Amphibians

What are amphibians? Vertebrates Tetrapods (“four feet”) Ectothermic “both ways of life” Special amphibious traits: Respiration through skin Some amphibians are lung-less Metamorphosis

Amphibian Orders Order Urodela Order Anura Order Apoda

Order Urodela Includes salamanders & newts Have elongated bodies with a tail & four limbs  Smooth, moist skin for cutaneous respiration Less able to stay on dry land than anurans

Order Urodela Size from a few centimeters long to 1.5 meters Nocturnal when live in drier areas Lay eggs in water or damp soil Some bear live young May or may not go through tadpole stage (some hatch & look like small adult)

Order Anura Both terrestrial & freshwater species Tadpole with tail, gills, & two-chambered heart Adults without a tail, four limbs, & lungs Frog skin smooth & moist for cutaneous respiration, while toads is rough & warty (poison glands) Long hind limbs for jumping Long, forked tongue hinged at front of mouth

Order Apoda Includes caecilians Tropical, burrowing, worm like amphibians Legless Small eyes & often blind Eat worms & other invertebrates Average length 30 centimeters, but can grow up to 1.3 meters Internal fertilization Female bear live young

Feeding Larvae: mostly herbivores Adults: mostly carnivores

External Amphibian Anatomy External nares Tympanic membrane – cover ear Nictitating Membrane – transparent eyelid Upper and lower eye lid Trunk Head Forelimb Hindlimb

External nares Tympanic membrane Nictitating Membrane Upper and lower eye lid Trunk Head Forelimb Hindlimb

Other external features Webbed feet Lack of claws Layout of the “hands” can differ

Skeletal System Very similar layout to human skeleton Head, trunk, limbs Lack of rib cage

Skeletal System Skull Scapula Radioulna Humerus Vertebrae Tibiofibula Femur Tarsus Metatarsus Carpus Metacarpus Phalanges *Urostyle

Skeletal System Skull Scapula Radioulna Humerus Vertebrae Tibiofibula Femur Tarsus Metatarsus Carpus Metacarpus Phalanges *Urostyle

Muscular System Submaxillary Control of the Forelimbs: Obliques Deltoid Latissimus dorsi Pectoralis Obliques Recuts abdominus Linea Alba Within Hindlegs: Gastrocnemius Triceps femoris

Muscular System

Muscular System

Digestive System Tongue sticky, forked, & hinged at front of mouth so can be extended out to catch insects Can pull eyes inward to help swallow food Two, sharp, backward-pointing  vomerine teeth in roof of mouth help prevent prey from escaping Maxillary teeth line the edge of the upper jaw

Digestive System Alimentary canal (mouth, esophagus, stomach, small & large intestines, and cloaca) is where food is digested, absorbed & wastes eliminated Stomach breaks down food Pyloric sphincter muscle controls movement of food from stomach into first part of small intestine called duodenum

Digestive System Small intestine Accessory Organs: First region: duodenum Held together by mesentery Accessory Organs: Liver makes bile to digest fats stored in gall bladder Pancreas

Digestive System Wastes collect in large intestine Move into cloaca along with eggs, sperm, & urine until they leave body through the anus

Digestive System

Digestive System

Respiratory System Differs between larvae and adult Larvae: use gills and skin Adult: lungs, some skin Many salamanders have no lungs Glottis – connection between the nose and the bronchii Bronchii – connect glottis to lungs

Respiratory System

Circulatory System Need more oxygen to burn increased amount of food needed to live on land Spleen More complex circulatory system Double loop blood circulation pulmonary from heart to lungs systemic from heart to rest of body

Circulatory System 3 chamber heart Left atrium Right atrium Ventricle

Circulatory System Anterior vena cava - from anterior portion of body to heart Posterior vena cava – from posterior portion of body to heart Sinus venosus – both vena cava join to enter heart (right atrium) Blood moves from right atrium to ventricle From ventricle to lungs through the pulmonary arteries

Circulatory System Blood moves from lungs back to the heart through the pulmonary veins Pulmonary veins empty into the left atrium Left atrium pumps into ventricle. Ventricle leads to conus arteriosus Conus arteriosus – large artery leading from heart to the body

Circulatory System

Nervous System Relatively well developed Brain is larger

Nervous System Olfactory lobes Cerebrum behind olfactory lobes controls muscles Pineal Gland - produces hormones Optic lobes Cerebellum controls balance & coordination Medulla oblongata controls heart rate & breathing Cranial nerves connect brain & spinal cord, while spinal nerves branch off the spinal cord to muscles & sensory receptors

Brain of the frog

Excretory System Kidneys – separate liquid waste from blood Urinary Ducts  bladder  cloaca On the kidneys: Adrenal Gland Produces adrenaline

Reproductive System External fertilization Seasonal – spring Females lay eggs in water Males deposit sperm over eggs

Reproductive System Male: Female: Testes Seminal vesicles Ovaries Oviducts

Other adaptations Dormancy during unfavorable environmental conditions Hibernate during cold months Many fat bodies throughout abdomen for energy during hibernation

Sexual Dimorphism Physical characteristics differ between male and female “Hands” of frogs are different between male and female Male: larger “thumb” Males: vocal sacs Mating calls Show dominance

Frog Dissection

Day 1: External Anatomy

Day 1: Pre lab quiz Group assignments External anatomy of the frog Put your name on an index card I will pick 2 or 3 pieces of paper for each group The person you are picked with is your lab partner. External anatomy of the frog Sketch all external anatomy Open mouth and sketch/label After the external anatomy: frog metamorphosis activity

Growth and Development Larva Metamorphosis Adult

Day 2: Internal Anatomy

Day 2: Internal Anatomy Open up the frog and observe/sketch each system Sketch overall internal structure Be sure to notice: Digestive system Urogenital system (kidneys with reproductive organs) Respiratory structures