BIOL 111 Lecture Notes - Yolk Sac, Osmotic Concentration, Ovoviviparity

30 views3 pages
01/11/11
Chordates:
~ 53000 speices = very diverse
- Include the vertebrates
- Deuterostomes
- Coelomates
- Bilateral symmetry
3 unique characteristics:
1. Dorsal hollow nerve cord
2. Notochord: supportive rod internally (highly reduced in vertebrates,
replaced by spine)
3. Post-anal tail
Other characteristics:
1. Pharyngeal slits: found in chordates but not unique to them: seen first in
deuterostomes
2. Hollow dorsal nerve cord and segmentation is formed by neurulation
3. Central heart
4. Reduced segmentation
5. Segmented musculature
- myomeres
Deuterostomes include chordates
Pharyngeal slits:
- Pouches in human embryo
- Located on lateral surface of head
- In all vertebrates, ancestral trait in deuterostomes
- In vertebrates: are supported by arches: what become jaws and are
important for gas exchange
- For Filter feeding
- For respiration in vertebrates: water coming in mouth passes through slits
- O2 and CO2 can be exchanged across a respiratory surface = gills
- Supported by gill arches
Gills: bars in between the slits = gill arches
- made of bone or cartilage
- gill filaments on gill arches: respiratory exchange takes place
- In boney fishes: 4 pairs of gill arches
- Pairs of filaments down the filaments
- Gill raker: strained food, prevents food from exiting mouth through
gills
- Covered by operculum, protects gills
- Gills full of vascular tissue
- Filament structure:
= thin, vascularized, high surface area, moist, maintain partial pressure
Unlock document

This preview shows page 1 of the document.
Unlock all 3 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
Monthly
$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.