Includes: frogs, toads, salamanders, & caecilians (se sil i anz)
size range: tiny frog of Cuba 1/2 inch in length to giant salamander over 5 feet
none are marine
They are ectothermic (cold blooded) - not able to maintain a constant body temperature; body temp. varies with the temp. of the environment
3 orders based on body shape and type of limbs:
Apoda (AP uh duh) - Greek word meaning "without
contains caecilians (comes from Latin word meaning "blind"
strictly underground creatures - totally
blind as adults
wormlike - lack limbs
2. Order Caudata (kaw DAH tuh) - from Latin "having a tail"
contains: salamanders, newts, and sirens
often mistaken for lizards
largest living amphibian - Japanese giant salamander (5 ft.)
3. Order Anura (uh NOOR uh) - Greek meaning "without tail"
contains: frogs and toads
3 groups of anurans: (Genus)
A. Rana - frogs
remain near water
smooth, shiny skin that dries easily
B. Bufo - toads
strictly land dwellers (enter water only to mate)
rough, dry, warty skin
C. Hyla - tree frogs
usually smaller than frogs and toads and have enlarged, sticky discs at the end of each toe
3 functions of amphibians' skin:
1. body covering
a. secretes poisonous substances
may just taste bad
may be strong enough to burn
may be fatal
Arrow poison frog
(To be effective, the toxin must enter the bloodstream directly; digestive enzymes destroy the toxin, making it safe to consume poisoned game.)
Flips out its long sticky tongue & snatches prey.
Then it flips the tongue and insect into its mouth.
teeth: 2 sets in upper jaw
maxillary (MAK suh lehr ee)
vomerine (VO mur in)
teeth are not used to chew or bite food
function - helps to hold prey
To swallow: uses blinking eyes to help force food down the gullet
path of food:
stomach (pyloric valve)
small intestine (duodenum to ileum)
colon (large intestine)
cloaca (klo AY kuh) - the cavity which collects and stores wastes from both the colon and kidneys
two glands which are part of the frog's digestive system:
liver - largest organ in the frog
produces bile (stored in gallbladder)
mesenteries - transparent membranes that surround body organs and attach them to the body wall
4 structures which amphibians use to obtain oxygen -
(1) gills - used during the aquatic stage
(2) lungs - used by terrestrial adults
lack a rib cage and diaphragm (fill their lungs by forcing air into them by lowering the floor of its mouth and swallowing air)
(3) the lining of the adult's mouth and throat
has an abundant blood supply and can exchange gases
(4) the skin
used especially in lungless amphibians
also while an amphibian is underwater for a long period of time
skin accounts for a great part of respiration
1 ventricle (pumps blood to all parts of the body)
left atrium - oxygenated blood from lungs
right atrium - deoxygenated blood from body
dorsal aorta - largest blood vessel in the frog
vena cava - largest vein in the frog
kidneys (filter wastes and excess water and concentrate them in the form of urine)
renal arteries / renal veins
2 major divisions of the nervous system:
(1) central nervous system (CNS)
brain and spinal cord
(2) peripheral nervous system (PNS)
eyes - nictitating membrane - "third eyelid"
ear - tympanic membrane - "eardrum"
male - testes produce sperm
female - ovaries produce ova (eggs)
mating process: male crocks to attract a mate
she responds when her eggs are ripe
- in the water, the male clasps the female from behind which stimulates the
release of eggs
(Latin - "embrace")
male covers the eggs with sperm
both parents usually
abandon the eggs
some female toads lay their eggs one at a time, most toads lay them in a long
string, which they spread over plants in the water.
Frogs lay eggs in clusters, which are usually anchored to vegetation.
Some tropical species attach their eggs to the underside of leaves
growing over water. As the eggs
hatch, the tadpoles drop into the water. Even
though some species lay thousands of eggs at a time (the arrow-poison frog lays a single eg), many eggs are eaten by larger
water animals, and therefore only a few reach maturity. The eggs are hatched in 2 to 25 days, depending on the water
temperature; low temperatures slow down development.
white-lipped frog lays its eggs in a hole near a pond, then whips the
jellylike substance into a foam in which the tadpoles live until rain washes
them into the pond. The Surinam
toad of South America lays its eggs and then quickly loops around to catch
them on its back; they remain in cavities on the female's back throughout their
larval sate. The male midwife
toad of western Europe carries the eggs wound around his hind legs.
When the eggs are ready to hatch, the male toad enters water and the
tadpoles swim away. After the
female Darwin's frog lays eggs, the
male frog picks up the eggs with his tongue and carries them around in his vocal
sac, where they hatch and the young develop.
A few species lay their eggs on land under rocks, logs, or dead leaves.
These amphibians, such as the barking
frog and the cliff frog that live
on rocky cliffs in Texas, have no tadpole stage; they hatch from the eggs and
begin life as a terrestrial animal.