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Reptiles Characteristics of Reptiles 1. Strong, bony skeletons and feet with claws 2. Ectothermic (cold-blooded) 3. Dry scaley skin 4. Amniotic eggs 5. Respiration with lungs 6. Ventricle partially divided 7. Internal fertilization Order Rhynchocephalia Tuatara - Only found in New Zealand, they have no external ears and a 3rd eye Turtles and Tortoises • Turtles and tortoises differ from other reptiles in that their bodies are encased within a hard, bony, protective shell. Many of them can pull their head and legs into the shell for effective protection from predators. • Today’s turtles and tortoises differ little from the earliest known turtle fossils, which are more than 200 million years old. Still under debate… • Turtles are the last big living vertebrate group to be placed firmly on the tree of life • Three fields in particular — paleontology, developmental biology and microbiology/genomics — disagree about how, and from what, turtles may have evolved. • Some scientists argue turtles are more closely related to snakes and lizards other feel they are birds and crocodiles. • Turtles and tortoises lack teeth but have jaws covered by sharp plates. • Many are herbivores, but some, such as the snapping turtle, are aggressive carnivores. Turtles vs. Tortoises • There are 260 species of turtles, but only seven species of sea turtles in the world, 5 of which are found in the south east. • Most turtles live in the water and tortoises on land. • While most tortoises have a domeshaped shell, water-dwelling turtles have a streamlined, disk-shaped shell that permits rapid maneuvering in water. The top of a turtle's shell is the carapace, the bottom is the plastron Is this a turtle or a tortoise? Order Squamata Snakes & Lizards • • • • Have legs (vestigial on snakes) clawed toes external ears moveable eyelids Komodo Dragon • When hunting, Komodo dragons rely on camouflage and patience, lying in wait for passing prey. • When a victim ambles by, the dragon springs, using its powerful legs, sharp claws and serrated, shark-like teeth to eviscerate its prey. • Their saliva contains over 50 strains of bacteria, and within 24 hours, the stricken creature usually dies of blood poisoning. • Dragons calmly follow an escapee for miles as the bacteria takes effect, using their keen sense of smell to hone in on the corpse. • A dragon can eat a whopping 80 percent of its body weight in a single feeding. Snakes All snakes swallow their prey whole. Snakes can be constrictors or venomous to kill prey. One day, a baby snake went over to his dad and said “Dad, are we the kind of snakes that are venomous, or are we the constricting kind?”. The dad replied “Why do you ask, son?” The baby snake said: “Because I bit my lip.” Myth Busted! • Snake jaws DO NOT DETATCH • The two lower jaws move independently of one another • The quadrate bone is not rigidly attached to the skull, but articulates with the skull at one end and is therefore freely moving. • The elasticity of the ligament between the mandibles allows for further stretching Lost snake species rediscovered! Family Crocodilia • 4 chambered heart • Poikilotherm (cold blooded) • Live in groups known as “pods” Alligator or Crocodile? Crocodilians • There are 23 recognized species of Crocodilians broken down into: (will be 26/27 soon) – 2 Species of Alligators – 14 Species of Crocodiles – 6 Caiman – 1 Gharial • The only place in the world where Crocodiles and Alligators co-exist in the wild is in Southern Florida What’s the difference? • The rounded or shovel shape of the alligator's head versus the triangular tapering shape of the crocodile is the most visual distinguishing features. • Crocodiles usually have an “under-bite” allowing teeth to be seen even with its mouth closed. Dermal Pressure Receptors • Both crocodiles and alligators have small, sensory pits dotted around the upper and lower jaws. • These are capable of detecting small pressure changes in water, and assist in locating and capturing prey. • Crocodiles have similar organs covering virtually every scale on their body, but alligators and caimans only have those around the jaws • Crocodiles and gharials also have functioning modified salivary glands on their tongue. While alligators and caimans also have these structures they appear to have lost the ability to use them for excreting significant amounts of salt. This makes crocodiles more tolerant to life in saline water. • It suggests that crocodiles have a more recent marine ancestry: the ability to migrate across wide marine bodies, and even live there for extended periods. would certainly explain their current wide distribution across different continents. Alligators and caimans have lost much of this osmotic ability to secrete excess salt through the tongue glands, and can only tolerate it for short periods of time. Modern Dinosaurs • Crocodilians date back over 230 million years • Crocodilians have been virtually unchanged for the last 65 million years SuperCroc likely measured about 40 feet (12 meters) long and weighed as much as ten tons. Its jaws alone measured 6 feet (1.8 meters)—as long as a tall human Sarcosuchus imperator, or “flesh crocodile emperor,” lived roughly 110 million years ago, when rivers coursed over what is now subSaharan Africa. Sarcosuchus prowled the rivers’ banks, crushing fish — and other creatures—in its massive jaws. Fossilized skull of Dunkleosteus terrelli, or "terrible fish," a 33foot (10-meter) behemoth that lived 400 million years ago. Scientists used the monster's skull to recreate the musculature of the fish's head and found that its colossal jaws delivered a bite with a remarkable 1,100 pounds (540 kilograms) of force. Bite Force • In the American Alligator (Alligator mississippiensis) has been measured at up to 2,125 P.S.I. and is known to be the 2nd greatest in the animal kingdom • In the Salt Water Crocodile (Crocodylus porosus) has been measured at up to 3,000 P.S.I. and is thought to be the greatest in the animal kingdom • Compare that with a lion at 940 pounds. Bite Force Studies Teeth • Crocodilians have between 70 and 80 teeth at any given time • Teeth are last and replaced continuously with each individual tooth being replaced at a rate of approximately once annually (That’s approximately 2,000 teeth in a lifetime!) • Crocodile vs. Alligator teeth • Nutritional Importance “Egg Tooth” • A modified piece of skin which forms during development of the embryo (Not a true tooth made from bone.) • When the time comes to emerge, the crocodile normally rubs the tip of its snout up and down against the inner membrane of the egg. The sharp egg tooth slices apart the inner membrane, and the hatchling can then push its nose forwards forcefully to crack the outer membrane. This event, where the baby crocodilian pierces the eggshell membrane and sticks its snout out into the air, is called pipping The Amniote Egg Contains a water and food supply for the embryo and can be laid on land. Must be fertilized internally, has a shell Snakes Hatching Parts of the Amniote Egg Amnion = watery environment Yolk = food for embryo Allantois = stores waste Chorion = membrane, gas exchange Albumen = egg white, cushion Juvenile crying http://www.flmnh.ufl.edu/cnhc/images/!amis9b.wav The eye-shine of an alligator (and other nocturnal vertebrates) is caused by a layer of cells called the tapetum lucidum (a Latin phrase meaning "bright carpet"). This structure reflects light back into these cells to increase the amount of light detected and improve the animal's vision in low light conditions.