Chapter 27 Flashcards
symmetry around a central axis
cnidarians and ctenophoras have this symmetry
radial symmetry
is able to divide into two equal parts
platyhelminthes
bilateral symmetry
embryo development
fertilization –> blastula –> gastrula
an animal embryo at the early stage of development when it is a hollow ball of cells
blastula
an embryo at the stage following the blastula, when it is a hollow cup-shaped structure having three layers of cells
gastrula
a layer of tissue on the outside of a mammalian blastula, supplying the embryo with nourishment and later forming the major part of the placenta
trophoblasts
fluid-filled cavity within the blastophore
blastocoel cavity
a pit in the side of the embryo, through which cells fated to be endodermal flow so that they leave the outer surface of the embryo and can create a new inner surface
blastopore
having a body derived from only two embryonic cell layers (ectoderm and endoderm, but no mesoderm)
diploblastic
having a body derived from three embryonic cell layers (ectoderm, mesoderm, and endoderm)
triploblast
is an invertebrate that does not have a coelom or body cavity, only cavity is the digestive cavity and it only has tissue, and ectoderm and an endoderm
ex: platyhelminthes (tapeworm, planarians, trematodes or flukes)
acoelomates
an organism with a “fake” body cavity, has an ectoderm, endoderm and mesoderm
ex: nematodes
pseudocoelumates
animals that have internal body cavities, or coeloms; ectoderm, endoderm and coelum
Ex: humans
true coelom or coelomates
function of coelom
space and protection
the ectoderm is…
skin and nervous system
the endoderm is…
lining of the digestive tract, some organs
the mesoderm is…
muscles, connective tissue
a multicellular organism whose mouth develops from a primary embryonic opening
cells are determined
protostome
these phyla are protostomes
annelids, molluscs, arthropod
type of animals whose anus develops first in embryonic development
their cell fate is not determined
deuterostomes
examples of deuterostomes
echinodermata, chordate
two types of cnidarians
jellyfish
sea anemone
one type of ctenophora
comb jellies
types of lophotrochozoa
platyhelminthes rotifers ectoprocta brachiopoda mollusca annelids
types of ecdysozoa
nematodes
arthropods
tardigrada
