Class notes
Bilaterians
- Course
- Institution
lecture notes on bilaterians from first year (part of bilaterians, molluscs, and arthropods)
[Show more]
Seller
Follow
aiswaryamenon
Content preview
Lecture 1: Bilaterians IDivided into protostomia and deuterostomia.
Bilaterians - Deuterostomia
These have only one plane of symmetry.
Bilateria: locomotion
Diploblasts have no locomotion along environmental gradients. Bilaterians have locomotion across
environmental gradients. This gives it an advantage in finding food, mates and avoiding predators.
The cephalization of bilaterians means that it has all of its sensory organs concentrated at the front
of its head. This creates a polarity since there's a concentration of nervous system.
Locomotion across gradients causes bilateral symmetry. Cnidarians which move across gradients
evolve a degree of bilateral symmetry.
Some species that have secondary radial symmetry are:
Echinoderm
Annelid
Bryozoa
Sessile bilaterians revert back to radial symmetry.
For locomotion, it requires muscles which contract and relax. Also needs a skeleton of some sort
(endo skeleton in vertebrates and exoskeleton in arthropods)
Bilateria have a hydrostatic skeleton that allows it to move by peristaltic.
Hydrostatic skeleton is formed when an enclosed volume of fluid is used to support and counteract
muscles. Its well suited for aquatic and damp terrestrial habitats.
Body cavities
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 $7.31. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
80461 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now