Fish and amphibians notes

CHAPTER 30

Fish and Amphibians

SECTION 2

Fish

What is a Fish?

Aquatic vertebratesMost have paired fins for movement, scales

for protection, and gills for exchanging gases

Evolution of Fish

First Fish (510 mya) – jawless with armored bodies

The Age of Fish (505 – 410 mya) – evolution of jaws and paired fins

The Rise of Modern Fish Two major groups that live today

Fish with skeletons made of cartilage Fish with skeletons made of true bone

Form and Function in Fish

Feeding Every mode of feeding is seen in fish Some fish exhibit more than one type of feeding Food is digested internally

Mouth

Esophagus Stomach


Respiration Most exchange gases using gills

Gills


Circulation Closed circulatory system that pumps blood in a single

loop around the body


Excretion Fish eliminate nitrogen waste in the form of ammonia Some wastes diffuse through the gills and others

through the kidneysKidney


Response Well developed nervous systems organized around a

brain Fish that are active during the day have well

developed eyes Brain


Movement Many bony fish have a gas filled swim bladder that

allows them to adjust their buoyancy Move by contracting muscles on either side of the

backboneSwim bladder


Reproduction Eggs fertilized either internally or externally,

depending on the species Oviparous – eggs hatch outside the mother’s body Oviviparous – eggs stay inside the mother’s body Viviparous – embryos stay inside the mother’s body

Groups of Fish

Groups of Fish Jawless fish Cartilaginous fish Bony fish

Jawless Fish

No true teeth or jawsSkeletons are made of fibers and cartilageLack vertebrae, keep their notochords as

adultsTwo classes: lampreys and hagfish

Sharks and their Relatives

Class Chondrichthyes contains sharks, rays, skates, sawfishes, and chimaeras

Skeletons built entirely of cartilage

Bony Fish

Class OsteichthyesSkeletons made of boneAlmost all are ray- finned fish

Ecology of Fish

Most fish spend their entire lives in either fresh or salt water

Some migrate to breed Anadromous – live in

salt water but migrate to freshwater to breed (Ex: salmon)

Catadromous – live in freshwater but migrate to saltwater to breed (Ex: North American Eels)

SECTION 3

Amphibians

What is an amphibian?

An amphibian is a vertebrate that, with some exceptions: lives in water as a larva and on land as an adult breathes with lungs as an adult has moist skin that contains mucous glands lacks scales and claws

Evolution of Amphibians

The first amphibians appeared in the late Devonian Period, about 360 million years ago

The transition from water to land required that the terrestrial vertebrates had to:• breathe air• protect themselves and their eggs from drying out• support themselves against the pull of gravity

Amphibian Adaptations

Pelvic Girdle

Lungs

Leg Bones: The legs of a land vertebrate must be strong enough to hold its weight.

Skin: The skin and the lining of the mouth cavity of many adult amphibians are thin and richly supplied with blood vessels. Watery mucus is secreted by glands in the skin.

Form and Function in Amphibians

FeedingTadpoles – filter

feeders or herbivores that graze on algae

Adults – almost entirely carnivorous

Stomach

Esophagus Mouth


RespirationLarval amphibians – gas exchange through

skin and gillsAdults – usually gas exchange occurs through

lungs

CirculationCirculatory system forms a double loop

circulating oxygen-rich and oxygen-poor blood throughout the body


Right atrium

Left atrium

Ventricle

From Body

To body, lungs and skin

To body, lungs and skin From

Lungs

Heart

Lung

Kidney

Ureter

Cloaca

Urinary bladder


ExcretionKidneys filter wastes from bloodUrine exits through the cloaca

ReproductionMost species, male fertilizes egg externally in

waterSome fertilize eggs internallyMost abandon their eggs after laying them, but

a few take care of their young

Frog Metamorphosis


MovementLarva wiggle their bodies to moveAdults have 4 limbs to walk, run, or jump

ResponseWell developed nervous systems

Nictitating membrane helps keep eyes moist Tympanic membranes allow them to hear Lateral line helps to sense water movement

A Frog’s Sense Organs

Groups of Amphibians

Three groups: Salamanders Frogs and toads Caecilians

Salamanders

Long bodies and tailsMost have four legsAdults and larvae are carnivoresAdults live in moist woods where they tunnel

under rocks and rotting logs

Frogs and Toads

Frogs and toads have the ability to jumpFrogs tend to have long legs and make

lengthy jumpsToads have relatively short legs and are

limited to short hopsFrogs are more closely tied to water

Caecilians

Legless animals that live in water or burrow in moist soil or sediment

Feed on small invertebrates such as termitesMany have fishlike scales embedded in their

skin

Ecology of Amphibians

The global amphibian population is decliningIt is possible that amphibians are susceptible

to a wide variety of environmental threats

Fish and amphibians notes

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