28 Flashcards
Hemichordata placement
sister to Echinodermata
Hemichordata
acorn worms, pterobranchs
Hemichordata spp
140
Hemichordata habitat
entirely marine
Hemichordata body
tripartite body with eucoeloms
whats used for feeding Hemichordata
pharyngeal slits
nervous system Hemichordata
dorsal and ventral nerve
cords
circ system hemichordata
heart and dorsal and ventral vessels, but the system is not completely closed
sexes Hemichordata
seperate sexes
what kind of reproduction Hemichordata
both sexual and asexual
within Hemichordata
Enteropneusta
Pterobranchia
Enteropneusta
solitary
tripartite body plan
tripartite body plan of Enteropneusta
proboscis
collar
trunk- has gill’ slits
what connects coelom to the water outside Enteropneusta
coelomopore
what does each body region have Enteropneusta
own eucoelomic cavity or pair of cavities
similar to Cephalochordata Enteropneusta
pharyngeal slits that may be may be homologous with chordate branchial slits
what does cilia on pharyngeal slits do Enteropneusta
generate current that sucks water through mouth and expels it through holes in pharynx to outside
proboscis is covered with
what is it used for? Enteropneusta
cilia and mucus and is used for feeding
where are desirable particles added? Enteropneusta
iodine-
rich mucus cord
Enteropneusta feeding
nonselective deposit feeders that create large casts of
undigested sediment- ike eartyhworms
where do enteropneusts live
some in burrows
others live on the surface of sediments
reproduction enteropneusts
asexually by multiple transverse fissions
and sexually via broadcast
spawning
Pterobranchia habitat
tube-dwelling, colonial
Pterobranchia body
tripartite
tripartite body of Pterobranchia
-cephalic shield
-collar with 2-10 tentacle-bearing arms and pharyngeal slits
-short globular trunk and stalk
what does each part of body havePterobranchia
or one two eucoelomic cavities
Pterobranchia how does zooid move up and down in tube
creeping
movements of the cephalic shield
what do pterobranchs feed on
feed on suspended particles
gut pterobranchs
U-shaped
Pterobranchia reproduction
asexual via budding
ferilization in Pterobranchia
external fertilization and
brooding
what are some pterobranchs fossiles known as
graptolites
graptolites
-all extinct now
- were diverse
-had planktonic colonies
Phylum Chordata
Vertebrata Cephalochordata and Urochordata
Phylum Chordata body cavity
coelomic cavity not tripartite and is reduced
what do pharyngeal slits/clefts do in chordata
-suspension-feeding
devices in many invertebrate
chordates
-aquatic vertebrates are gill
slits
Phylum Chordata features
-notochord
-dorsal, hollow nerve cord
-muscular, post-anal tail
- pharyngeal slits/clefts
-segmentally arranged muscle blocks
nerve cords in other animals are
solid and are almost always ventral
what is present in all chordate embryos
notochord
what does plate of ectoderm dorsal to notochord do
plate rolls into tube and develops into brain
what does endostyle do
secretes mucus and traps particles
what is present in Cephalochordata and Urochordata
endostyle
Urochordata and Vertebrata
are sister taxa
Cephalochordata
lancelets
adult Cephalochordata has
all the chordate character states
cephalo = head in cephalochordata why?
notochord extends
anteriorly beyond the nerve cord
how do cephalochordata extract particles
mucous
covered U-shaped pharyngeal slits
circulatory system Cephalochordata
closed
how is filtered water sent out of the body Cephalochordata
through atriopore
Cephalochordata endostyle
iodine-rich mucus net
Cephalochordata nervous system
dorsal nerve cord, no brain,
eye Cephalochordata
single non-image-forming eyespot
cephalochordata fertalization
external fertilization
cephalochodata sexes
seperate
larva in cephalochordata
plankatrophic for months
Urochordata spp
3000
Urochordata body covered in
tunic made of a cellulose-like polysaccharide
urochordata feeding
And what do they use
suspension feeders with large branchial filtering baskets;
Urochordata solitary or colonial
both
Urochordata nervous system
no brain, dorsal nerve cord only in larvae and in adults of one class
Class Ascidiacea
part of urochordata
Class Ascidiacea nervous system
lack notochord & nerve cord as adults
-their larva have it(tadpole)
Ascidiacea larvae
tadpole’ larvae
pharynx of Urochordata
huge pharynx with
many ciliated slits
what does endostyle do uropchordata
endostyle
secretes an iodine-rich mucus net
where is water sent after filtering
water is sent to the atrial siphon
ascidians colonial or solitary
colonial share a single tunic, and are connected to each other by tissues
ascidians sexes
hermaphroditic
reproduction ascidians
asexually by budding
tadpole
tadpole larvae have brief free-swimming phase and then attach to substrate by head
Class Larvacea
part of urochordata
adults in larvacea
adults retain notochord and dorsal nerve cord and look rather like the tadpole larvae
Larvacea thought to have evolved via
paedogenesis
paedogenesis vs paedomorphosis
paedomorphosis: retention of juvenile characters in adults
paedogenesis:sexual maturation while still in a juvenile or larval form)
not much difference
what do larvaceans make to suspenstion feed
mucus houses
echinoderm larvae importance
food webs as prey and as
predators
predation by sea stars structures
intertidal zonation
starfish wasting syndrome
mfs gettin fucked
invasive species of tunicates
fouling man-made objects and smothering native shit which blocked photosynthesis
echinoderms important models for
-studies of deuterostome-
style development
-larval cloning
E & I echinoderms
humans eat echinoderms
-cephalochordates and urochordates
