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
what is an incomplete digestive tract
the mouth both takes in food and ejects wastes
what is the term for repeated segments
metamerism
T or F: natural selection can act on segments separately in animals with segmented bodies
T, which leads to different species like crabs and lobsters
what are some advantages of segmented bodies
more flexible, have more potential for developing specialized body parts
What is the phylum Porifera
SPONGES!! :)
what are some characteristics of sponges
filter feeders: draw water through pores
collar cells with flagellum help sponges flow water inside
cephalization
asymmetrical
