Branchiostoma Flashcards
v shaped muscle fibres
Myomeres
divisions between myomeres
myosepta
reproductive organs, located posteroventrally
gonads
external portion of feeding apparatus
oral hood
slender tentacles that fringe opening of oral hood
oral cirri
chamber into which water and suspended food particles first enter the amphioxus feeding apparatus
buccal cavity
entrance into the buccal cavity, located anteroventrally
inhalant aperture
smaller opening within velum
mouth
demarcates oral cavity from pharynx
velum
extends along dorsal surface of body
dorsal fin
filled by a gel-like substance, supports dorsal fin
fin ray boxes
lies along, approximately, the posterior quarter of the ventral surface
ventral fin
extends anteriorly from the dorsal fin and wraps around the rostrum
rostral fin
expansion of dorsal and ventral fin extensions into the postanal tail
caudal fin
ventrolateral fins extending anteriorly from the ventral fin almost to the anterior end of the body
metapleural folds
the exit of the atrium, lies just in front of the ventral fin
atriopore
exit of the digestive tract, opens ventrally just posterior to the ventral fin
anus
midventral groove extending longitudinally along the floor of the pharynx
endostyle
middorsal groove, extends longitudinally dorsally along the pharynx
epibranchial groove
extends from the tip of the rostrum into the tip of the tail, it has a striated appearance and lies just dorsal to the pharynx anteriorly and the digestive tract
notochord
lies dorsal to the notochord and extends almost as far anteriorly and posteriorly, for most of its length it is about a third as thick as the notochord
dorsal hollow nerve cord
dark, at the anterior end of the nerve cord
frontal eye
photoreceptors that appear as dark granules along the ventral part of the nerve cord
Hesse ocelli
a series longitudinal finger-like bands that are united posteriorly to form an organ
wheel organ
fringe the margin of the mouth
velar tentacles
second chamber water enters, after passing through pharyngeal slits
atrium
initial part of the postpharyngeal gut
esophagus
expanded region directly following esophagus
midgut
evagination of the ventral floor of the midgut to form a diverticulum
hepatic cecum
posterior to the diverticulum the midgut narrows gradually into its posterior portion, an easily recognizable dark band
iliocolon
a fairly straight, narrow tube that leads to the anus
hindgut
