week 11-tay Flashcards
how many years ago did fish evolve?
500 million years ago
what is the common ancestor for all fish/mammals?
ancestral chordates
example of uro-chordates
tunicates
example of cephalo-chordates
lancelets
first vertebrae fish
jawless fish
- no bck
cartilaginous fish
have jaws only
- no back
bony skeleton fish
bony fishes and lobe-finned fishes
lobe-finned fish
have appendages - like arms that move
lung development
frogs
development of the amniotic egg
reptiles and birds
development of mammary glands
mammals
lancelets
the closest species to the common chordate ancestor
- like living fossils - contain a notochord but no vertebrae
- benthic filter feeders
benthic filter feeder
live in (or near) ocean floor and feed by filtering small particles from the water
fish
- most abundant and diverse vertebraes
- use gils for breathing and fins for swimming
- ectothermic (mostly)
- great diversity - size, shape, speed of movement, lifestyles and habitat
ectothermic
don’t regulate body temperature - it changes with environment
what fish are not ecothermic?
some tuna and sharks can regulate their body heat to some degree with metabolism
jawless fish
- no paired appendages to aid in locomotion (get around by wiggling their tails)
- round sucking mouths
- some are parasitic (predatory)
2 types of jawless fish
- lampreys
- hagfish
parasitic function fo jawless fish
they stick their round sucking mouth into the side of a fish and chew away on it
sea lamprey
- no scales
- large eyes, one nostril on top of head
- 7 gill pores
- cartilaginous skeleton
- can adapt to both freshwater and saltwater
where can you find sea lamprey?
oceans
- they have also invaded the Great Lakes (stated in 1800’s in Lake Ontario)
hagfish
- some are predatory, but most are scavengers - no jaws, but lots of teeth
- slimy and tie themselves into knots
- body is covered in pores that secretes fibrous slime (mucus)
mucus/slime produced by hagfish
- when slime combined with water it will expand - up to 20L of slime
- used as a defence mechanism
- they tie themselves into a knot to scape off the slime
what is the slime hagfish produce composed of?
protein and mucus