Chapter 2 Flashcards
one of the several animal phyla, most complex animals but not most numerous, some features shared with other related phyla (bilateral symmetry, coelum, deuterostomes)
phylum chordata
fluid filled cavity in body
coelom (those that have these called coelomates)
usually shows spiral cleavage, coelom formation by splitting of the mesoderm, and derivation of the mouth from the blastopore
protostome
exhibit radial cleavage, coelom formation by outpocketing of the gut, and derivation of the anus from or in the vicinity of the blastopore
deuterostome
dividing cells of the embryo are offset from each other
spiral cleavage
dividing cells of the embryo are aligned
radial cleavage
opening into the gastrulation which is when one wall of the embryo begins to indent and grow inward
blastopore
central nervous system is hollow tube, neurocoele
dorsal tubular nerve cord
fluid filled cavity inside
neurocoel
flexible rod running along the length of the body, ventral to nerve cord
notochord
part of the digestive tract located immediately posterior to the mouth, series of openings
pharynx
acts as a sieve, capturing food particles, plus increasing surface area for oxygen absorption from water
pharyngeal slits
where pharyngeal slits are located
atrium
where atrium is able to secrete that which came from pharyngeal slits
atriopore
this was able to line the pharynx helping to snatch food particles from suspended organic material
mucus
this produces the water current in the pharynx and gathers the food-laden mucus to pass into the esophagus
ciliated cells
tail extends beyond position of anus, important in swimming
post-anal tail
myomeres are arranged sequentially along the body and tail as part of the outer body wall
segmentation
blocks of muscle
myomeres
chordates appeared during this period, difficult to figure out with few fossils, need to study protochordates to understand phylogeny
cambrian period
sea urchin, star fish, have larvae similarity (also molecular studies) with hemichordates, also deuterostomes
phylum echinodermata
acorn worms, have larvae similarity (also molecular studies) with echinodermata, have 1/2 chordate characteristics
phylum hemichordata
includes cephalochordata, urochordata
phylum chordata
amphioxus
subphylum cephalochordata
sea squirt
subphylum urochordata
fish, amphibians, reptiles, mammals, birds
subpylum vertebrata
animals that show some features of the most important chordates: vertebrates. these are all marine animals that feed by filtering sea water, phylum hemichordata, subphylum cephalochordata, subphylum urochordata
protochordates
hemichordata pass through a small planktonic stage called this
tornaria larva
lacks notochord or post-anal tail
poorly differentiated nervous system
have pharynx with slits
larval stage very similar to echinoderms
include proboscis, collar, and trunk
some ingest sediment
some filter feed
some vessels pulsate to move blood through dorsal and ventral vessels
acorn worm
wiggles and inflates to move into burrow, ciliated cells on surface move food towards mouth, also contains excretory organs and a heart
proboscis
the region of hemichordate contains the mouth
collar
this part of hemichordate contains pharynx (with slits), and gonads
trunk
this is the last steps in acorn worms after water has passed through the pharynx, then the slits, then through one of the branchial pouches then through this
branchial pores
inspired by the characteristic flexible outer body cover
tunicates (tunic)
complex pharyngel slits, the stigmata, sieve the passing water before it flows from the branchial basket into this place
atrium
slits in the pharynx walls proliferate and each subdivides repeatedly, producing smaller openings called this
stigmata
mucus producing, mid-ventral groove
endostyle
often send nerves to the rest of the body, brain, collections of neurons close to the sensory vesicle
cerebral ganglion
located next to the rudimentary pharynx contains navigational equipment thought to be involved in orientating the larva during its planktonic existence
sensory vesicle
capillaries end blindly, blood flow is reversible, blood not contained with vessels lined with epithelium, there are gaps where the blood can move into pockets of connective tissue or hemocoels
open vascular system
all vessels completely lined with epithelial cells or endothelium, myoepithelium lines the heart, this helps contract so the blood flows easier
closed vascular system
all chordate features present in adult
small, but very complex and efficient pharynx
complex mouth
intestines more complex with liver like hepatic cecum
closed vascular system
muscular beastie
more derived closed vascular system but no heart
powerful swimmer but prefers to sit in burrows and filter feed unless disturbed
amphioxus
located in the pharynx, help divide the branchial bars and filter water through to catch food
primary and secondary bars
encloses the anterior entrance to the pharynx and supports an assortment of food-processing equipment
oral hood
prevents entrance of large particles project from the free edge of the oral hood, like a sieve
buccal cirri
banks of ciliated cells that propel food into pharynx
wheel organ
part of amphioxus that secretes mucus
hatchek’s pit
provides a narrow opening to the pharynx
velum and attached tentacles
fibrous connecting tissue support the pharyngeal bars internally
supportive rods
dorsal channel in the pharynx
epibranchial groove
oxygenated blood leaves from this place in amphioxus to travel to the rest of the body
dorsal aorta
blood enters bars from this place in amphioxus
ventral aorta (endostylar artery)
this gave the first hint of fish fins and tetrapod limbs in amphioxus
fins and metapleural folds
return blood from the body, joining in pairs at the end
cardinal veins
meets with cardinal veins
hepatic veins
meets cardinal and hepatic veins and leads tot he endostylar artery
sinus venosus
