Aquatic Life – Amphibians & Reptiles In this unit we will continue to discuss the characteristics of aquatic animals categorized as vertebrates (animals with backbones) and focus on amphibians and reptiles. Summaries = Orange Underlined = Vocabulary Image

Review of Taxonomy Kingdom Animalia ◦Phylum Chordata  Subphylum Vertebrata (animals that have backbones) ◦ Superclass Tetropoda (organisms with four limbs)  Class Amphibia  Class Reptilia Image

What is an Amphibian? The word amphibian means “double life” because these animals live both in water and on land. As larva, amphibians live in water and respire using gills. As adults, amphibians are terrestrial (live on land) and breath using lungs. They characteristically have moist skin and lack scales and claws.

Amphibian - Respiration They have moist skin that enables the exchange of gases with the environment (inefficient lungs). Their skin must stay moist to allow for the diffusion of gases. They have mucus glands in the skin that aid with staying moist. /87/Bufo_periglenes1.jpg/300px-Bufo_periglenes1.jpg

Amphibian - Circulation Amphibians have a double- loop circulatory system and a 3- chambered heart as adults.

Amphibian - Reproduction Amphibians use external fertilization for reproduction. They are oviparous and lay eggs that are coated with a jelly-like coating to protect and provide embryos with nourishment. Amphibians must lay their eggs in water or moist places on land so eggs do not dry out.

Amphibian - Excretion Amphibians have a cloaca or a common chamber for the digestive, excretory and reproductive systems. The products (urine, eggs, etc) leave the body through the cloaca. photos/amphib/newt_cloaca.jpg

Amphibian - Metamorphosis Amphibians are the only vertebrate grouping that have a life cycle that includes metamorphosis (a series of changes between larvae and adult). ◦Many insects (invertebrates) exhibit metamorphic changes ◦EX The Butterfly The stages are triggered by the hormone thyroxin. ater/bellfrog_illus.jpg

Amphibian – Adaptations for Water Amphibians have a transparent nictitating membrane which helps to keep eyes moist in air and protected in water. Tympanic membranes in amphibians allow the animals to detect sound waves in air or water (primitive ears) and are found behind the eyes. nictitating%20membrane200.jpg

Order Anura – Frogs & Toads Order Anura includes all frogs and toads (have ability to jump). ◦Frogs have smooth, moist skin ◦Toads have dry, bumpy skin and are Toads have adapted to living in drier environments ow%20banded%20poison%20dart%20frog.jpg

Order Urodela – Salamanders Order Urodela includes salamanders. This order has a long tail, long body and two pair of legs almost equal in size. Some salamanders have gills, some have lungs, some have both. nder.jpg

Order Apoda – Wormlike Amphibians Order Apoda or caecilians have characteristics that make them look like segmented worms. caecilians These legless amphibians are blind or nearly blind and spend their life burrowing through soil (in moist tropical regions).

Between 240 and 150 million years ago, giant reptiles ruled the earth. The dinosaurs eventually died off, but their relatives are alive today. A reptile is characterized as a vertebrate that has dry, scaly skin, breaths with lungs, and lays terrestrial eggs. Today reptiles inhabit large areas of the earth but they cannot live in very cold areas as they are ectothermic. What is a Reptile?

Reptiles have tight-fitting, water-resistant scales made of keratin. Scales prevent water loss from body but do not grow with body so must be shed periodically. Presence of large, strong, legs or limbs close to body quickly on land and in water. Found only on the Galápagos Islands, marine iguanas often wear distinctive white "wigs" of salt expelled from glands near their noses. Photograph by Rob Stewart/Animals Animals— Earth Scenes

Reptile – Respiration Reptiles are respire using reptiles have well-developed lungs. Aquatic reptiles are well adapted to remain submerged underwater for long periods of time. A hawksbill turtle swims just above the seafloor with flippers spread like wings. Hawksbills get their name from their tapered heads, which end in a sharp point resembling a bird's beak. Photograph by Nick Caloyianis

Reptiles have a partially divided, 3-chambered heart (except crocodiles which have a 4- chambered heart). This allows for greater separation of oxygen-rich and oxygen-poor blood. Reptile – Circulation Nile crocodiles are the largest crocodilians in Africa, sometimes reaching 20 feet (6 meters) long. Photograph by Chris Johns

Reptiles have internal fertilization with shelled, terrestrial (can be laid on land) eggs (oviparous) which eliminates dependence on water for fertilization. They have a higher rate of fertilization because sperm are protected from the environment. Females do not need to lay as many eggs. An amniotic egg provides nourishment and protection for developing embryo (yolk is food source). Reptile - Reproduction ing_reptile/clutch_of_eggs.jpg

Video Unlike other sea turtles, female Kemp's ridley turtles come ashore to lay their eggs in the daylight hours. Photograph by Bill Curtsinger

Kidneys filter and the digestive system collect wastes to be excreted from the body. Their excretory system is designed to conserve water with urine that is thick and pasty. Reptile - Excretion

Order SphenodontaSphenodonta The only surviving member of this order is the Tuatara, an endangered lizard found on the islands of New Zealand. Known as a "living fossil" - they have survived unchanged for 150 million years! They have a unique third eye to detect heat. Order Sphenodonta o43597/vanessa/chave/tua.jpg

Order Testudines, or turtles & tortoises, which all have a protective shell fused to their vertebrae. Tortoises (live on land) Freshwater turtles (live on land but feed in the water) Sea turtles (live in the ocean) Order Testudine - Turtles galap_tortoise.jpg

Order Squamata – Lizards & Snakes Order Squamata or lizards & snakes Snakes have lost their legs to increase mobility. Historically snakes had legs, but still have hip bones and a femur. Lizards have legs, claws toes, external ears, and movable eyelids. Green Anaconda – South America Photograph by Claus Meyer/Minden Pictures

Order Crocodilians or crocodiles and alligators. Adapted to hunt with eyes and nostrils above the head so the body can remain submerged when they attack. Crocodiles have a narrow head and long snout; live in tropical regions all over the world. Order Crocodilian – Crocs & Alligators

Video Alligators have a short, broad snout; live in tropical regions of China and USA. They are the only reptile group that takes care of their young. Female crocs lay their eggs in clutches of 20 to 60. After the eggs have incubated for about three months, the mother opens the nest and helps her young out of their shells. Photograph by Steve Winter