Animal Diversity and Development Flashcards
What did animals evolve from?
A single celled protist
What is the closest living relative to Animals?
Choanoflagellates through morphological and molecular evidence
They showed colonial behavior which led to multicellular common ancestry
What are animals?
multicellular, heterotrophic eukaryotes with tissues developing from embryonic layers
What is the nutritional mode of the animal kingdom?
Chemoheterotrophs that ingest food
cannot construct their own organic molecules like plants can
do not feed by absorption of material
ingest food then use enzymes to digest it within their bodies
What type of genes to animals have, exclusively?
HOX genes which regulate development
Describe the development of animals.
Most animals reproduce sexually with the diploid stage
sperm and egg fuse to make a zygote
the zygote undergoes cleavage (rapid cell divisions)
Leads to formation of hollow balls, Blastula with a fluid center called the blastocoel
tissue formation though gastrulate
What is gastrulation?
cells migrate and fold into the blastocoel, forming the ectoderm, endoderm, and mesoderm
What is a blastopore?
where the digestive space, called the archenteron opens to outside
What are the four body plan characteristics?
symmetry
tissue layer
body cavity
embryonic development
What are the references for bilateral symmetry?
Dorsal: Top
Ventral: Bottom
Posterior: Back
Anterior: Front
What are the three true layers
Ectoderm: forms the outer layers, like skin and neurons
Endoderm: forms archenteron and digestive tissues
Mesoderm: forms muscles and skeleton
What is a diploblast?
animals with two tissue layers, the ectoderm and endoderm
What is a triploblast?
animals with all three layers
What is the body cavity used for?
allows for growth
cushion for internal organs
pressure-resistance in organism lacking rigid skeleton structures
What is the main difference between protostomes and deuterostomes?
Protostomes: cleavage is spiral and determinate
Deuterostomes: cleavage is radial and indeterminate
How is the coelom formation from Mesoderm different?
Protostomes: solid mass of mesoderm splits inside to make body cavity
Deuterostomes: layers of mesoderm pinch together
How does the blastopore differ?
Protostomes: mouth forms first
Deuterostomes: anus forms first
What happened during the Cambrian Period?
the Cambrian explosion brought a wave of animal diversification during the Paleozoic Era
Appearance of arthropods, chordates, and echinoderms with characteristics like mineralized shells, toothpick spikes, and grasping limbs
What happened during the Mesozoic Era?
coral reefs emerged
dinosaurs were dominant
first non-arthropod wings evolved
mammals first appeared
What was the KT Event?
Extinction Event that marks the Cretaceous-Tertiary Boundary
Describe the Cenozoic Era.
Begins with extinctions of terrestrial and marine animals
diversification of mammal orders and insects
