Amphibians
Dec 24, 2015
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
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 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:
Testes Seminal vesicles
Female: 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
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