CVA Exam 1 (2022 Answered) Graded A+
5 chordate synapomorphies
1. pharyngeal wall with bilaterally symmetrical pharyngeal pouches and pharyngeal slits
2. Mid-dorsal hollow nerve cord (in humans:spinal cord)
3. a single, mid-dorsal supportive rod, the notochord (in humans:intervertebral discs)
4. a muscular postanal tail at some stage in life (in human: coccyx)
5. endostyle (precursor to thyroid) or thyroid gland
characters found in some inverts or absent in some chordates
1. segmented body (metamerism)
2. a coelom, or true body cavity
3. bilateral symmetry
4. sense organs and nervous system concentrated in the head (cephalization) or distinct
brain
______ is the anterior extension of the spinal cord
brain
endostyle
precursors to thyroid gland located at base of the pharynx that binds to iodine
automorphy
uniquely derived character not shared by others
phylogeny
lineage+genesis
the course of evolution, coined by Haeckel
dendogram
treelike diagram used to display phylogeny with branching patterns of evolutionary lines
ancestral character
Evolved in a common ancestor of both groups
doesn't show deviation between two clades
aka primitive or plesiomorphic
derived characters
characteristics that appear in recent parts of a lineage but not in its older members, a
defining character that separates 2 clades
aka apomorphic
cladistics
recognizes glades and construct cladograms that are based on apomorphies or
synapomorphies
clade
includes an ancestral species and all its descendants.
cladogram
specialized dendogram that show monophyletic lineages
apomorphy
unique derived character
synapomorphies
,shared derived characters
monophyletic
ALL descendants and its common ancestor
paraphyletic
Pertaining to a group of taxa that consists of a common ancestor and some, but not all,
of its descendants.
ie excluding birds from reptiles
Polyphletic
a group that doesn't share a common ancestor, based on nonhomologous characters
defining character of archosaurs (maybe earlier)
feathers
outgroup
most ancestral external group, ie crocs when looking at birds
eutherian
true placental mammal that gives birth to live young that have completed fetal
development
deuterostome
includes echonoderms, hemichordates
exhibits
-radial cleavage
-blastopore forms anus
-enterocoely by mesoderm pinching off from endoderm within archenteron
coelom
body cavity
protostome
includes inverts
exhibits:
-blastopore forms mouth
-spiral cleavage
-schizocoely by coelom forming by splitting of mesoderm in two layers
protochordates
share some or all chordate characteristics and were among earliest chordate-like
animals
paraphyletic group that includes hemichordata, urochordata and cephalochordata
hemichordata
-solitary or colonial marine mammals that share some chordate characters like
pharyngeal pores/slits but lack notochord and postanal tail
-most common are acorn worms, marine worms that live in marine sediment
-other group is pterobranchs that filter feed by waving its mucus-covered arms, they are
similar to early echino
-hemichordate larva very similar to echinoderm larva
defining characteristic of chordata
notochord, a supportive rod
many early chordata were also filterfeeders
, urochordata/tunicata
-most are sea squirts (tunicata) with outer tunic strux
-sea squirt "tadpole" larva have all 5 chordate characters (some have postanal tail),
have adhesive papillae, swim, and don't feed
-adult sea squirts are sessile marine animals that only maintain pharyngeal slits for
filterfeeding
-they filterfeed by using cilia to move water from the incurrent siphon out the excurrent
siphon out the side
Cephalochordata
-small fish-like marine animals that possess all chordate characters
-best known as amphioxus, it spends most of its time buried in mud
-these pre-vert suspension (filter) feeders use cilia on their wheel
organ to produce a current drawing food in the mouth and out the pharyngeal slits
-notochord goes into head, has segmented muscles like a fish, lacks a brain, has
photoreceptors that respond to light (not eyes) and a simple nervous system
pharyngeal slit first evolved for
filter feeding, not respiration
lophophore
a crown of ciliated tentacles that function in feeding
progenesis
accelerated development of the reproductive organs relative to the rest of the body that
results in reproductive maturity of larval stage
-also known as peramorphosis and occurs in many amphibians allowing larva to
reproduce
paedmorphosis
the retention of body structures (ie tail and notochord) that were juvenile features in
ancestral species
T/F all echinoderms are marine
true, and many inverts
closest living relative of vertebrates
tunicates (urochordata)
craniata
have a braincase, evolutionarily started as cartilage now bone
agnathans
jawless fish that also lack cartilage and bone
-used a muscular pump to produce a food-bearing water current
haikouella
primitive fossil fish-like chordate that has eyes, gills and a brain; lacks cranium but is
cephalized
oldest ancestor of craniata, that had a massive die-off in China
Myxiniformes
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