Exam 1 Flashcards
(246 cards)
What is the most diverse species?
fishes
How old are the first vertebrates in the fossil record?
500 million years old
Why does similarity often occur among vertebrates?
“relatedness”
Is convergent evolution ancestry or relatedness? If not what is it?
it is not ancestry or relatedness, it is just a convergence of physical characteristics over time
How does diversity occur among vertebrates?
adaptation
Define extinct.
past organisms, no longer alive
Define extant.
present organisms, still living
What phylum are all vertebrates members of?
the phylum Chordata
What is the general definition of vertebrates?
animals with backbones
What are the 5 general groups of vertebrates?
fishes
amphibians
reptiles
birds
mammals
What is an example of “lower vertebrate” or “primitive” vertebrates?
fishes
What is an example of “higher vertebrate” or “advanced” vertebrates?
mammals
How were vertebrates classified in the older, traditional classification system?
kingdom; Animalia
phylum; Chordata
subphylum; Vertebrata
What are the 4 basic characteristics of chordates that distinguish them from other phyla?
notochord
dorsal nerve cord
pharyngeal gill slits
postanal tail
True or False. The spinal cord in humans in homologous with the notochord.
false
Is the notochord the vertebral column?
no, it is a rod like structure
What are some characteristics of the notochord?
consists of a semi-rigid group of cells surrounded by fibrous and elastic sheaths
muscles can act on it
allows for undulating body movements
Where does the notochord lie?
ventral to the “dorsal nerve cord”
Is the notochord present during embryonic development in all vertebrates?
yes
What are some examples of primitive vertebrates that the notochord remains in throughout their life?
hagfish and lampreys
In most vertebrates what is the notochord replaced with?
the vertebral column which forms around the notochord
What is the advantage of a stiff notochord in the body?
allows the side to side fish like movement
What is considered the most primitive living vertebrate?
hagfish
What forms the neural plate?
dorsal tubular nerve cord