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 naresTympanic membraneNictitating MembraneUpper and lower eye lidTrunkHeadForelimbHindlimb

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

Muscular System Submaxillary Control of the Forelimbs:

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

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 ventricle pumps into ventricle. Ventricle leads to truncus arteriosus Truncus 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 Females lay eggs in water Males deposit sperm over eggs

Reproductive System Male:

Testes Seminal vesicles

Female: Ovaries Oviducts

Growth and Development Larva

Metamorphosis

Adult

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