Week 1 Flashcards
Where did animal life begin?
Water
How long ago did the first animals arise
about 570 million years ago
Many animal phyla originated during the ____ explosion
cambrian
The beginning of animal life originated from a single ____
protist
what are the nine major phyla we are studying (invertebrates)
Chordates, Echinoderms, Arthropods, Roundworms, Annelids, Mollusks, Flatworms, Cnidarians and Sponges :-)
What makes the split between sponges and the other clade>
Sponges have no true tissues
where is the second branching point between true tissues in the taxonomic tree
radial symmetry versus bilateral symmetry
radial symmetry has ___ germ layers whereas bilateral symmetry has ___ germ layers
two, three
Which phyla has radial symmetry?
Cnidarians
Three germ layers contains the _____, _____ and the _____
endoderm, ectoderm and the mesoderm
In all phyla except for sponges, the embryonic ball of cells called a _____ folds in on itself, forming a _____
blastula, gastrula
what distinguishes the third branching point in the phylogenetic tree
embryonic development
If the first indention of the gastrula develops into the mouth, the organism is a _______
protostome
If the first indention of the gastrula develops into the anus, the organism is a _______
deuterostome
What is a difference between Ecdysozoans and Lophotrochozoans?
Ecdysozoans shed their exoskeleton, Lophotrochozoans have a feeding structure called a lopophore
T or F: A bilaterally symmetrical animal can have a coelom, pseudocoelom or no coelom
T
what is a pseudocoelom
a ““false” coelom
what is a coelom
empty space or cavity that is covered by organs, helps us able to flex and bend