Group: Cyclostomes Flashcards
Define Cyclostomes
jawless fish
What do Cyclostomes lack? (4)
- jaws
- internal ossification
- scales
- paired fins
What are jawless fish’ gill openings like? What are they called?
- pore-like
- brancheophores
What are jawless fish bodies like?
- eel like
How many nostrils do jawless fish have?
1
What do hagfish lack
vertebrae
are hagfish marine or freshwater?
marine
when do hagfish regulate matter?
when environment salinity changes
Can hagfish osmoregulate?
no, they just take in water
If hagfish are not osmoregulators, what are they?
osmoconformers
What kind of vertebrae do lamprey have?
rudimentary
Are lamprey marine or freshwater?
freshwater
What is the vertebrate hypothesis?
- lamprey group with other fish
- hagfish are sister group to vertebrates
What is the Cyclostomata hypothesis?
- lamprey and hagfish form a clade - cyclostomata
What supports vertebrate hypothesis?
- most studies based on anatomy/anatomical data
Why is it questionable if hagfish are vertebrates?
- they have vertebrate at some stage of their life
What is the cyclostomata hypothesis supported by?
- molecular phylogenetics (mitochondrial DNA and rRNA)
** reject vertebrate hypothesis
Define osmoconformer
- keeps internal fluids isotonic (same salinity) as environment
