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Vertebrates (Chordates (Four morphological features of chordates…
Vertebrates
Chordates
The phylum that vertebrates belong too (Cordata)
Four morphological features of chordates
Dorsal, hollow-nerve cord
Precursor to the central nervous system
Pharyngeal slits
Pouches along the sides of the pharynx
In animals without limbs, it develops into gills for gas exchange
Functions as suspension-feeding device in invertebrate chordates
In
tetrapods
(vertebrates with limbs) develops into ears, head, and neck
Notocord
A cartilaginous skeletal rod in the embryo
In humans, it develops into the intervertebral discs
Muscular, post-anal tail
Often reduced during embryonic development
Humans have tails during embryonic development
Early chordates included lancelets and tunicates
Lancelets do not have brains but have swollen tips at anterior of nerve cord, and possess genes for the development of a brain
Tunicates have genes present in vertebrates that are not present in non-chordate invertebrates
Chordates with a developed head are
craniates
Hagfish are
least derived
in this lineage
Least derived refers to a lineage that has changed little of the least over time
Vertebrates descended from this lineage
Lampreys are the oldest lineage of vertebrates
They do not have a jaw, so they must latch on as parasites
Gnathostomes
have jaws and an enlarged fore brain, mostly associated with smelling and vision
They can obviously bite
Most ancient lineages include
chondrichthyans
, ray-finned fish, and lobe-finned
Chonrichthyans
Means "cartilage fish"
Has a skeleton that is predominantly cartilage
Sharks and rays
Sharks
2 more items...
Rays are bottom-dwellers with powerful jaws to crush mollusks and crustaceans
Ray-finned fishes
Typical fish...
Fins specialized for maneuvering, defense, etc.
Good source of protein (don't tell Richard)
Lobe-finned fishes
Only a few surviving lineages
Supposedly gave rise to tetrapods
Tetrapods
3 more items...
Rod shaped bones surrounded by muscle in fins, thought to be used to 'walk' under water
One lineage is lungfish, which gulp air into lungs, and can survive drought by burrowing into mud
"The reason that lobe-finned fish aren't prevalent is that they once were, but climate change killed most of them"
Most fish have a
swim bladder
which controls their buoyancy; it is thought that lungs evolved into these