Protochordates

Question 1

features of cephalochordates?

Answer 1

filter feeding, marine, motile w/ strong swimming
29 species
sexual reproduction - two sexes - seasonal broadcast spawners
show regulative development
possible post anal tail, gill slits

Question 2

features of urochordates?

Answer 2

tunicates
marine, filter feeders, sessile and motile 
notochord in tail 
fast evolving 
asexual and sexual 
important in biofouling

Question 3

what is the tunic?

Answer 3

hard covering containing tunicin

important microbiotal environment

Question 4

features of ascidiacia?

Answer 4

colonial forms with biphasic sexual and asexual life cycles
free swimming larva, sessile adults
settle on substrate and undergo dramatic metamorphosis
solitary and colonial forms

Question 5

features of thaliacea?

Answer 5

pelagic and free-floating
gelatinous and transparent
some emit light
solitary and aggregate/long chain colonial forms
alteration of sexual and asexual generations
tadpole stage lost

Question 6

features of larvacea?

Answer 6

pelagic, rapid gen time, second most abundant component of phtyoplankton
secrete a mucous house which is used to filter feed, discarded and remade 2-40x a day

Question 7

what is the notochord?

Answer 7

cartilegous skeletal rod of mesodermal origin
structural role - support swim
produces signals to help pattern nerve cord
lineage determined but origin unknow
elongates via intercalatation of cells

Question 8

what are vertebrate evolution trends?

Answer 8

elaboration of CNS/brain
circulatory system with pumping heart
evolution of head/adaptive immune system
increased complexity of genome

Question 9

how have head and circulatory systems evolved in protochordates?

Answer 9

head - changes in CNS, evolution of neural crest, feeding apparatus modified
circulatory - open/closed, no heart but contractile vessels which lack endothelium, blood has no pigment