Download Characteristics of Amphibians

Characteristics
of Amphibians
EXTERNAL COVERING
•
The skin of an amphibian serves two
important functions—
1. Respiration
2. Protection
•
The skin is moist and permeable to
gases and water
EXTERNAL COVERING
• Numerous mucous glands supply a
lubricant that keeps the skin moist
• Because of their skin, amphibians are
vulnerable to dehydration
INTERNAL ANATOMY
• Must rely on the support
of their strong internal
skeleton
• Weight is transferred or
distributed to strong limbs
that support the body
THE CIRCULATORY SYSTEM
• The circulatory system of an amphibian is
divided into two separate loops
1. Pulmonary Circulation  carries
deoxygenated blood from the heart to the
lungs, then returns the oxygenated blood to
the heart
•
The circulatory system of an amphibian
is divided into two separate loops
2. Systemic Circulation carries oxygenated
blood from the heart to the muscles and
organs of the body and brings deoxygenated
blood back to the heart
THE CIRCULATORY SYSTEM
THE CIRCULATORY SYSTEM
• This pattern of circulation provides a
significant advantage over the “singleloop” circulation of a fish—faster blood
flow to the body. In a fish, the blood loses
some of its force as it passes through the
narrow capillaries of the gills, and blood
flow slows as a result.
RESPIRATION
• Larval amphibians exchange carbon
dioxide and oxygen through their gills and
skin
• Most adult amphibians respire through the
lungs and through the skin (cutaneous
respiration)
RESPIRATION
• A frog breathes by changing the volume
and pressure of air in its mouth while
either opening or closing its nostrils
• This is called positive-pressure breathing
DIGESTIVE SYSTEM
• All adult amphibians
are carnivorous
• The amphibian
digestive system
includes the pharynx,
esophagus, stomach,
liver, gallbladder,
small intestine, large
intestine, and cloaca
EXCRETORY SYSTEM
• The kidneys are the primary excretory
organ
• Like the larvae of fishes, most amphibian
larvae excrete the nitrogen-containing
wastes as ammonia
• Adult amphibians excrete urea
NERVOUS SYSTEM
• An amphibian’s brain is about
the same size as that of a
similarly sized fish.
• The amphibian brain consists
of the cerebrum, the
cerebellum, and the medulla
oblongata
• The spinal cord and nerves
are also a part of the
amphibian’s nervous system
SENSE ORGANS
• The senses of smell,
sight, and hearing are
well developed in most
amphibians
• All amphibians have
eyes, and visual
information is often
important in hunting
and in avoiding
predators.