BIO 202- Chapter 29 Vertebrates

What are chordates?

deuterostomes with an internal skeleton made up of bone and/or cartilage to which muscles are attached

Amniotes

Mammals, reptiles

Tetrapods

-animals with four limbs

- mammals, reptiles, amphibians

Gnathostomes

-jawed vertebrates

- Mammals, reptiles, amphibians, lobe-finned fishes, ray-finned fishes, cartilaginous fishes

vertebrates

animals with backbones

Four Characteristics shared by ALL chordates at some point in their lifetime

Notochord, dorsal hollow nerve chord, Pharyngeal pouches, post-anal tail

Notochord

- located below the nerve cord

- vertebrates have in embryo stage

- replaced by vertebral column during embryonic development

dorsal hollow nerve cord

- anterior portion becomes brain

- spinal cord protected by vertebrae

Pharyngeal pouches

- only seen in embryonic development in most vertebrates

- Becomes gills in non-vertebrate chordates, fish, and amphibian larva

Post-anal tail

- disappears in some chordates during embryonic development (example: humans)

"non-vertebrate" chordates

- Subphylum cephalochordata

- Subphylum urochordata

Subphylum Cephalochordata

- Lancelets

- Small, marine chordates that posses all four chordate characteristics

- filter feed

Subphylum Urochordata

- Tunicates (sea squirts)

- Larva are bilaterally symmetrical and posses all four chordate characteristics

- Pharyngeal gills in adults

Four Characteristics shared by ALL vertebrates at some point in their lifetime

vertebral column, skull, endoskeleton, internal organs

Vertebral column

- develops into vertebrae

- Gives rise to intervertebral discs

Skull

- encases and protects the brain

- high degree of cephalization

Endoskeleton

- bone or cartilaginous

- grows with animal, attachment for muscles

- allows for efficient movement

internal organs

- large coelom and complete digestive system

- closed circulatory system and nervous system

- efficient excretory system

- sexual reproduction most common

Development of vertebrae

- remnant tissue of notochord forms the intervertebral disks

What were the earlies vertebrates?

jawless fish

Fishes- earliest _____________ vertebrates

- Class Agnatha: ___________

- diverging

- Jawless fish

a. Hagfish

- Scavengers, secrete slime

b. Lampreys: most are filter feeders, parasitic lampreys, have round suckers

Jawed Fish Characteristics

- ectothermic, gills, cartilaginous or bony skeleton, scales

What are the classes of jawed fish?

Chrondrichthyes, Osteichthyes, Sarcopterygii

Class Chrondrichthyes

- cartilaginous fish

- Sharks, rays, skates, and chimaeras

- spiracle: opening behind eyes connected to gill chamber

- Dermal denticles: tiny teeth like structures

- Well developed senses

Class Osteichthyes

- bony fish

- Ray-finned fish: fan-shaped fins supported by thin bony rays

- lack external gill slits: covered by operculum

- swim bladder

- Well-developed nervous system with brain

- complex behavior and separate sexes (external fertilization)

Class Sarcopterygii

- lobe finned and lungfish

- Fleshy fins supported by bones

- only 2 species of lobe-finned and 6 species of lungfish

- ancestral species hypothesized to give rise to amphibians

- LUNGFISH have lungs AND gills

Shared characteristics of class amphibia.

four limbs (tetrapods), smooth and scaly skin, lungs (axolotl), double-loop circulatory system, sense organs (sight, smell, hearing), ectotherm, aquatic reproduction

What organism(s) were amphibians hypothesized to descend from?

Lobe-finned/lungfish

What are representative members of amphibians?

salamanders, newts, frogs, toads, axolotls, caecilians

Amniote characteristics

amniotic egg, impermeable skin, costal ventilation of lungs, temporal fenestration

Extraembryonic membrane of amniotes

- Amnion, allantois, and chorion

- Protection, nourishment, removes wastes, and provides oxygen and water

What are representative members of class reptilia?

snakes, turtle, crocodile, lizards, tuataras

What common ancestor do reptiles and birds share?

archosaurs

What are anatomical adaptations for fight? (aves)

- Feathers: insulation and flight

- Efficient respiratory and circulatory systems

- Modified skeleton

- Modified respiration: lungs connect to anterior and posterior air sacs

Distinguishing characteristics of mammals

- mammary glands

- hair

- skeleton: larger brain to body size than reptiles

- efficient respiratory, circulation, nervous system

- double loop circulation and 4 chambered heart

- well developed senses and complex behavior

- endothermic

- internal development of offspring

What are the three lineages of mammals?

monotremes, marsupials, placentals

Order Monotremata: monotremes

- Monotreme: one urogenital opening, the cloaca, for birth and reproductive canal

- Egg laying

Marsupials

- pouched mammals

- Kangaroos, koalas, opossum, sugar glider, wombat, tasmanian devil

Placentals (eutherians)

- most abundant mammals

- offspring develop from nourishing placenta tissue in uterus

- Placenta: specialized organ for exchange of substances between maternal blood and fetus

- extensive parental care

All of the following are ectotherms EXCEPT: ray-finned fish, amphibians, reptiles, birds

birds

Birds are descended from archosaurs

true

The two invertebrate chordates subphyla are

cephalochordata and urochordata

Amphibians are hypothesized to have descended from

lobe-finned fish

Amniotes include all of the following EXCEPT: birds, reptiles, snakes, amphibians, mammals

amphibians

Which chordate trait forms the brain and spinal cord in chordates during development?

dorsal hollow nerve chord

All of the following are traits shared by all chordates at some point in their development EXCEPT: dorsal hollow nerve cord, notochord, amniotic egg, post-anal tail, pharyngeal pouches

amniotic egg

All gnathostomes are jawed vertebrates

true

Which mammal group(s) includes only 2 species of egg-laying mammals on earth

order monotremata

Which chordate trait forms the vertebral column in chordates during development

notochord

Which group was the first group of evolving vertebrates

jawless fish