REPTILE CLASSIFICATION

CLASS REPTILIA

• Members of this class were the first vertebrates to have amniotic eggs.

• These eggs have extra membranes that protect the embryo from drying out, it cushions the embryo, helps with gas transfer, and stores waste materials.

• They also have leathery, hard shells that protect the developing embryo, albumen that provides moisture and nutrients, and yolk that supplies food.

• All of these features are adaptations for development on land.

CLASS REPTILIA

• Reptiles are characterized by a skull with one surface for attaching to the first neck vertebra; respiration by lungs, kidneys, internal fertilization, and amniotic eggs.

CLASS REPTILIA

• They also have dry skin with keratin scales. • Keratin is a protein that helps prevent water loss.

CLASS REPTILIA

• Members of 3 of the 4 orders live on all continents except Antarctica.

• Reptiles are a dominant part of ecosystems only in tropical and subtropical regions.

• The 4 orders are:

• Testudine• Rhynchocephalia• Squamata• Crocodilia

ORDER TESTUDINES (CHELONIA)

• Members of this order are the turtles. • There are about 225 species. • They have a bony shell, limbs that attach

internally to the ribs, and a keratin beak instead of teeth.

• The dorsal portion of the shell is called the carapace and the ventral portion of the shell is called the plastron.

ORDER TESTUDINE

• In some turtles, the shell has flexible areas, or hinges, that allow the front and back edges of the plastron to be raised.

• The hinge allows the shell opening to close when the turtle goes into the shell.

• Turtles have 8 cervical vertebrae that form an S-like shape, which allows the head to go into the shell.

ORDER TESTUDINE

• Turtles have long life spans. • Most live over 14 years. • Large tortoises, like those on the Galapagos

Islands, may live over 100 years. • Tortoises are entirely terrestrial and do not have

webbed feet.

ORDER TESTUDINE

• All turtles lay eggs. • Females use their hindlimbs to dig nests in the

soil. • They lay eggs and cover them with dirt, usually in

clutches of 5-100 eggs. • Development takes from 4 weeks to 1 year, and

the parent does not attend the eggs during this time.

• The young are independent of their parents when they hatch.

ORDER TESTUDINE

• Turtles have become very vulnerable to extinction because of slow rates of growth and long juvenile periods.

• Turtle hunting and young turtles being eaten have severely threatened some species—especially the sea turtles that nest on certain beaches each year.

ORDER RHYNCHOCEPHALIA

• The 2 surviving species of this order are the tuataras.

• These are lizard-like reptiles.

ORDER RHYNCHOCEPHALIA

• Tooth attachment and structure make them different from other reptiles.

• 2 rows of teeth on the upper jaw and a single row of teeth on the lower jaw cause a bite that can decapitate a small bird.

ORDER RHYNCHOCEPHALIA

• Tuataras are only found on remote islands of New Zealand and are protected by law.

• They lay eggs and share underground burrows with seabirds.

• They will come out of their burrows at dusk and dawn to feed.

• They will eat insects and some small vertebrates.

ORDER SQUAMATA

• This order is divided into 3 sub-orders.

Suborder Sauria (lizards)

• There are about 3300 species of lizard in this suborder.

• Different than snakes, lizards usually have 2 pairs of legs and have some differences in their jaws.

• Lizards vary in length from a few centimeters to as long as 3 meters.

Suborder Sauria (lizards)

• Many lizards live on the surface and will hide under rocks or logs when necessary.

• Others are burrowers or tree-dwellers. • Most lizards lay eggs; some have eggs that

develop internally and are fed by the egg; some have eggs that develop internally and are fed by the female.

• They will usually put eggs under rocks or debris or in burrows.

Suborder Sauria (lizards)

• Geckos, common to human dwellings, are short and stout.

• They are nocturnal, and unlike most lizards, are capable of clicking sounds.

• They have large eyes that are adapted for night vision.

• They also have adhesive disks on their feet to help cling to trees and walls.

