Fishes and Fishes and AmphibiansAmphibians

Chapter 26-2Chapter 26-2

Characteristics of FishCharacteristics of Fish

Phylum Chordata (have a spinal cord)Phylum Chordata (have a spinal cord) Have a Have a notochordnotochord(flexible supporting rod that (flexible supporting rod that

runs along the dorsal surface of the body),runs along the dorsal surface of the body), hollow hollow dorsal nerve corddorsal nerve cord,,(on the back side of the (on the back side of the

body that conducts impulses)body that conducts impulses) and and pharyngeal pharyngeal slitsslits(structure that appears in pairs in throat region)(structure that appears in pairs in throat region)

The notochord is replaced by a The notochord is replaced by a backbone backbone ((vertebral columnvertebral column))

Definition of a fishDefinition of a fish

Aquatic vertebratesAquatic vertebrates ScalesScales FinsFins Pharyngeal slitsPharyngeal slits Some excpetions: (some fish do Some excpetions: (some fish do

not have scales)not have scales)

Groups of fishGroups of fish

Jawless (Jawless (Agnaths)Agnaths) Bony (Class Bony (Class OsteichthyesOsteichthyes)) Cartilaginous (Cartilaginous (ChondrichthyesChondrichthyes)- )-

over 97% of all living fish today over 97% of all living fish today belong to this classbelong to this class

How did fish evolve?How did fish evolve?

They are the first vertebrates to They are the first vertebrates to evolve.evolve.

First fish were jawless, body covered First fish were jawless, body covered with bony plates (540 mya)with bony plates (540 mya)

Major adaptive radiation occurred:Major adaptive radiation occurred: Jawless with little armor (extinct)Jawless with little armor (extinct) Armored but in a new form Armored but in a new form Some had jaws that advanced them in Some had jaws that advanced them in

feedingfeeding

More about evolution…More about evolution…

Jawless fish are limited to filter feedingJawless fish are limited to filter feeding Jaws can crush, nibble, and be used in Jaws can crush, nibble, and be used in

defensedefense Fish also evolved the paired pectoral fins Fish also evolved the paired pectoral fins

and pelvic fins which gave them better and pelvic fins which gave them better control of movement in water.control of movement in water.

The fins later evolved into limbs and The fins later evolved into limbs and shoulder bones of terrestrial vertebratesshoulder bones of terrestrial vertebrates

Fish AnatomyFish Anatomy

Fish have evolved many adaptations to Fish have evolved many adaptations to many environmentsmany environments

Feeding: every form of feedingFeeding: every form of feeding Sawfish kill and stun preySawfish kill and stun prey Parrotfish have teeth fused into a beak Parrotfish have teeth fused into a beak

to bite coral to bite coral Archerfish spits drops of water and Archerfish spits drops of water and

shoots down insectsshoots down insects Most fish swallow the prey wholeMost fish swallow the prey whole

DigestionDigestion

MouthMouthEsophagusEsophagusStomach Stomach (partially broken down)(partially broken down)

Pyloric cecaPyloric ceca(little pouches that (little pouches that break down food) break down food)

Intestines (complete digestion and Intestines (complete digestion and absorbtion)absorbtion)

RespirationRespiration Most use Most use gillsgills that are located on either that are located on either

side of the side of the pharynx pharynx (connects mouth to (connects mouth to digestive tract)digestive tract)

Many capillaries to increase surface area Many capillaries to increase surface area for gas exchangefor gas exchange

Water enters the mouthWater enters the mouthover the gill over the gill filamentsfilamentsslits in the sides of the pharynxslits in the sides of the pharynx

Some use the Some use the swim bladderswim bladder (organ used (organ used to control the depth of swimming) as to control the depth of swimming) as lungs (ex. Siamese fighting fish)lungs (ex. Siamese fighting fish)

Internal TransportInternal Transport Closed Circulatory SystemClosed Circulatory System Heart has Heart has 2 chambers2 chambers OO22 poor blood collects in the poor blood collects in the atriumatrium Then pumps into the Then pumps into the ventricleventricle Blood is pumped through the Blood is pumped through the aorta aorta to the to the

gillsgills Then blood is transported to the rest of the Then blood is transported to the rest of the

bodybody Collects in Collects in Sinus VenosusSinus Venosus (veins) then re- (veins) then re-

enters the atriumenters the atrium

ExcretionExcretion

Nitrogenous waste in the form of Nitrogenous waste in the form of NHNH44

Through gills in the waterThrough gills in the water KidneysKidneys filter blood filter blood Also control the amount of water in Also control the amount of water in

the body the body (salt-water fish need to keep (salt-water fish need to keep water and fresh-water fish need to get rid of water and fresh-water fish need to get rid of excess water)excess water)

