Summary
Summary Finals Compilation
- Course
- Institution
Compilation of Finals Topics and Lessons
[Show more]
Seller
Follow
seanleviabiera
Content preview
CHORDATAGENERAL CHARACTERISTICS
- possesses the following (for at least some period of their life cycle):
- notochord - a cartilaginous rod running underneath and supporting the nerve
cord
- dorsal nerve cord - a bundle of nerve fibers which runs down the "back" and
connects the brain with the lateral muscles and other organs
- pharyngeal slits - a series of openings that connect the inside of the throat to
the outside of the "neck", often but not always used as gills
- post-anal tail - an extension of the body past the anal opening
DISTINCT CHARACTERISTICS
, A. TRADITIONAL (based on morphological characteristics)
B. CALCICHORDATE (based on Jefferies’ Calcichordate Hypothesis)
C. MOLECULAR (DNA evidence; currently most accepted)
HEMICHORDATES CHORDATES
Pharynx with multiple gill slits
Dorsal nerve cord
SIMILARITIES Ventral blood vessel
Bilateral symmetry
Gill slits
Notochord
Stomochord (precursor Post-anal tail
DIFFERENCES to notochord) In
Mesocoelomic cord vertebrates:
Bony
PHYLUM CHORDATA
Vetulicolians
Calcichordates
Urochordates
Cephalochordates
Conodonts
,VETULICOLIANS (AND YUNNANOZOONS)
- “sausage balloons”
- knotted in the middle: bulbous sections sandwiching a flexible connection
- large mouth with strengthened rim and guts
- five circular structures: gill slits
- Early to Middle Cambrian
- From their general form, it is assumed that all vetulicolians discovered thus far
were swimming animals that spent much, if not all, of their time living in the water
column
- From their mouths, which had no features for chewing or grasping, it is
automatically assumed that they were not predators
- From their gill slits, many researchers regard the vetulicolians as being
planktivores
CALCICHORDATES
- includes stylophorans and carpoids
- asymmetrical organisms having a calcitic outer skeleton pierced by numerous
holes
- compact body portion and a long-segmented appendage
- Middle Cambrian to Middle Devonian
PROBLEMS
- morphological and phylogenetic analyses do not correspond to requirements
- much hypothesis dependent on disputed anatomical structures
- calcite skeleton of carpoids and echinoderms was lost three times on the lines of
cephalochordates, tunicates and vertebrates
, UROCHORDATES
- includes the tunicates, ascidians, and “sea squirts”
- the name tunicate derives from the cellulose-like carbohydrate material, called
the tunic, which covers the outer body of tunicates
- sessile and suspension feeders: seawater enters the inhalant siphon, through the
pharynx, atrium and exits the exhalant siphon
CEPHALOCHORDATES
- has a well-defined notochord and dorsal nerve chord, ventral blood vessel,
pharyngeal basket, post-anal tail, liver, kidney more advanced nervous system
and many genetic and molecular features unique to them and higher chordates
- represented in modern oceans by the amphioxus or lancelet
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller seanleviabiera. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $8.49. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
79223 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now