• multicellular, hertrotrophic eukaryotes.
• get preformed organic molecules through ingestion (eating other organisms or organic material that is decomposing)

• lack cell walls
• held together by structural proteins (ex. collagen(
• intercellular junctions: tight junctions, desmosomes, and gap junctions

• respons for impulce conduction and mvmt= nervous tissue and muscle tissue

• cleavage leads to this
• form of a hollow ball

• after blastula stage
• layers of embyonic tissues that will develop into adult body parts are produced

• results from grastulation

• sexually immature form
• eats diff food than adult
• sometimes diff habitat than adult

•  a resurgence of devolpment that transforms animal into an adult

• Hox genes
• modules of DNA sequences=homeoboxes (only in ansimals)
• # of Hox genes correlated w/ complexity of animal

parazoans

• lack true tissues
• sponges

• tissues are a basic feature of nearly all other animal phyla

• pylum Ctenophora (comb jellies) and phylum Cnidaria (jellies)
• radiata
• has a top and bottom, an oral and an aboral side but no head end and rear end and o left and right

• dorsal (top)
• ventral (bottom)
• anterior (head)
• and posterior (tail)
• two sided
• leaft and right side
• bilateria

• evo trend toward the concentration of sensory equip on the anterior end, the end of atraveling animal that is usually first to encounter food, danger and other stimuli

• embryo becomes layered through grastrulation
• these concentric layers form various tiss and organs

• covering the surface of the embryo
• gives rise to the outer covering of the animal
• and for some, the central nervous system

• innermost germ layer
• lines the developing digestive tube/archenteron
• gives rise to lining of the digestive tract and organs derived from it (liver and lungs(

• all eumetazoans except the radiat have this
• froms muscles and most other organs btwn the digestive tube and the outer covering of the animal

• ='s the cnidarians and ctenophores (radiata) b/c only have endoderm and ectoderm
• all other eumetazoans = triploblastic

acoelomates

• triploblastic animals w/ solid bodies
• no cavity btwn digestive trace and outer body
• phylum Platyhelminthes (flatworms)

• most phyla of bilateral triploblastic animals have tube within a tube body plans
• fluid spaced sep digest tract from outer body wall
• prevents injury
• in soft bod coelomates: functions as hydrostatic skel

• if cavity is not completely lined by tiss derived from mesoderm
• rotifers and roundworms= pseudocoelomates

• animal with true coelom
• fluid filled body cavity completely lined by tissue derived from mesoderm

• mollusks, annelids, arthropods
• cleavage='s spiral and determinate
• coelom formation: Schizocoelous: solid masses of mesoderm split to form coelom
• Fate of blastopore: mouth develops from blastopore

• echinoderms, chordates
• Cleavage: radial and indeterminate
• Coelom formation: Enterocoelous: folds of archenteron form coelom
• fate of blastopore: Anus develops from blastopore

protostomes

planes of cell division are diagonal to the vertical axis of the embyo

• protos
• rigidly casts the developmental fate of each embryonic cell very early

• deutero
• cleavage planes are parallel/perpendicular to the vertical axis of the egg

• deutero
• each cell prod by early cleavage divisions retains capacity to develop into a complete embyo

• protos
• as the archenteron forms in a protostome, initially solid masses of mesoderm split to form coelomic cavities

• deutero
• mesoderm buds from the wall of archenteron and hollows to become the coelomic cavities

blastopore

• annelids and mollusks
• go through trochophore larva

• arthropods

Platyhelminthes (flatworms)

• protostomes in which body plan became simplified by loss of the coelom later in evo

• secrete external skeletons (exoskel)
• armour of lobsters
• nematodes and arthropos
• as animal grows, it secretes new one=ecdysis