ResponseResponse

Fish have a well-developed nervous Fish have a well-developed nervous systemsystem

Olfactory bulbsOlfactory bulbs and and CerebrumCerebrum at at front of head- smell (front of head- smell (chemoreceptorschemoreceptors))

Optic lobesOptic lobes- sight- sight CerebellumCerebellum-movement -movement MedullaMedulla-internal organs and balance-internal organs and balance Lateral-Lateral- line detect motion line detect motion

Internal AnatomyInternal Anatomy

ReproductionReproduction

Separate sexes- male and femaleSeparate sexes- male and female OviparousOviparous-lay eggs-lay eggs OvoviviparousOvoviviparous-eggs develop -eggs develop

within femalewithin female ViviparousViviparous- true live-bearing- true live-bearing

Jawless FishJawless Fish

No backbones, just notochordNo backbones, just notochord Lampreys-Lampreys- parasitic, large sucking parasitic, large sucking

disc at the head to latch on to preydisc at the head to latch on to prey HagfishesHagfishes-pinkish-grey wormlike -pinkish-grey wormlike

bodiesbodies No eyes, feed on dead or dying fishNo eyes, feed on dead or dying fish Secrete a lot of slime, have 6 hearts, Secrete a lot of slime, have 6 hearts,

and sometimes tie themselves in a knot!and sometimes tie themselves in a knot!

HagfishHagfish

LampreyLamprey

Sharks and RelativesSharks and Relatives

Endoskeleton made out of cartilageEndoskeleton made out of cartilage

Tough scalesTough scales

3,000 teeth3,000 teeth

Filter feeders, eat Filter feeders, eat crustaceans,molluskscrustaceans,mollusks

More people are killed by lightning More people are killed by lightning than sharksthan sharks

Sharks and RaysSharks and Rays

Bony FishBony Fish

15,000-40,000 species alive today15,000-40,000 species alive today Ray-finnedRay-finned-(thin bony spines that -(thin bony spines that

are connected by a thin layer of are connected by a thin layer of skin to form fins.)skin to form fins.)

There are many adaptations of fins There are many adaptations of fins ( poison, leaping, climbing)( poison, leaping, climbing)

Only 7 are not classified as ray-Only 7 are not classified as ray-finned fishfinned fish

LungfishLungfish

Some can use gills to eliminate COSome can use gills to eliminate CO22 and and gulp air to receive Ogulp air to receive O22

CoelacanthCoelacanth is a lobe-finned fish is a lobe-finned fish Few bones in fin basesFew bones in fin bases Probably used these in ancient times to Probably used these in ancient times to

move from pool to poolmove from pool to pool We thought they were extinct(found in We thought they were extinct(found in

1938)1938) Closest living relative to land vertebratesClosest living relative to land vertebrates

CoelacanthCoelacanth

How do fish fit into the How do fish fit into the world?world?

Important food source in many Important food source in many ecosystemsecosystems

Control population growth Control population growth (especially some plants)(especially some plants)

Recreation in tanksRecreation in tanks

AmphibiansAmphibians

Smallest groups of vertebratesSmallest groups of vertebrates Fishlike aquatic organisms that breathe Fishlike aquatic organisms that breathe

through gills, where as the adults are through gills, where as the adults are terrestrial and breathe through skin terrestrial and breathe through skin (there are exceptions)(there are exceptions)

Aquatic larvaeAquatic larvae Eggs do not have a shellEggs do not have a shell Skin has not protection Skin has not protection If skin dries out they suffocateIf skin dries out they suffocate

EvolutionEvolution

~360mya~360mya From lobe-finned fishFrom lobe-finned fish Bones became stronger for Bones became stronger for

movement on landmovement on land ScalesScales EarsEars EyelidsEyelids

Why were amphibians so Why were amphibians so successful?successful?

