Class notes
Lecture notes Br26820 (BR26820)
- Course
- Institution
Vertebrate Zoology notes - Metazoan Phyolgeny
[Show more]
Seller
Follow
WillowShan
Content preview
Metazoan Phylogeny Chordata: Haeckel, 1874, Latin from neuter plural of Latin chordates “having a
(spinal) cord”, from chorda “cord” string”
Putnam et al. 2008, The amphioxus genome & the evolution of the chordate
karyotype
Of the living lineages, the cephalochordates diverged first, before the split
between the morphologically diverse urochordates & vertebrates
To a remarkable extent, the amphioxus genome appears to be a good
surrogate for the ancestral chordate genome
Together, the vertebrates, urochordates & lancelets (also known as
cephalochordates) constitute the phylum Chordata, descended from a last
common ancestor that lived perhaps 550 million years ago
Delsuc et al 2006, Tunicates & not cephalochordates are the closest living
relatives of vertebrates
Tunicates should therefore no longer be considered as “primitive” but rather
as derived chordates with highly specialized lifestyles & developmental modes
Non-vertebrate Chordates
Free swimming larval “tunicate” (Subphylum “Tunicata” or “Urochordata”)
Sessile adult “tunicate”
“Lancelet” or “Amphioxus” (Subphylum “Cephalochordata)
Notochord = Elastic rod tip to tail of body
Sea-squirts also known as class Ascidiacea
Ascidians are soft-bodies animals, for this reason their fossil record is almost
entirely lacking
Earliest reliable ascidians are Shankouclava shankouense from Lower
Cambrian Maotianshan Shale (South China)
2 enigmatic species from Ediacaran period with some affinity to the ascidians
– Ausia from Namibia & Burykhia from Northern Russia
About 3000 species of tunicate exist in the world’s oceans, living mostly in
shallow water
32 species of cephalochordates = <5cm fishlike marine animals
Greek “amphi” = both, “oxy” = sharp – lacks distinct head. Lancelets, or
amphioxus are small worm-like marine animals that spend most of their lives
buried in the sea floor, filter-feeding through jawless, ciliated mouths. Marine
waters of continental shelves
Latin for chord – notochord is present
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 WillowShan. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $6.76. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
75323 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now