Reptiles and Amphibians

What is the difference between a reptile and an amphibian?

Answer.. Reptiles have scales. Amphibians have smooth skin (although some are warty). Reptiles are total land animals. Amphibians need the water, but this is not always true. There are many marine reptiles, but they must go ashore to lay their eggs (except the sea snake) There are also amphibians that are able to spend their whole lives out of the water. Reptiles use hard-shelled, amniotic eggs for their babies. All amphibians have soft jellylike eggs.

Amphibians….

Important Characteristics Skeletons are bony, notochord absent, and exoskeleton absent. Body forms vary greatly. Most species have four legs. Forelimbs smaller than hind limbs. Webbed feet often present, no true nails or claws. Forelimbs usually have four digits.

Characteristics continued… Skin smooth and moist with many glands; no scales are present. Mouth large with small teeth and two nostrils. Respiration by lungs, skin or gills. Three chambered heart. Ectothermal.

Amphibian Orders Order Gymnophiona – Caecilians. Order Caudata – Salamanders Order Anura – Frogs and Toads

Order Caecilians

Characteristics 160 species of elongated, limbless, burrowing creatures. They occur in the tropical rainforests of South America.

Order Caudata

Important Characteristics 360 species that mostly are found in Northern temperate regions. Most salamanders have limbs at right angle to their bodies. They are also carnivorous.

Order Anura

Characteristics 3450 species They occupy a great variety of habitats. Aquatic mode of reproduction and water- permeable skin cause them to stay close to water. No tails present in adults.

The Endangered Goliath Frog – They can be over 2 ½ feet in length and weigh close to 10 pounds. They eat rats and ducks.

Reptiles

General Characteristics Ectothermic Scales or scaly skin Internal fertilization Lay amniotic eggs Clawed feet Lungs for respiration Most tetrapods

Important Characteristics They have tough, dry, scaly skin, which offers protection and protects them from drying out. Two paired limbs usually with five toes Skeleton is well ossified. They have a three chambered heart and they also are ectothermic. They respire by lungs, no gills!

Characteristics continued… Efficient jaws for crushing and gripping prey. Efficient strategies for water conservation. Nervous system is a lot more complex than amphibians.

Circulatory System (3 chambered heart)

Excretion Kidneys filter out nitrogenous wastes from blood Reptiles that mostly live in water excrete their wastes in the form of ammonia Terrestrial reptiles excrete uric acid (birds as well)

Nervous System More advanced than amphibians. Jacobson’s Organ: An extrasensory organ in the roof of a snake's mouth Sharpens its sense of smell. Two hollow, highly sensitive saclike structures Allows it to track both prey and potential mates

Jacobson’s Organ

Pit vipers, pythons, and some boas have HEAT SENSING ORGANS “Pit" organ located between the eye and the nostril on each side of the head. Detects heat given off by warm-blooded prey

ENDOCRINE THYROID: located above heart Makes hormones that control heart rate, blood pressure; cell development and growth PANCREAS controls blood sugar levels Glands that make hormones that control other body organs

Order Testudines (Turtles)

Turtle characteristics Their bodies are enclosed in a shell. The shell is composed of two layers: an outer horny layer of keratin and an inner layer of bone. Bones are fused. They have poor hearing, but good senses of smell, vision and color perception.

Order Squamata This composes 95 percent of all reptiles and includes lizards, snakes and worm lizards. Snakes have two specializations: elongation of body and displacement and rearrangement of internal organs. They are specialized to eat large prey. Skulls have mobile joints

Suborder Lizards

Suborder Amphisbaenia: Worm Lizards

Suborder Serpentes: Snakes

Order Sphenodonta: Tuataras Two living species. They are lizard like and live in burrows for extended periods of time.

Order Crocodilia

Important characteristics The only surviving species of the same lineage that gave rise to dinosaurs. All crocodilians have an elongate, robust, well-reinforced skull and massive jaws giving a wide gap and rapid, powerful closure. They are carnivorous and occasionally prey on people.