Class notes
Phylum Echinodermata
- Course
- Institution
Lecture notes on echinoderms (part of echinoderms and chordates)
[Show more]
Seller
Follow
aiswaryamenon
Content preview
Phylum EchinodermataThis is part of deuterostomia. It's divided into echinodermata and chordata.
Archenteron is an endoderm lined cavity at gastrulation that develops into a digestive tract. Coelom
is a body cavity lined with mesoderm. Blastopore is the opening in the archenteron.
Evolution of echinodermata based of the 'asterozoan hypothesis'
During the cambrian period.
Phylum echinodermata features
Adults have radial symmetry of 5
Open circulatory system, no heart
Dipleurula larvae
Slow moving or sessile
Nerves but no cephalisation
Water vascular system
They have a thin skin that covers an endoskeleton of hard calcareous plates, giving skeletal bumps
and spines with different functions.
Water vascular system is unique to echinoderms. It’s a network of hydraulic canals branching into
extensions called tube feet. These function in locomotion, feeding and gas exchange. The
madreporite is the opening of the water vascular system.
How it works is that the ampullary muscles extend and stick but the retractor muscles shorten.
Sexual reproduction in echinoderms usually involves release of gametes by separate males and
females into the seawater. Their ciliated, planktonic, dipleurula larvae are bilateral and even the
adults aren't truly radial.
Dipleurula larvae: a band of cilia encircles their mouth. The dipleurula type of larvae is only found in
echinoderms and hemichordates. The ciliated larvae of hemichordates are very similair to those of
echinoderms. This suggests that these 2 groups stem from a common ancestor. The trochophore
type of larvae found in many protostomes has a band of cilia encircling the body anterior to the
mouth.
There are 6 classes in the echinoderms:
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 aiswaryamenon. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $7.16. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
80796 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now