3 Classes down, 2 more to go Myxini (hagfishes) Petromyzontida (lampreys) Chondrichthyes (sharks,...
-
Upload
evan-baker -
Category
Documents
-
view
218 -
download
1
Transcript of 3 Classes down, 2 more to go Myxini (hagfishes) Petromyzontida (lampreys) Chondrichthyes (sharks,...
3 Classes down, 2 more to go
• Myxini (hagfishes)
• Petromyzontida (lampreys)
• Chondrichthyes (sharks, rays and chimaeras) – How many?
What do you think?
•Is the lancelet a fish?
Fish-like characters of lancelets-myomeres -nerve cord-post-anal tail -notochord-pharyngeal slits (gills?)
*Compare to lamprey ammocoete
Where are we?
Phylum Chordata
Lancelets- Subphylum Cephalochordata
Everything else- Subphylum Craniata
What are we?
What makes a craniate?-cranium-red blood cells-bone (or cartilage)
What makes a vertebrate?-vertebrae-dermal bones-neural crest
Hagfish vs. Lamprey
•Compare and contrast the specimens
Shark inner ear has 3 semicircular canals
How are they related?
For now, lampreys considered basal to vertebrates
But..Compelling evidence exists that supports the cyclostome hypothesis
Relationships are uncertain!
Cyclostome Hypothesis Vertebrate Hypothesis
We covered the jawless fishesWhat next?...
Jawed fishesSuperclass Gnathostomata
Class Chondrichthyes
• Subclass Holocephali (etymology?)– Chimaeras
• Subclass Elasmobranchii– Sharks– Skates and Rays
Chondrichthyan characters
• Cartilaginous skeleton• Fin “rays” called ______________• No gas bladder• Oily liver• Spiral valve intestine • Claspers • Ampullae of Lorenzini
Differences
Holocephali ElasmobranchiiJaw fused Jaw protrusibleEver-growing toothplate Serially replaced teethScaleless Placoid ScalesNo cloaca (?) Cloaca
Sharks vs. Rays
• Division Neoselachii– Subdivision Selachii – Sharks• Pectorals not fused to head• Some with anal fin• Gill slits lateral
– Subdivision Batoidea – Rays and skates• Pectorals fused to head• No anal fin• Gill slits ventral
Videos
• http://animal.discovery.com/videos/mutual-of-omahas-wild-kingdom-manta-ray-fingerprints.html
http://www.youtube.com/watch?v=rsFVDmFvRbg
Shark Lab1. What does Gnathostomata mean? And what taxonomic
level is it?2. How do you tell gender of shark, ray or chimaera?3. How do you tell a shark apart from a ray (harder than
you may think)?4. Terms (what they are and what they look like):
palatoquadrate, ceratotrichia, Ampullae of lorenzini, placoid scales
5. Know how to identify all orders (families for Myliobatiformes). Know names of representative families.
6. 2 differences between Holocephali and Elasmobranchii