Chordata Flashcards
What is the notochord?
A strong but flexible rod, like a spine
What are the synapamorphies of the chordates?
A notochord Dorsal hollow nerve tube parallel to the notochord Gill slits on wall of the pharynx Tail that extends past the anus Segments
What are pharyngeal slits?
Pairs of opening through the pharynx
What do invertebrate chordates use pharyngeal slits for?
They use them to filter food
What do juvenile fishes use pharyngeal slits for?
Breathing
In reptiles, birds and mammals what are the pharyngeal slits?
Vestiges only present in the embryo
What are the 3 subphyla of the chordates?
Cephalochordata
Vertebrates
Urochordata
What are cephalochordates?
Lancelets
What are the 3 key traits of the cephalochordates?
Filter feeders
Cirri strain large food particles
Marine animals
What are tunicates?
Urochordata
What are the 7 characteristics of the urochordata?
Marine animals Solitary/Colonial Sessile as adults Motile as larvae Filter feeders Adult body covered by a tunic Adults only exhibit pharyngeal pouches
What are the characteristics of the Vertebrata?
Vertebral column or spine Cranium that protects the brain Endoskeleton composed of bone or cartilage Well cephalised Muscles are attached to the skeleton Muscular perforated pharynx Closed circulatory system Muscular heart Blood is oxygenated as it flows through gills/lungs
What is Garstang’s hypothesis?
That the larvae failed to metamorphose p, and became sexually reproductive creating a new breed of chordates. This is known as pedomorphosis.
What animal are the vertebrates believed to have evolved from?
Pikaia
What are the amniotes?
The first vertebrate to adapt to dry land.
