Ch. 27 - Animals Flashcards
When did animals originate?
700 mill years ago
edicaran biota
an early group of soft-bodied multicellular eukaryotes that make up the earliest fossils
sponges are what phylum?
porifera
filter feeders
they filter out food particles suspended in the water as they draw it through their body
basal animals
lie near the root of the phylogenetic tree
tissues
groups of similar cells that act as a functional unit
choanocytes
collar cells, flagellated feeding cells found in sponges
amoebocytes
named for the use of pseudopodia, cells that move around the sponge body and transfer food and carry the nutrients to cells
cnidarians
jellies, etc
eumetazoans
true animals, members of a clade of animals that have tissues
gastrovascular cavity
a cavity with a single opening in the body of certain animals that functions in both the digestion and distribution of nutrients, both a mouth and anus
bilaterians
an enormous clade whose members have a complete digestive tract and a two-sided bilaterally symmetric form
body plan
a particular set of morphological and developmental traits
radial symmetry
symmetry in which the body is shaped like a pie or barrel, lacking a left and right side
bilateral symmetry
animal has two axes of orientation
dorsal
top
ventral
bottom
anterior
front