Animals Flashcards
animals
heterotrophic, eukaryotes, tissues from embryonic layers (muscle and nerve - think and move on our own)
reproduction
most sexually, diploid stage dominates
- zygote
- eight-cell stage
- blastula (hollow ball of cells)
- gastrulation (ball indents)
- gastrula
Gastrula and gastrulation
last stage of embryo before differentiation
- blastopore/protostome (indentation)
- archenteron (digestive tract)
- 3 germ layers: ectoderm, mesoderm, endoderm
cleavage
series of mitotic divisions without cell growth between the divisions, begins immediately after fertilization
larval stage
not yet adult, sexually immature, have to go through metamorphosis, different food sources and habitats
metamorphosis
developmental transformation from juvenile to adult (tadpole to frog- no legs or lungs and live in water), (caterpillar to butterfly- eats leaves then nectar)
ediacaran biota
550 million years ago, animals were extinct
cambrian explosion
535-525 million years ago, many phyla represented, flood
sponges
precursor to animals, collar cell- cilia and flagellum push water out of sponge and get food
animals can be characterized by
body plans
symmetry
mirror image on both sides of animal
radial symmetry
no matter where you cut it, it will always be cut in half (starfish)
bilateral symmetry
only one way to divide an animal into two halves
dorsal
back or upper surface
ventral
lower or front surface
anterior
towards the front (head)
posterior
towards the back end
cephalization
forming of head with concentration of sensory organs