Amphibians 2
Transcript of Amphibians 2
-
8/19/2019 Amphibians 2
1/73
Amphibians
Copyright Cmassengale
-
8/19/2019 Amphibians 2
2/73
Evolution ofAmphibians
-
8/19/2019 Amphibians 2
3/73
"Amphibian" comes from theGreek meaning "both life".
Amphibians can live on waterand on land.
Scientist infer that
amphibians evolved fromlobe-finned fishes calledcrossopterygians.
-
8/19/2019 Amphibians 2
4/73
Crossopterygian
-
8/19/2019 Amphibians 2
5/73
Biologist conclude that amphibians appearedduring the late Devonian period, about 345
million years ago.
-
8/19/2019 Amphibians 2
6/73
Crossopterygians had no gills but they hadinternal nostrils and a primitive lung that
may have enabled them then to respire forperiods of time on land.
-
8/19/2019 Amphibians 2
7/73
Characteristics
of Amphibians
-
8/19/2019 Amphibians 2
8/73
Amphibians are coldblooded, !hich
means their blood temperature risesand falls !ith that of the surroundingenvironment
•
-
8/19/2019 Amphibians 2
9/73
"hey use gills, lungs, s#in, and mouth
cavity in respiration.
-
8/19/2019 Amphibians 2
10/73
"hey have moist, smooth, thin s#in !ith noscales.$eet are !ebbed and the toes lac# cla!s.
-
8/19/2019 Amphibians 2
11/73
Amphibians have many prominent characteristics that areadaptations to a life spent both on land and in !ater%
"hey change from an a&uatic larval stage to a terrestrialadultform. "his transformation is called metamorphosis
-
8/19/2019 Amphibians 2
12/73
Amphibians enter a state ofdormancy or torpor when
conditions are unfavorable.They often bury themselves inmud or leaves, emerging whenconditions are better.
-
8/19/2019 Amphibians 2
13/73
'uch states of inactivityare #no!n as #no!n as%
ibernation when it occursin the winter
!stivation when it occursin the summer
-
8/19/2019 Amphibians 2
14/73
Larvae have two-chamberedhearts; adults have three-
chambered hearts and well-developed circulation.
-
8/19/2019 Amphibians 2
15/73
Eggs lack multicellular membranes or
shells. They are usually laid in water orin a moist environment and fertilizedeternally.
-
8/19/2019 Amphibians 2
16/73
Classification ofAmphibians
-
8/19/2019 Amphibians 2
17/73
Biologists have identified about (,3)5living species of amphibians and haveclassified them into four orders
Anura #rogs $ Toads
%rodela Salamanders
Trachystoma &ud eels Apoda - 'aecillians
-
8/19/2019 Amphibians 2
18/73
$rogs and toads ma#e up the
*rder Anura +!ithout atail-.
-
8/19/2019 Amphibians 2
19/73
'alamanders and other amphibians!ith legs and tails ma#e up the*rder rodela +visible tail-.
-
8/19/2019 Amphibians 2
20/73
-
8/19/2019 Amphibians 2
21/73
.Some a(uatic amphibians )mud eels
$ sirens* belong to the +rderTrachystoma )"rough mouth"*
-
8/19/2019 Amphibians 2
22/73
'iren
-
8/19/2019 Amphibians 2
23/73
Apoda includes caecilians, atropical, burro!ing !ormli#e
amphibians that is often
/egless
-
8/19/2019 Amphibians 2
24/73
AnuranCharacteristics
-
8/19/2019 Amphibians 2
25/73
$rogs and toads comprise the
order Anura
"here are about 3,500 #no!n
species of frogs and 300 #indsof toads
"hey are found on everycontinent e1cept Antarctica
-
8/19/2019 Amphibians 2
26/73
'ome types spend their entire life inor near !ater, but others live mainly
on land and come to the !ater only tomate
-
8/19/2019 Amphibians 2
27/73
'ome frogs and toads are climbers
that d!ell in trees or burro!ers thatlive underground.
