18 Flashcards
How many species approx of fish?
30,000
The synapomorphies that group fish? 2*
*Gills arches,
*Paired Lateral fins
The fish that tetrapods and modern animals evolved from?
Lobe-finned Fish
Chordates synapomorphies? 3*
Synapomorphies:
*Notochord (a rod that runs the length of the body)
*Post-anal tail: an extension of the body that propels the animal forward
*Dorsal hollow nerve cord: since we are deuterostomes, our nervous system runs along the dorsal part of the body. The spinal fluid moving inside the ventricles of the brain.
Notochord?
Helps resist compression and aids in propulsion. It can’t be compressed. This allows it to contract the muscles around it and move the tail side to side. Without a stuff notochord, the tail will be pushed to the head.
!!!Dorsal hollow nerve cord (DHNC)?
Derives from ectoderm that rolls into a hollow tube during development. In Chordates, it is located dorsally to the notochord.
!!!How does DHNC develops?
When it is time to make DHNC, the dorsal ectoderm
Taxons within Chordates?
*Chephalochordate
*Urochordates
Chephalochordates?
Filter feeders, have gill arches that eventually evolve into jaws later in the tree of life. Post anal tail moving via alternating contractions of left and right body muscles.
!Urochordates?
Have a notochord, DHNC, and post-anal tail. However later in life, they undergo metamorphosis.
Two clades within vertebrates?
*Jaw-less fish called cyclostomes
*Gnathostomes
!!!Lampreys?
Jawless
Hagfish?
Jawless cyclostomes: eat mostly dead fish, no paired-lateral fins
Gnathostomes jaws evolve from?
Pharyngeal gills
Chondrichthyans?
cartilage which defines this group of sharks. Males also have claspers on their pelvis.
Osteichthyes?
Bone which defines this group of bony fish including ray-finned fish.
Ray-finned fish?
Bony rays that support their fins.L
Lobe-finned vertebrates?
Unique structure to their fins. A single large bone that attaches the limb to the body. It gives this lobe finned property.
Coelacanths?
Thought extinct 65Mya until 1938.
Lungfish?
Sister to tetrapods, and can breathe in air and water.