BIOL 111 Lecture Notes - Oligochaeta, Hirudin, Nephridium

14 views4 pages
Development of digestive tract enables:
1. specialization of gut regions
2. sequential food processing
3. continuous operation (multiple tasks at once)
Gastrulation occurs = development of gut cavity
Blastopore forms then second opening forms
1. Protostomes (1st is mouth)
a. blastore mouth
b. new opening anus
2. Deuterostomes (2nd is mouth)
a. Blastopore anus
b. New opening mouth
1. Lophotrocozoans: have one of the characteristics:
- lophophore: ciliated feeding/gas exhange structure
- trocophore: ciliated free living larval form
- unsure about rise of these two forms, perhaps common ancestor had both
and some lost one
2. Exdysozoans:
- have external covering secreted by epidermis that must be shed in order for
animal to grow
Presence /type of body cavities (coelom) differentiate protostomes:
1. Pcoelomate: no coelom, solid digestive space (ex. Flat worms)
a. mesenchyme: unspecialized cells derived from mesoderm
2. Pseudoceloemate: false coelom (ex nematodes)
a. mesoderm lines the outside of coelom
3. Coelomate
a. Mesoderm lines entire cavity (peritoneum)
i. Lining derived from mesoderm
2 ways to make a coelom:
1. Schizocoely:
a. Splitting within the mesoderm form ceolom
b. In protostomes
2. Enterocoely:
a. Mesoderm forms pochets from guy
b. In deuterostomes
Phylum nematoda: Roundworms
- Blunt anterior end/tapered posterior end
- Ecdysozoans diffusion of gas across thin flexible cuticle
o Live in moist habitats to help with diffusion of gases across
Unlock document

This preview shows page 1 of the document.
Unlock all 4 pages and 3 million more documents.

Already have an account? Log in

Get OneClass Notes+

Unlimited access to class notes and textbook notes.

YearlyBest Value
75% OFF
$8 USD/m
$30 USD/m
You will be charged $96 USD upfront and auto renewed at the end of each cycle. You may cancel anytime under Payment Settings. For more information, see our Terms and Privacy.
Payments are encrypted using 256-bit SSL. Powered by Stripe.