Unit 9 Chordates

Ch. 30 Nonvertebrate Chordates, Fishes, & Amphibians

What Is a Chordate? A chordate is an animal that has, for at

least some stage of its life, a dorsal, hollow nerve cord; a notochord; pharyngeal pouches; & a tail that extends beyond the anus

What Is a Chordate? Notochord - a long supporting rod that

runs through the body just below the nerve cord

Pharyngeal pouches - paired structures in the throat region, used to help in gas exchange

Most Chordates Are Vertebrates Vertebrae - individual segments that

make up the backbone

Nonvertebrate Chordates The 2 groups of nonvertebrate chordates

are tunicates & lancelets Both are soft-bodied marine organisms Tunicates are often called sea squirts

because of the stream of water they eject

Nonvertebrate Chordates Lancelets are small nonvertebrate

chordates that often live with their bodies 1/2 buried in sand

What Is a Fish? Fishes are aquatic vertebrates; most

fishes have paired fins, scales, & gills

Evolution of Fishes The evolution of jaws & the evolution of

paired fins were important developments during the rise of fishes

Form & Function in Fishes Adaptations to aquatic life include various

modes of feeding, specialized structures for gas exchange, & paired fins for locomotion

Groups of Fishes When you consider their basic internal

structure, all living fishes can be classified into 3 groups: jawless fishes, cartilaginous fishes, & bony fishes

Diversity of Ray-Finned Fishes

Ecology of Fishes Fishes are important source of food for

many organisms

What Is an Amphibian? An amphibian is a vertebrate that,

typically, lives in water as a larva & on land as an adult, breathes with lungs as an adult, has moist skin that contains mucous glands, & lacks scales & claws

Evolution of Amphibians Early amphibians evolved several

adaptations that helped them live at least part of their lives out of water

Bones in the limbs of amphibians became stronger, permitting more efficient movement

Evolution of Amphibians Lungs & breathing tubes enabled them to

breathe air The sternum, or breastbone, formed a

bony shield to support & protect internal organs, especially the lungs

Form & Function in Amphibians Tadpoles are filter feeders,

adult amphibians are almost entirely carnivorous

Form & Function in Amphibians An amphibian’s heart has 3 chambers, 2

atria & 1 ventricle Some wastes diffuse across the skin, but

kidneys remove most wastes from bloodstream

Form & Function in Amphibians An amphibian typically begins its life in

water, then moves on land as an adult

Groups of Amphibians The 3 groups of amphibians alive today

are salamanders, frogs & toads, & caecilians

Diversity of Amphibians

Ecology of Amphibians Some amphibians that release toxins

have brightly colored bodies The colors & patterns

serve as a warning to potential predators