What is gastrulation?
When the blastula turns into a gastrula and forms a multilayer structure.
Where is the first opening of the gastrocoel?
The anus.
What is neurulation?
The formation of the neural tube.
Why are early vertebrates fossils not preserved well?
Because they had soft bodies.
What are extant species?
Species that are still living.
How many years were conodonts around for?
300 million.
Where do hagfishes live?
The bottom of the ocean.
What are the chondrichthyes?
Sharks and rays.
What are osteichthyes?
Bony fishes.
What is the space called in a single cell?
Blastocoel.
What is the gastrocoel/archenteron?
The early gut.
What does the ectoderm make?
The nervous system, eyes and epidermis.
What does the endoderm make?
The liver, pancreas and urinary bladder.
What does the mesoderm make?
The dermis, bones, muscles, kidneys and gonads.
When did early vertebrates emerge?
~540 million years ago.
what makes a fish a fish?
They’re non-tetrapod craniates and they have gills and fins lacking digits.
What are agnathas?
Jawless vertebrates.
What are gnathostomatas?
Jawed vertebrates.
Do agnathas have mouths?
Yes, but they can’t bite.
What are the two extant groups of agnathas?
Hagfishes and lampreys.
What is an extinct group of agnathas?
Conodonts.
What are ostracoderms?
Small, jawless fishes with a lateral line system.
How many species of lampreys (petromyzontidas) are there?
~44 species.
What are some characteristics of lampreys (petromyzontidas)?
Metamorphosize from ammocoete larva, no jaws; single nostril, cartlaginous skull and vertabrae, and image-forming eyes.
