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Dive into the fascinating world of reptiles and amphibians! Learn about their unique characteristics, habitats, and diversity. Discover how these creatures adapt to their environments and the intriguing aspects of their life cycles. Explore the diverse species of frogs, toads, salamanders, and reptiles, from tropical regions to freezing climates. Uncover the remarkable traits of turtles, caecilians, and more.
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Characteristics of Class Amphibia • Most amphibians are tetrapods, meaning they have four limbs, but some are limbless. • Amphibians have smooth, moist skin. • Amphibians respire by lungs, skin, and gills; either separately or in combinations. • Amphibians have a 3-chambered heart, with two atria and one ventricle. • Amphibians are ectotherms, meaning they require an external source of heat.
Caecilians: Order Gymnophiona (Apoda) • Caecilians have a long slender body that is limbless and they live in burrows. • Caecilians live in tropical regions. • Caecilian's eyes are small and they are almost completely blind. • Caecilians are carnivores that eat mostly worms and other invertebrates. • Fertilization is internal, but eggs are usually deposited in moist ground near the water.
Salamanders: Order Urodela (Caudata) • Salamanders are tetrapod amphibians with tails. • Most of the salamanders in North America are less than 6 inches (15 cm) long. • Some are much larger, like the giant Japanese salamander that can exceed 4-5 feet (1.5 meters). • Most salamanders have four equal-sized limbs set at right angles to their body. • Salamanders are typically carnivores that prey on worms, arthropods, and mollusks.
Frogs and Toads: Order Anura (Salientia) • Frogs and Toads lack tails as adults. • All frogs and toads bear a tail in the larva stage. • Frogs and Toads are adapted for jumping. • The name Anura means “without a tail” and Salientia means “jumping or leaping”. • Eggs of frogs and toads hatch into a tadpole, having a finned tail, internal and external gills, no legs, and tadpoles are herbivores.
Frogs and Toads: Order Anura (Salientia) • Adults are much different than the larval form. • After tadpoles go through metamorphosis, frogs and toads lose their tail and gills,develop legs, and become carnivores. • Frogs and Toads vary in size from the West African Goliath frog (30 cm long or 1 ft.), to some that are less than 1 cm in length. • The Goliath frog can consume rats and ducks.
Frogs and Toads: Order Anura (Salientia) • Frogs are found all over the world, but the majority of them are found in tropical regions. • Those that live in colder climates, hibernate in the winter. Some frogs hibernate in the soft mud of ponds and streams. • Terrestrial frogs, such as tree frogs, hibernate in the humus (leaf litter) of the forest floor. • Some can even withstand freezing temperatures by converting glycogen from their liver into glucose, which prevents ice-crystal formation.
Class Reptilia • Body is covered in scales made of keratin. • Most are tetrapods, some are limbless. • Respiration is by lungs, not by skin or gills. • 3-chambered heart in most, with the exception of the crocodilians which have a 4-chambered heart. • Ectothermic; body temperature is modified bybehavioral thermoregulation. • Fertilization is internal • Amniotic eggs covered with leathery shells with internal embryonic membranes.
Characteristics of Reptiles • Reptile scales are different than fish scales. • The scales on a reptile are made of keratin and are similar in material to mammal skin. • Reptile eggs are amniotic, meaning they have internal membranes, (like the chorion and allantois) which help exchange gas and remove metabolic waste. • The tough leathery shell also allows the eggs to be laid in dry terrestrial environments.
Characteristics of Reptiles • Reptiles have a double pump circulation with a systemic (body) and pulmonary (lungs) circulation. • Reptiles do not have completely separated ventricles, which causes partial mixing of deoxygenated and oxygenated blood. • Reptilian lungs are more efficient than amphibian lungs.Their rib cage can expand and contract, but, they lack a muscular diaphragm like mammals.
Turtles: Order Testudinata • The body of a turtle is enclosed in two shells; the dorsal shell called the carapace and the ventral shell called the plastron. The carapace is fused with the ribs and the vertebrae. • Shell provides protection for the head, arms, and legs, which can be retracted into the shell. • The turtle cannot expand the chest to breath so they use abdominal and pectoral muscles to draw air into the lungs.
