Week 9 Chordata

Question 1

Clades within Clade Chordata

Answer 1

Clade Chordata

• Clade Tunicata
• Clade Cephalochordata
• Clade Vertebrata
  - Clade Gnathostomata
  - Clade Agnatha
  - Clade Cephalaspidomorphi

Question 2

Clades within Clade Gnathostomata

Answer 2

• Chondrichthyes
• Actinopterygii
• Amphibia
• Reptilia
• Aves
• Mammalia

Question 3

Clade Actinopterygii

Answer 3

• Freshwater and Marine
• Same general characteristics as last week
• (Ossified) bony endoskeleton
• Ectothermic
• External fertilization
• 2 chambered heart

Question 4

What makes clade actinopterygii successful?

Answer 4

• 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

Question 5

Evolutionary history of bony fish

Answer 5

• 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

Question 6

Fins

Answer 6

-Supported by parallel bony rays (^ support and stiffness)
-are able to folded against body
(^ maneuverability)
KNOW: pectoral, pelvic, anal, dorsal, caudal

Question 7

What is the purpose of the lateral line system

Answer 7

-To detect vibrations, pressure changes, and current directions

Question 8

What is the advantage of a swim bladder?

Answer 8

It allows for a homocercal tail (symmetrical on top and bottom) which creates balanced muscular contractions and faster swimming.

Question 9

What are the defining characteristics of clade amphibia?

Answer 9

• 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

Question 10

What are amphibians adaptations for terrestial life?

Answer 10

• 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)

Question 11

How do species within clade amphibia respire?

Answer 11

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.

Question 12

What is unique to amphibian respiration compared to humans?

Answer 12

they use positive pressure ventilation (push vs. pull). They gulp air into their lungs.

Question 13

Amphibian Circulation

Answer 13

• 3 chambered heart (2 atria, 1 ventricle)
• Double circuit system (separate pulmonary and systemic circuits)
• Partially separates oxygenated and deoxygenated blood