Diversity of Fish and Amphibians

Jeremiah was a bullfrog…..Joy to the fishes in the deep blue

sea……

Vertebrates

Phylum Chordata-named for a structure that is found in all chordate embryos

Characteristics of Vertebrates

Notochord

Hollow nerve cord along the dorsal (back) side

Pharyngeal slits

Tail that extends beyond the anus.

4 Characteristics of Vertebrates

Notochord-flexible rod that extends through much of the length of the body

Hollow nerve chord-develops into the brain and the spinal chord, non-chordates have either no nerve chord or a solid nerve cord along the ventral side (front)

Characteristics of Vertebrates

Pharyngeal gill slits- some keep them and use them for gills and when they aren’t used, they develop into jaw support, hearing and other functions

Two Groups of Invertebrate Chordates

Tunicates or sea squirts are marine animals that are sessile and filter seawater through their pharyngeal slits.

Adults only have 1 of the 4 chordate features but the larva have all 4 features.

Lancelets are blade-like chordates that resemble tunicate larva and have all four characteristics.

Tunicates

Lancelets

Vocab

Vertebrae-enclosed nerve cord, composes the backbone

Endoskeleton-skeleton inside the body, come are made of bone or cartilage, it has living cells that grow and get larger unlike arthropod skeletons that are molted.

VertebratesAlmost all vertebrates have a hinged jaw which enable the vertebrate to capture and eat prey.Hagfish and lampreys are most closely related to ancestral vertebrates because they are aquatic and lack hinged jaws and paired limbs.Hagfish are further primitive because they lack a vertebrae but are supported by an adult version of a notochord.Hinged jaws are believed to involved from skeletal supports of pharyngeal gill slits.

Class Agnatha (Jawless Fishes)

Lamprey

Class Agnatha (Jawless Fishes)

Hagfish

Tetrapods

Tetrapods-4 footed, 2 sets of paired limbs for support, some tetrapods have no limbs but evolved from limbed ancestors

Class ChrondrichthyesNearly all sharks live I marine habitats except the bull shark which can live in freshwater.Fins are not very movable so sharks aren’t very maneuverable.Continual swimming is necessary to keep from sinking but sometimes they rest on the sea floor and use their jaw muscles to pump water over their gills.Sharks also have a sensitive lateral line system which is a row of sensory organs running along the side of their body.Sharks can also detect electric fields and track prey this way.Sharks also have skin made of denticles which are like small teeth.

Class Chondricthyes (cartilaginous fishes)

sharks

Rays and Skates

Rays and skates are closely sharks but are adapted to a very different lifestyle.Rays and skates are bottom dwellers that feed on the ocean floor or cruise the open ocean feeding on plankton.Front fins are enlarged and help the animal “fly” through the water like a bird.Many rays have poisonous barbs on their tails for defense.The largest rays are the manta rays.

Class Chondricthyes

Rays

Class Chondricthyes

Skates

Class Chondricthyes

The chimera, a living fossil!

Bony Fishes

Bony fish are divided into 3 classes.All bony fish have a relatively stiff skeleton reinforced by hard calcium compounds.On each side of the head of bony fish, a protective flap called the operculum covers a chamber housing the gills and allows water to pump even though the fish isn’t moving.Bony fish also have a lateral line system and flattened stiff scales to cover the skin and glands to secrete a slimy mucus to help fish glide easily through the water.

Bony fish

There are two key features bony fish have.Bony fish have air sacs and a 2 chambered heart.A swim bladder is an air sac that functions in making the fish more buoyant and aids in hearing.The 2 chambered heart is not very efficient but works for fish because they have a slow metabolism.It is a single circuit pathway for blood flow that delivers oxygen to tissues very slowly.

Strange fish from the ray-finned fish family

Ray-finned fish

There are more than 20,000 species of these fish.

They are named for the thin flexible fins supported by bony rays or spines and these fish also have a swim bladder.

Lobe-finned fish: The coelacanth

Lobe-finned fishes

Have muscular fins supported by stout bones and are not common today and are known mainly from the fossil record.

The only surviving group is the coelacanths of Madagascar and Indonesia. (Once believed to be extinct.)

Lungfish

Lungfish

Lungfishes are found on continents in the southern hemisphere.The air bladder functions as a lung so it can breathe out of water.Lungfish also have gills to take oxygen from water.Current research indicates the lungfish may be closely related to tetrapods.

Origin of Tetrapods

Amphibians are tetrapods and were the first vertebrates with adaptations for living on land.

The earliest tetrapods lived in shallow, aquatic habitats about 400-350 million years ago during the Devonian period.

Acanthostega was an early tetrapod that had limbs like those found in reptiles and mammals including humans.

The Origin of TetrapodsAmphibians live part of their life cycle in water and part on land.The larval stage is in water while the adult stage is terrestrial.Many adults have lungs, smooth moist skin and lack scales.Tadpoles are legless larva that have gills, a lateral line system and a long finned tail like fish.There is great diversity and some amphibians have poison glands that aid in defense.An amphibian heart has a 3 chambered which is more efficient than a 2 chambered heart of a fish.

Frogs and Toads (Order Anura)

4,200 known speciesBulging eyesPair of external eardrum called a typanumWebbed feetNo tailStrong hind legsSmooth moist skinLoud mating callsToad is a term generally used for frogs that have rough skin and live in terrestrial environments

Frogs and Toads

Salamanders and Newts (Order Urodela)

500 species

Have a tail

Closely related to each other

Bodies are long and slender

Resembled early tetrapods

Some terrestrial species do not have lungs but exchange oxygen and carbon dioxide through their skin and mouth lining

Salamanders and Newts

Salamanders and Newts

American Hellbender

Japanese Giant Salamander

Caecilians (Order Apoda)

150 speciesLeglessNearly blindInhabit burrowsEvolved from a legged ancestorA few South American species have adapted to freshwater ponds and streams

Caecilians

Chordates

Vertebrate Invertebrate

4 characteristics Tunicates Lancelets

larvanotochord

Hollow nerve cord dorsal side

Pharyngeal slits

Tail that extend beyond the anus

Fish

Class ChondrichthyesBony fish

Skeleton hardenedWith calcium

Class Chondrichthyes

Sharks and rays

Cartilaginous skeleton

Bony fish

Ray-finned fish Lobe-finned fish Lungfish

Class Actinopterygii

Class Actinista Class Dipnoi

Most fish types coelocanthsAncestors to

tetrapods

Can breathe air

Amphibians

Order Anura Order Urodela Order Apoda

Order Anura

Frogs Toads

jump walk

Moist skin Rough, dry skin

Partially aquatic Usually terrestrial

Poison glands

Order Urodela

salamanders Newts

terrestrial aquatic

tail tail

Sometimes have External gills

Order Apoda

caecilians

legless

tropical