Transcript Fishes and Amphibians Powerpoint

Fishes and
Amphibians
Chapter 26-2
Characteristics of Fish
Phylum Chordata (have a spinal cord)
 Have a notochord(flexible supporting rod that runs
along the dorsal surface of the body), hollow dorsal
nerve cord,(on the back side of the body that conducts
impulses) and pharyngeal slits(structure that
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appears in pairs in throat region)
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The notochord is replaced by a backbone
(vertebral column)
Definition of a fish
Aquatic vertebrates
 Scales
 Fins
 Pharyngeal slits
 Some excpetions: (some fish do not
have scales)
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Groups of fish
Jawless (Agnaths)
 Bony (Class Osteichthyes)
 Cartilaginous (Chondrichthyes)- over
97% of all living fish today belong to
this class
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How did fish evolve?
They are the first vertebrates to evolve.
 First fish were jawless, body covered
with bony plates (540 mya)
 Major adaptive radiation occurred:
 Jawless with little armor (extinct)
 Armored but in a new form
 Some had jaws that advanced them in
feeding
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More about evolution…
Jawless fish are limited to filter feeding
 Jaws can crush, nibble, and be used in
defense
 Fish also evolved the paired pectoral fins and
pelvic fins which gave them better control of
movement in water.
 The fins later evolved into limbs and shoulder
bones of terrestrial vertebrates
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Fish Anatomy
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Fish have evolved many adaptations to many
environments
Feeding: every form of feeding
Sawfish kill and stun prey
Parrotfish have teeth fused into a beak to
bite coral
Archerfish spits drops of water and shoots
down insects
Most fish swallow the prey whole
Digestion
MouthEsophagusStomach (partially
broken down)
 Pyloric ceca(little pouches that break
down food)
 Intestines (complete digestion and
absorbtion)
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Respiration
Most use gills that are located on either side
of the pharynx (connects mouth to digestive
tract)
 Many capillaries to increase surface area for
gas exchange
 Water enters the mouthover the gill
filamentsslits in the sides of the pharynx
 Some use the swim bladder (organ used to
control the depth of swimming) as lungs (ex.
Siamese fighting fish)
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Internal Transport
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Closed Circulatory System
Heart has 2 chambers
O2 poor blood collects in the atrium
Then pumps into the ventricle
Blood is pumped through the aorta to the
gills
Then blood is transported to the rest of the
body
Collects in Sinus Venosus (veins) then reenters the atrium
Excretion
Nitrogenous waste in the form of NH4
 Through gills in the water
 Kidneys filter blood
 Also control the amount of water in the
body (salt-water fish need to keep water and fresh
water fish need to get rid of excess water)
Response
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Fish have a well-developed nervous system
Olfactory bulbs and Cerebrum at front of
head- smell (chemoreceptors)
Optic lobes- sight
Cerebellum-movement
Medulla-internal organs and balance
Lateral- line detect motion
Internal Anatomy
Reproduction
Separate sexes- male and female
 Oviparous-lay eggs
 Ovoviviparous-eggs develop within
female
 Viviparous- true live-bearing
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Jawless Fish
No backbones, just notochord
 Lampreys- parasitic, large sucking disc
at the head to latch on to prey
 Hagfishes-pinkish-grey wormlike
bodies
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No eyes, feed on dead or dying fish
 Secrete a lot of slime, have 6 hearts, and
sometimes tie themselves in a knot!
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Hagfish
Lamprey
Sharks and Relatives
Endoskeleton made out of cartilage
Tough scales
3,000 teeth
Filter feeders, eat crustaceans,mollusks
More people are killed by lightning than
sharks
Sharks and Rays
Bony Fish
15,000-40,000 species alive today
 Ray-finned-(thin bony spines that are
connected by a thin layer of skin to
form fins.)
 There are many adaptations of fins (
poison, leaping, climbing)
 Only 7 are not classified as ray-finned
fish
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Lungfish
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Some can use gills to eliminate CO2 and gulp
air to receive O2
Coelacanth is a lobe-finned fish
Few bones in fin bases
Probably used these in ancient times to move
from pool to pool
We thought they were extinct(found in 1938)
Closest living relative to land vertebrates
Coelacanth
How do fish fit into the world?
Important food source in many
ecosystems
 Control population growth (especially
some plants)
 Recreation in tanks
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Amphibians
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Smallest groups of vertebrates
Fishlike aquatic organisms that breathe
through gills, where as the adults are
terrestrial and breathe through skin (there
are exceptions)
Aquatic larvae
Eggs do not have a shell
Skin has not protection
If skin dries out they suffocate
Evolution
~360mya
 From lobe-finned fish
 Bones became stronger for movement
on land
 Scales
 Ears
 Eyelids
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Why were amphibians so
successful?
The land was empty of life
 Well established plant life
 Arthropods were there (includes
insects)
 Plenty of food and space
 Many became extinct after climate
changes
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Form and function of
Amphibians
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Feeding:
Larvae filter feed
Tadpoles are herbivorous
Adults are carnivorous
Food enters
MouthEsophagusStomachSmall
intestines(food absorbed)Large intestine
(absorbs water) Cloaca (gets rid of waste)
Internal Anatomy of Frog
Permian Period
Respiration
Lungs, Mouth, Skin
 Skin is thin and and rich in blood
vessels
 They cannot exhale and inhale like we
do.
 Fill mouth with air and force it into
lungs
 Frogs croak by forcing air into a pair of
vocal sacs in the back of the mouth
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Internal Transport
Linked to lungs in adults
 Double loop
 1st loop carried O2 poor blood from heart to
lungs and takes O2 rich blood from the heart
to the rest of the body
 2nd loop takes O2 rich blood from the heart to
the rest of the body and and O2 poor blood
from the body back to the heart
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The heart
Has 3 chambers: Left atrium, right
atrium and ventricle
 Blood from the body enters in the vena
cava sinus venosus right atrium
 Blood from the lungs enters the left atrium
 Atria contractempty into ventriclebulbus
cordusaortic arches to the rest of the body
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Heart
Excretion
Use kidneys to filter Nitrogenous waste
from blood
 Urine travels through tubes called
ureters into the cloaca
 Stored in bladder or expelled
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Response
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Well developed nervous system
Eyes can move around and are protected by
a transparent nictitating membrane
Can hear and sounds are used in calls for
mating
Do not regulate body-temp
They can hide, run away, produce poison, or
use camouflage to escape predators
Reproduction
Male climbs on back of female
 She releases eggs in the water
 Male fertilizes these
 Surrounded by a thick jelly as they
develop
 Tadpoles develop in 1-3 weeks
 Not all amphibian eggs are fertilized
externally
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Frog Life Cycle
Salamanders
Keep tails as adults
 Larvae and adult are carnivores
 Some have gills for water
 Some switch and live on land and
return to the water to breed
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Eastern Redback Salamander
Frogs and Toads
Most live in water
 Some toads have inhabited dry land
(they can burrow in soil and absorb
water like plants)
 Many produce toxins
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Poison frogs
How do Amphibians fit into
the world?
Prey on insects
 Tadpoles eat a lot of algae
 Researchers are using poisons to see
how the nervous system works
 Salamander can regenerate and frogs
cannot- under research
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