Suborder Sauria (lizards)

• Iguanas have robust bodies, short necks, and very distinct heads.

• This group includes the marine iguanas of Galapagos Islands and the flying dragons (Draco) of Southeast Asia.

• The flying dragons have folds of skin supported by ribs.

• Like an umbrella, the ribs can expand to form a gliding surface.

• When this lizard launches, it can glide 30 meters or more!

Suborder Sauria (lizards)

• Another group of iguanas, the chameleons, live mainly in Africa and India.

• They are adapted to tree-living and use a long, sticky tongue to capture prey.

• Anolis, or the “pet store” chameleon, is also an iguana, but is not a true chameleon.

• Chameleons and Anolis are well known for their ability to change color in response to light, temperature, or their behavior condition.

Suborder Sauria (lizards)

• The only venomous lizards are the Gila monster (Heloderma suspectum) and the Mexican bearded lizard (Heloderma horridum).

• These heavy lizards are native to southwestern United States.

• Venom is released into grooves on the surface of the teeth and injected into prey as they chew.

• Lizard bites are seldom fatal to humans.

Suborder Serpentes (snakes)

• There are about 2300 species of snake. • About 300 species are venomous. • Worldwide, about 30,000-40,000 people die from

snake bites each year. • Most of these deaths are in Southeast Asia. • In the United States, fewer than 100 people die

from snake bites each year.

Suborder Serpentes (snakes)

• Snakes are long and do not have limbs. • Pythons and boas do have pelvic girdles that do

not function.• The skeleton may contain more than 200

vertebra and pairs of ribs. • Joints between the vertebrae make the body very

flexible.

Suborder Serpentes (snakes)

• Snakes have skull adaptations that help them swallow large prey.

• These include upper jaws that are movable on the skull, and upper and lower jaws that are loosely joined so that each half can move independently.

Suborder Serpentes (snakes)

• Other differences from lizards are the way the eyes focus and the structure of the retina.

• The long body and narrowing of the body has resulted in the reduction or loss of the left lung, and displacement of the gallbladder, the right kidney, and often, the gonads.

• Most snakes lay eggs, but some, like the new World boas and garter snakes, give birth to live young.

Suborder Amphisbaenia (worm lizards)

• There are about 135 species of worm lizard. • They are specialized burrowers that live in the

soil in Africa, South America, the Caribbean, and the Mideast.

• Most are legless, and their skulls are shovel shape.

Suborder Amphisbaenia (worm lizards)

• They have a single tooth in their upper jaw and this distinguishes them from other vertebrates.

• Their skin has ringlike folds called annuli and are loosely attached to the body wall.

• Muscles of the skin cause it to bulge outward, forming an anchor against a burrow wall.

• They move easily forward or backward. • They eat worms or small insects.• They also lay eggs.

ORDER CROCODILIA

• There are 21 species of crocodilian. • Members of this order are different from other

reptiles by having certain skull characteristics; openings in the skull in front of the eye; triangular rather than circular eye orbits; and laterally compressed teeth.

• Members of this group include alligators, crocodiles, gavials, and caimans.

ORDER CROCODILIA

• Crocodilians have a long snout and is often used to capture food by a sideways sweep of the head.

• The nostrils are at the tip of the snout, so the animal can breathe while mostly underwater.

• Air passageways lead from the head to the rear of the mouth and throat.

• They have a flap of skin near the back of the tongue that forms a watertight seal, allowing breathing without inhaling water in the mouth.

ORDER CROCODILIA

• A plate of bone, called the secondary palate, separates the nasal and mouth passageways.

• The tail is muscular and long and is used for swimming, offensive and defensive maneuvers, and attacking prey.

• Teeth are used only for seizing prey. • Food is swallowed whole, but if it is too large, they will tear

it apart by holding onto a limb and rotating their bodies until the prey is torn apart.

• The stomach is like a gizzard, and they will swallow rocks and other objects to help break apart and digest food.

• Crocodilians do lay eggs and provide parental care to their hatchlings.