100% satisfaction guarantee Immediately available after payment Both online and in PDF No strings attached
logo-home
Previously searched by you
Previously searched by you
logo
Invertebrates Lecture 2 Notes - Platyhelminthes, molluscs and annelids $6.95
Add to cart
Quickly navigate to
Preview
  2.  
  3. University Of Leicester (LE)
  4.  
  5. University Of Leicester (BS1070)

Class notes

Invertebrates Lecture 2 Notes - Platyhelminthes, molluscs and annelids
 0 purchase
  • Course
  • University Of Leicester (BS1070)
  • Institution
  • University Of Leicester (LE)

Detailed and concise FIRST CLASS notes which are easy to understand and learn from, covering the second lecture of Invertebrate Zoology in the BS1070 module.

Preview 2 out of 6  pages

Document information

  • July 11, 2024
  • 6
  • 2023/2024
  • Class notes
  • N/a
  • All classes

Subjects

  • platyhelminthes
  • molluscs
  • annelids
  • lophotrochozoa
  • planarians
  • endoparasites
  • lophophorata
  • trochozoa
  • gastropoda
  • torsion
  • bivalvia
  • cephalopods
  • hydrostatic skeleton
  • organ systems
  • earthworms
  • leaches

Written for

  • University of Leicester (LE)
  • Unknown
  • University Of Leicester (BS1070)
All documents for this subject (3)

Seller

avatar-seller
elishakaur

Content preview

University of Leicester - BS1070 - Week 4 - Adaption and diversity


Invertebrates - Lecture 2: Platyhelminthes, Molluscs and Annelids

Bilaterian phylogeny
- Bilaterally symmetrical (one symmetrical axis) organisms with a mesoderm (triploblastic)
- Traditional bilateral phyla are defined by cleavage patterns, mesoderm formation and coelom
- These do not necessarily reflect phylogenetic relationships
- Molecular phylogeny is based on sequence similarities (e.g. 18S ribosomal RNA)
- Indicates relatedness
- Phylogenetics determined protostomes and deuterostomes
- Protostome: mouth forms before the anus e.g. flatworms, annelids, arthropods
- Deuterostomes: mouth forms after the anus e.g. humans, tigers, monkeys


Lophotrochozoa
One of two main protostome clades
- Very diverse assemblage of morphologically disparate phyla
- Typically with spiral cleavage
- Unites two major groupings (clades)
- Lophophorata
- Trochozoa
- And the platyhelminthes

Platyhelminthes
Bilateria without a coelom - 20 000 species today

Planarians
- Free living non-parasitic
flatworms
- Mostly predators, creep
with ciliated epidermis
(smaller) OR crawl with
muscular wave (larger)
- Have a head with
eye-spots and brain
- Have a mouth on ventral
surface, half way down
the belly side
- Flatworms have bilateral symmetry
- Have a distinct head and tail end
- Distinct dorsal and ventral surfaces
- They are mesodermal, therefore triploblastic
- Have tissues and organs → CNS: brain and longitudinal nerve cords

, University of Leicester - BS1070 - Week 4 - Adaption and diversity



- Planarians do not have an anus
- Eat and excrete out of their mouth
- Acoelomates: no body cavity
- Mesodermal mesenchymal fills entire space between endoderm and ectoderm
- No circulatory or respiratory organs
- Simple diffusion of gases through their body surface
- Thin and long, increases surface area
- Gut forms a gastrovascular system

Planarians - reproduction
- Sexual hermaphrodites (male and female gametes)
- Also asexually reproduce via spontaneous fissions
- Experiment and accidental regeneration
- Can be cut up lengthwise or across, each piece will degenerate into the complete animal

Parasitic platyhelminthes (endoparasites)
- Trematoda (flukes): tissue parasites - blood, liver and lungs
- Cestoda (tapeworms): gut parasites
- Consequences of living indies the gits of another organism:
- Needs for resistant covering to protect against host’s digestive enzymes → loss of cilia
- Surrounded by food, no directional external threats → reduction of nervous system, loss
of cephalisation
- Don’t need a gut for yourself → loss of gut, direct absorption through microvilli on body
surface

Lophophorata
- Filter feeders
- With a lophophore → horse shoe shaped feeding organ of ciliated tentacles around the mouth
- Have four clades (considered phyla)
- Bryozoa: ‘moss animals’
- Entoprocta/kamptozoa
- Phoronida
- Brachipoda: ‘lamp shells’
Trochozoa
- Typically develop through a planktonic trochophore
larva
- Include mollusca, annelida and nemertea
-
Form of trochozoa often found in aquatic animals.

The benefits of buying summaries with Stuvia:

Guaranteed quality through customer reviews

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

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

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 elishakaur. Stuvia facilitates payment to the seller.

Will I be stuck with a subscription?

No, you only buy these notes for $6.95. You're not tied to anything after your purchase.

Can Stuvia be trusted?

4.6 stars on Google & Trustpilot (+1000 reviews)

68175 documents were sold in the last 30 days

Founded in 2010, the go-to place to buy study notes for 15 years now

Start selling
$6.95
  • (0)
Add to cart
Added