Week 9 Chordata Flashcards
Clades within Clade Chordata
Clade Chordata
- Clade Tunicata
- Clade Cephalochordata
- Clade Vertebrata
- Clade Gnathostomata
- Clade Agnatha
- Clade Cephalaspidomorphi
Clades within Clade Gnathostomata
- Chondrichthyes
- Actinopterygii
- Amphibia
- Reptilia
- Aves
- Mammalia
Clade Actinopterygii
- Freshwater and Marine
- Same general characteristics as last week
- (Ossified) bony endoskeleton
- Ectothermic
- External fertilization
- 2 chambered heart
What makes clade actinopterygii successful?
- Gills
- Gill Operculum - Movable flap covering each gill that can pump water over gills; do not need to be constantly swimming
- Swim bladder - allows bony fish to achieve neutral buoyancy and provides additional gas exchange
- Paired fins with bony rays - Increased support and stiffness that assist in maneuvering
Evolutionary history of bony fish
- Appear slightly earlier than cartilaginous sharks (evolved in freshwater)
- Ancestors had rudimentary lungs (class sarcoperygii)
- Class actinopterygii: underwent major adaptive radiation
- Common ancestor of amphibians and all other tetrapods was a group of lungfishes
Fins
-Supported by parallel bony rays (^ support and stiffness)
-are able to folded against body
(^ maneuverability)
KNOW: pectoral, pelvic, anal, dorsal, caudal
What is the purpose of the lateral line system
-To detect vibrations, pressure changes, and current directions
What is the advantage of a swim bladder?
It allows for a homocercal tail (symmetrical on top and bottom) which creates balanced muscular contractions and faster swimming.
What are the defining characteristics of clade amphibia?
- Represents the transition between aquatic and terrestrial habitats
- Aquatic larvae (w/ external gills) and tetrapod adults
- ectothermic
- MUST live in moist conditions
- 3 chambered heart which partially separates low O2 and high 02 blood
- external fertilization
What are amphibians adaptations for terrestial life?
- Lungs (they also respire via thin skin)
- 4 limbs allow for greater structural support against gravity
- Ectothermic - regulate body T via behavioral mechanisms (winter hibernation -> use fat bodies)
How do species within clade amphibia respire?
Frogs: Gills, then lungs
Salamanders: Gills, then lungs (though some retain gills)
Axolotls: metamorphosis under certain conditions
-Skin MUST remain moist to prevent dehydration and facilitate gas exchange.
What is unique to amphibian respiration compared to humans?
they use positive pressure ventilation (push vs. pull). They gulp air into their lungs.
Amphibian Circulation
- 3 chambered heart (2 atria, 1 ventricle)
- Double circuit system (separate pulmonary and systemic circuits)
- Partially separates oxygenated and deoxygenated blood
