly the world was hit by a meteor Only relatively small reptiles were left behind Major radiation into all ways of life; terrestrial, aquatic, aerial. Ichthyosaurs: fully aquatic, but air breathing. A reptile equivalent to whales or porpoises. Mostly fish eating. Pterosaurs = hang glider wings. Archosaurs = major dinosaur groups Plus crocodiles, and bird ancestry. A very diverse and complex group. - die out at Cretaceous boundary = meteor?