-
8/19/2019 Amphibians 2
28/73
"oads and frogs have manysimilarities in the !ay they loo#. 'omebasic differences bet!een them are%
toads have dry, !arty s#in, !hilefrogs have smooth, !et s#in.
-
8/19/2019 Amphibians 2
29/73
Both frogs and toads return to !ater to
reproduce. 2n nearly all species eggs arefertilied e1ternally. "he fertilied eggshatch into s!imming larval forms called
tadpoles
-
8/19/2019 Amphibians 2
30/73
rodelanCharacteristics
-
8/19/2019 Amphibians 2
31/73
'alamanders, typical members of the*rder rodela, have elongated
bodies, long tails, and smooth, moists#in
-
8/19/2019 Amphibians 2
32/73
Compared to the anurans, salamanders are
less able to remain on dry land, althoughsome can live in dry areas by remaininginactive during the day
-
8/19/2019 Amphibians 2
33/73
'alamander lay their eggs in!ater and li#e anurans theyhatch into s!imming larva
!alamander eggs
-
8/19/2019 Amphibians 2
34/73
*ther species can reproduce indamp land environments. Eggs laidon land hatch into miniature adult
salamanders
&arbled Salamander
-
8/19/2019 Amphibians 2
35/73
ApodanCharacteristics
-
8/19/2019 Amphibians 2
36/73
Caecilians, members of the *rderApoda, compose a highly specialied
group of tropical burro!ingamphibians
-
8/19/2019 Amphibians 2
37/73
These legless wormlike creatures average cmlong, but they can be up to .m long.
They have very small eyes and are often blind.
They eat worms and other invertebrates
-
8/19/2019 Amphibians 2
38/73
"he caecilian male deposits spermdirectly into the female, and the
female bears live young
-
8/19/2019 Amphibians 2
39/73
"rachystomaCharacteristics
-
8/19/2019 Amphibians 2
40/73
The +rder Trachystoma containsthree living species of mud eels,or sirens.
Sirens live in the eastern %nited
States and northeastern &e/ico.
-
8/19/2019 Amphibians 2
41/73
$rog E1ternalAnatomy
-
8/19/2019 Amphibians 2
42/73
The frog0s powerful hind legs are e(uallyeffective in 1umping or swimming. +n land frogssit with their hind legs folded against the body,poised to 1ump at the first sign of danger.
&ost frogs can make leapsmany times their body
length
-
8/19/2019 Amphibians 2
43/73
$rogs eyes also !or# e&ually !ell in or out
of !ater. Because the eyes bulge out fromthe head, the frog can stay submerged!hile literally #eeping an eye out for
predators
-
8/19/2019 Amphibians 2
44/73
!yelids that can blink protect the frog0s eyes from dust
and dehydration
In addition to upper and lower eyelids, a third,
transparent eyelid called a nictitating membranecovers each eyeball and joins the lower eyelid
This membrane keeps the eyelid moist and protects it when
it is under water
-
8/19/2019 Amphibians 2
45/73
$rogs have eardrums, or tympanicmembranes, !hich are circularstructures located behind each
eye
Tympanic membrane
-
8/19/2019 Amphibians 2
46/73
The frog0s thick, moist skin
serves two important functions2respiration and protectionGlands secrete mucus to keep itfrom drying up
-
8/19/2019 Amphibians 2
47/73
'ome glands secrete foultasting or
poisonous substances that protect thefrog from enemies
-
8/19/2019 Amphibians 2
48/73
'ome frogs, such as 5ylaversicolor, can change color inorder to blend !ith the
environment.'ount thenumber of
frogs in thepicture3
-
8/19/2019 Amphibians 2
49/73
$rog 2nternal
Anatomy
-
8/19/2019 Amphibians 2
50/73
'#eletal 'ystem
The frog0s spine has ninevertebrae
The cervical vertebra at theanterior end of the spine allowsneck movement that helps frogscatch prey
-
8/19/2019 Amphibians 2
51/73
'#eletal 'ystem
4osterior to thisare seven trunkvertebrae, and
then a single sacralvertebra thatsupports the hindlegs
A long, slim bonecalled the urostylee/tends from thesacral vertebra
-
8/19/2019 Amphibians 2
52/73
'#eletal 'ystem
5ones of the pectoralgirdle, which form theshoulders, connect to
the front legs They also provide the
primary protection tothe internal organs,
since the frog has noribs The pelvic girdle
connects to the hindlegs
-
8/19/2019 Amphibians 2
53/73
Digestive 'ystem
-
8/19/2019 Amphibians 2
54/73
Digestive 'ystem
&ost frogs feed on insects, and theirdigestive system is adapted to their diet
A frog0s tongue is an e/cellent insectcatcher. The frog simply flicks out itslong sticky tongue, curls it around itsprey, and pulls the insect back into itsmouth. Then the frog snaps its mouthshut and swallows.
