Exam 1: Bilateral Symmetry

animals with Bilateral Symmetry can have a _____ nervous system

More advanced

- head, brain (cephalic ganglion)

Triploblastic

Grastula has 3 layers

- can have in/complete digestive tract

- can rely less on diffusion

Why can triploblastic organisms rely less on diffusion

They can have a circulatory system; respiratory system and/or excretory organs

Radial Cleavage

Among vertebrates; echinoderms, etc.

- cells divide at right angles

- cells equal in size an shape

- can have stem cells- cell fates depend on stage and location

- can get identical twins

- regulative development

Spiral Clevage

Most invertebrates

- divide at oblique angles

- cell fates fixed: no id, no twins , no stem cells

- ideal for genetic studies of mutations

macromeres

large cells with yolk

- at one end of the embryo Vegetal pole

micromeres

Small cells, no yolk

- at animal pole