what is the closest relative to tetrapods?
sacropterygii
terrestrial habitats lead to
opportunities for adaptation and exploiting new niches
air environment (movement to land)
- density- 1000 times less
- oxygen content greater (20 times)
- does not provide buoyancy
- temp changes quickly
jawed fish nares characteristics
- paired nares
- inhalent/exhalant (anterior/posterior)
- connected to olfactory chamber
- olfactory nerve connects to olfactory
- lots of anatomical variability
- important role in feeding in many species
- communication, reproduction, migration, avoidance (alarm, cues)
choana
internal naris/nares
- passage between nasal cavity and throat
what is choana an important feature of?
tetrapod development
- draw air through the nose into the lungs
- developed before limbs originated
what do not have choanae?
ceolocanths
where is the migration from external nares to internal nares apparent?
in Kenichthys an extinct fish
amphibian characteristics (7)
- skeleton mainly calcified bone
- tetrapods (4 limbs)
- 2 loop circulatory system
- no scales (thin skin- moist, glandular)
- ectothermic
- eardrum & stapes
- paired internal nostrils open to nasal cavity
what is the stapes (columella) used for?
transmitting vibrations to inner ear
what are the internal nostrils lined with>
olfactory epithelium at anterior part of mouth cavity
why are amphibians tied to water?
- eggs deposited in water or must be kept moist
- larvae depend on gills for respiration
- thin skin loses water rapidly
what are amphibians respiratory mechanisms?
- skin
- gills
- lungs
- both gills and lungs
- or neither
- vascularized lining of mouth cavity
what are the 3 orders in the subclass lissamphibia?
- gymnophiona
- urodela
- anura
urodela (newts and salamanders) 7 characteristics
- primitive amphibians
- simple shape
- legs are weak and small
- body often partly drags along the ground
- good swimmers
- mostly occur in NA
- small although some reach 1M in length