-
8/19/2019 Amphibians 2
55/73
Digestive 'ystem#rogs have twotypes of teeththat hold on toprey. A row of
ma/illary teethline the perimeterof the upper 1aw.Two patches ofvomerine teeth
pro1ect frombones in the roofof the mouth.
-
8/19/2019 Amphibians 2
56/73
Digestive 'ystem
Sometimes the frogblinks, pulls its eyesinward, and presses themagainst the roof of its
mouth. This action helpspush the food down itsthroat
6igestion in frogs takesplace in the alimentary
canal, which includes theesophagus, stomach, smallintestine, large intestine,and cloaca
l
-
8/19/2019 Amphibians 2
57/73
Circulatory 'ystem An adaptation to the
greater o/ygen needs ofland animals is a moreefficient circulatory systemthan the fish0s two-
chambered heart. The amphibian0s three-chambered heart partiallymi/es o/ygenated withdeo/ygenated blood and
pumps the blood throughoutthe body at higherpressure than does thefish0s heart
-
8/19/2019 Amphibians 2
58/73
The left atriumreceives o/ygenatedblood from the lungs,and the right atriumreceives deo/ygenatedblood from the body.
5oth the atria emptyinto the ventricle, the
main pumping chamberof the heart. 7n the ventricle
o/ygenated anddeo/ygenated blood mi/
partially and arepumped to the lungs andthe rest of the body.
5lood to
body
6eo/ygenated
blood
from body
R
+/ygenatedblood from
lungs
-
8/19/2019 Amphibians 2
59/73
From the rightatrium the bloodenters the single
ventricle. Theventricle thencontracts, pumpingsome blood to thelungs to receiveoxygen and some tothe rest of the body.
The blood going tothe body leaves theventricle through the
conus arteriosus, alarge vessel that liesagainst the frontside of the heart
-
8/19/2019 Amphibians 2
60/73
This vessel divides into a right and a left truncusarteriosus, which immediately branch again into threearches that carry blood to various parts of the body.
6eo/ygenated blood travels in veins back to the rightatrium from the various regions of the body.
+/ygenated blood returns from the lungs to the leftatrium via the pulmonary veins
-
8/19/2019 Amphibians 2
61/73
-
8/19/2019 Amphibians 2
62/73
6espiratory
'ystemTadpoles respire, or
e/change carbon dio/ideand o/ygen, throughgills
-
8/19/2019 Amphibians 2
63/73
6espiratory
'ystemAdult frogs lose the gills butcan respire in three ways8through the lungs, through the
skin, and through the mouth.9espiration through the lungsis called pulmonary respiration.
A frog breathes by changing
the volume and pressure of airin its mouth while eitheropening or closing its nostrils
6 i t ' t
-
8/19/2019 Amphibians 2
64/73
6espiratory 'ystem
Air moves from the throat to the lungsthrough a slit-like passage called theglottis.
