Lab 2 - Phyla Porifera and Cnidaria

embryology

unique pattern of early development

sessile

non-moving

filter feeders

intracellular digestion

sponges

motile as embryos

no muscles, nervous system

morula

solid ball of cells

blastula

hollow ball of cells, single layer of cells

blastopore

opening

gastrula

multiple cell layers that differentiate into germ layers (ectoderm, endoderm) which becomes tissues and organs

archenteron

tube

develops from blastopore

becomes digestive system

excretory system

nitrogenous excretes

choanoflagellates

protists

most closely related to animals

diploblastic

2 germ layers

triploblastic

3 germ layers

spicule

skeletal elements

mesohyl

gel layer in porifera

epithelium

outer cell layer

choanocytes

collar cells

amoebocyte

move around to distribute food particles throughout sponge

functions:

• distribute nutrients

• produce gametes

• produce spicules

overall flow of water

incurrent canal → pores → excurrent (radial) canal → spongocoel → osculum

phyla cnidaria

radial symmetry

diploblastic

have true tissues

• muscles & nervous tissues

gastrovascular cavity (digestion)

stinging cells for prey capture

nerve net

a network of nerves coordinates sensory and motor functions (no central nervous system)

cnidocytes

stinging cells

nematocytes

capsules within cnidocytes

house a thread to capture prey

trigger

responds to touch or chemicals, causes thread to discharge

mesoglea

gel layer in between cell layers in cnidaria

obelia sexual reproduction

feeding polyp

female medusa

male medusa

obelia asexual reproduction

reproductive polyp

medusa bud

coenosarc

helps connect the entire colony

scyphozoans

true jellies