The land was empty of life The land was empty of life Well established plant lifeWell established plant life Arthropods were there (includes Arthropods were there (includes

insects)insects) Plenty of food and spacePlenty of food and space Many became extinct after climate Many became extinct after climate

changes changes

Form and function of Form and function of AmphibiansAmphibians

Feeding:Feeding: Larvae filter feedLarvae filter feed Tadpoles are herbivorousTadpoles are herbivorous Adults are carnivorousAdults are carnivorous Food enters Food enters

MouthMouthEsophagusEsophagusStomachStomachSmall Small intestines(food absorbed)intestines(food absorbed)Large Large intestine (absorbs water)intestine (absorbs water) CloacaCloaca (gets rid of waste)(gets rid of waste)

Internal Anatomy of FrogInternal Anatomy of Frog

Permian PeriodPermian Period

RespirationRespiration

Lungs, Mouth, SkinLungs, Mouth, Skin Skin is thin and and rich in blood Skin is thin and and rich in blood

vesselsvessels They cannot exhale and inhale like we They cannot exhale and inhale like we

do.do. Fill mouth with air and force it into Fill mouth with air and force it into

lungslungs Frogs croak by forcing air into a pair Frogs croak by forcing air into a pair

of vocal sacs in the back of the mouthof vocal sacs in the back of the mouth

Internal TransportInternal Transport

Linked to lungs in adultsLinked to lungs in adults Double loop Double loop 11stst loop carried O loop carried O22 poor blood from heart poor blood from heart

to lungs and takes Oto lungs and takes O22 rich blood from the rich blood from the heart to the rest of the bodyheart to the rest of the body

22ndnd loop takes O loop takes O22 rich blood from the heart rich blood from the heart to the rest of the body and and Oto the rest of the body and and O22 poor poor blood from the body back to the heartblood from the body back to the heart

The heartThe heart

Has Has 3 chambers3 chambers: : Left atrium, right Left atrium, right atrium and ventricle atrium and ventricle

Blood from the body enters in the vena Blood from the body enters in the vena cavacava sinus venosussinus venosus right atrium right atrium

Blood from the lungs enters the left Blood from the lungs enters the left atriumatrium

Atria contractAtria contractempty into empty into ventricleventriclebulbus cordusbulbus cordusaortic aortic arches to the rest of the bodyarches to the rest of the body

HeartHeart

ExcretionExcretion

Use kidneys to filter Nitrogenous Use kidneys to filter Nitrogenous waste from bloodwaste from blood

Urine travels through tubes called Urine travels through tubes called uretersureters into the cloaca into the cloaca

Stored in bladder or expelledStored in bladder or expelled

ResponseResponse

Well developed nervous systemWell developed nervous system Eyes can move around and are protected Eyes can move around and are protected

by a transparent by a transparent nictitating nictitating membranemembrane Can hear and sounds are used in calls for Can hear and sounds are used in calls for

matingmating Do not regulate body-tempDo not regulate body-temp They can hide, run away, produce poison, They can hide, run away, produce poison,

or use camouflage to escape predatorsor use camouflage to escape predators

ReproductionReproduction

Male climbs on back of femaleMale climbs on back of female She releases eggs in the waterShe releases eggs in the water Male fertilizes theseMale fertilizes these Surrounded by a thick jelly as they Surrounded by a thick jelly as they

developdevelop Tadpoles develop in 1-3 weeksTadpoles develop in 1-3 weeks Not all amphibian eggs are Not all amphibian eggs are

fertilized externally fertilized externally

Frog Life CycleFrog Life Cycle

SalamandersSalamanders

Keep tails as adultsKeep tails as adults Larvae and adult are carnivoresLarvae and adult are carnivores Some have gills for waterSome have gills for water Some switch and live on land and Some switch and live on land and

return to the water to breedreturn to the water to breed

Eastern Redback Eastern Redback SalamanderSalamander

Frogs and ToadsFrogs and Toads

Most live in waterMost live in water Some toads have inhabited dry Some toads have inhabited dry

land (they can burrow in soil and land (they can burrow in soil and absorb water like plants)absorb water like plants)

Many produce toxinsMany produce toxins

Poison frogsPoison frogs

How do Amphibians fit into How do Amphibians fit into the world?the world?

Prey on insectsPrey on insects Tadpoles eat a lot of algaeTadpoles eat a lot of algae Researchers are using poisons to Researchers are using poisons to

see how the nervous system workssee how the nervous system works Salamander can regenerate and Salamander can regenerate and

frogs cannot- under researchfrogs cannot- under research