7 Phyla of Animals: Bilateria

Major features of bilateria

tripolasitc, bilateral symmetry, anterior/posterior axis, cephalization

cleavage

in the early stages of cell division after zygote formation, resulting in multiple cells (blastomeres), and an establishment of a longitudinal axis (animal-vegetal axis)

radial cleavage

right angles, symmetrical pattern

spiral cleavage

oblique angle, derived condition that characterizes the clade lophotrochozoa (mollusks and annelids)

if the mesoderm itself creates the cavity inside itself, this is what the cavity is called

coelem

Two major groups of bilateria are differentiated by

blastopore fate.

protostomes—blastopore becomes mouth.

deuterostomes—-blastopore becomes anus first.

proteosome or deuterostome

proteosome because the mesoderm cells form near the lips of the blastopore—if a coelom is present, its from the splitting of the mesoderm.

proteosome or deuterostome

deuterostome because the mesoderm cells and coelom form from outpocketing of cell wall

acoelomate plan

lack a true body cavity (coelum)

flatworms and roundworms are examples of __________. Earth worms are________.

acoelomates; true coelomates

traits associated with bilateral symmetry

segmentation, increased sensory and locomotor ability,