Turtles: Order Testudinata • Turtles lack teeth, but they have beak-like jaws lined with tough plates made of keratin. • Turtles are almost completely deaf, but they have a good sense of smell and vision. • Turtles are oviparous, with internal fertilization. • All turtles, including marine forms bury their amniotic eggs in the ground. • Nest temperatures determine the sex of the turtles; low temperatures males, high temperatures females.
Turtles: Order Testudinata • Leatherback marine turtles can reach 2 meters in length and weigh up to 725 kg (about as heavy as a large moose at 1500 lbs) • Some land tortoises like the Galapagos Island tortoises can weigh several hundred kilograms. • Most tortoises are slow moving, moving only a few hundred meters per hour. • Their low metabolism may explain their longevity. Some living over 150 years.
Order Squamata: Lizards and Snakes • Approximately 95% of all known living reptiles belong in this order. • One feature of the order squamatathat has made them some of the most successful and diverse of all the reptiles is the kinetic skull. • The kinetic skull is an adaptation that allows the snout to be tilted upward, in order to capture and manipulate their prey and increase the force of the jaws.
Lizards: Suborder Sauria • Suborder Sauria (a suborder of the order Squamata) includes geckos, iguanas, skinks, and chameleons. • Most lizards are tetrapods, except for the glass lizards which are limbless. • Lizards have movable eyelids, snakes do not. • Lizards have rods and cones in their eyes which give them excellent daytime vision, except some nocturnal geckos that have only rods. • Most lizards have external ears, snakes do not.
Lizards: Suborder Sauria • Lizards are also well adapted to living in hot, arid climates like the desert. • Lipids (fats) in their skin minimize water loss. • Concentrated urine conserves water. • Some lizards, like the Gila monster of the southwestern U.S., store fat in their tails, which they use for an energy and water reservoir. • Ectotherms do not require as much energy to live as do endotherms.
Snakes: Suborder Serpentes • Snakes are limbless reptiles and they usually they lack pelvic and pectoral girdles. • Numerous vertebrae and ribsprovide support, protection, and more leverage for the muscles to increase efficiency in locomotion. • The kinetic skull enables snakes to swallow prey several times their size. • Snakes do not have movable eyelids, but they do have permanently covered transparent eyelids.
Snakes: Suborder Serpentes • Snakes do not have any external ears. • Snakes do have internal ears that can detect limited low frequency sounds. • Snakes are sensitive to ground vibrations. • Most snakes have relatively poor vision. • Some arboreal (tree-dwelling) snakes have excellent binocular(stereoscopic) vision, that is useful for tracking prey through branches.
Snakes: Suborder Serpentes • Probably the most advanced sensory organs used by snakes is called the Jacobson's organ, which is an organ that can detect chemicals in the air from a pair of pits that are found on the roof of their mouth. • The Jacobson's organs are lined with olfactory sensory neurons. • Their forked tongue, flicks the air to pick up scent molecules, which are carried to the Jacobson's organ.
Snakes: Suborder Serpentes • Most snakes kill their prey by grabbing it and swallowing it whole, but this can be dangerous. • Constrictor snakes, kill their prey first by constriction, then swallow the prey whole. • Some constrictors can swallow prey as large as deer, leopards, and even crocodiles. • The muscles of constrictors are very large, but, the large muscles slow them down. • So most constrictors wait and ambush their prey rather than seek out their prey.
Snakes: Suborder Serpentes • Other snakes kill their prey with venom before swallowing it whole. • Vipers (members of the Viperidae family) have large, movable fangs at the front of their mouths. • Elapids ; Cobras, mambas, and coral snakes (members of the Elapidae family) have permanently erect fangs. • Some vipers are called pit vipers because they possess special heat-sensitive pit organs on their heads that detect infrared heat produced by endotherms (warm-blooded animals).