5ecause the frog0s lungs are small,cutaneous respiration, or respiration
through the skin in both air and water,is very important, especially duringestivation or hibernation.
+/ygen can diffuse across the lining ofthe mouth and into the blood.
#rogs use mouth breathing for only arelatively small amount of theirrespiration.
-
8/19/2019 Amphibians 2
65/73
E1cretory 'ystem %rine and wastes from the digestive system are eliminated
through the anus.
:hen a frog is in water, its permeable skin allows the water toenter its body.
#rogs that live primarily in water rid themselves of e/cesswater by e/creting a large volume of very dilute urine.
#rogs that live mainly on land conserve water by producing asmall volume of more concentrated urine.
-
8/19/2019 Amphibians 2
66/73
E1cretory 'ystem Amphibians eliminate two primary types of metabolic
waste products2carbon dio/ide from respiration andwaste compounds from the breakdown of foods.
Are the primary e/cretory organs and lie on either
side of the spine against the dorsal body wall. Thekidneys filter nitrogenous wastes from the blood
"h 7 ' t
-
8/19/2019 Amphibians 2
67/73
"he 7ervous 'ystem
The frog brain is morecomple/ than the fish brain,enabling the frog to contendwith a more varied
environment. The optic lobes, which control
vision, lie behind thecerebrum.
The cerebellum, a small bandof tissue lying at right anglesto the long a/is of the brain,is the center of balance andcoordination.
7 ' t
-
8/19/2019 Amphibians 2
68/73
7ervous 'ystem
The medulla oblongata lies at the backof the brain and 1oins the spinal cord.7t controls organ functions.
Ten pairs of cranial nerves e/tend outdirectly from the brain. The spinal cord transmits signals from
all parts of the body to the brain andfrom the brain back to the body.
The spinal nerves branch from thespinal cord to various parts of thebody.
6 d ti ' t
-
8/19/2019 Amphibians 2
69/73
6eproductive 'ystem
5oth male and female frogs haveinternal se/ organs
The male frog0s foreleg musclesand first fingers swell
These swellings help the malemaintain his grasp on the female The reproductive system of the
male frog includes two bean-shapedcreamy white or yellowish testeslocated near the kidneys
Sperm cells develop in the testesand pass through tubes to thekidneys and urinary ducts &ale System
6 d ti ' t
-
8/19/2019 Amphibians 2
70/73
6eproductive 'ystem #emale frogs a pair of large,
lobed ovaries containing thousands of tiny immature eggslie near the kidneys
6uring the breeding seasoneggs enlarge, mature, andburst through the thinovarian walls into the bodycavity.
They remain in structurescalled ovisacs until ovulationis complete and then leave
the body through thecloacae opening.
#emale System
6 d ti ' t
-
8/19/2019 Amphibians 2
71/73
6eproductive 'ystem
The vast ma1ority of eggsand tadpoles are eaten bypredators such as fish,
birds, snakes, and turtles.Some species of frogshave
The vast ma1ority of eggsand tadpoles are eaten bypredators such as fish,birds, snakes, and turtles. Ample/us
8 t h sis
http://www.student.loretto.org/zoology/imgres
-
8/19/2019 Amphibians 2
72/73
8etamorphosis
;ewly hatched tadpoles live off yolk stored in theirbodies. They gradually grow larger and develop threepairs of gills.
Tadpoles have a two-chambered heart. Tadpoles can also
regenerate in1ured or lost body parts such as a leg ortail.
-
8/19/2019 Amphibians 2
73/73
8etamorphosis
The mouth broadens, developingteeth and 1aws. A saclike bladderin the throat divides into two sacsthat become lungs. The heart
develops a third chamber. A hormone called thyro/in
circulates throughout thebloodstream and stimulatesmetamorphosis.
The cells of the tadpole aregenetically programmed to respondto thyro/in at the appropriatestage of development.