Shape of form

How parts are arranged in relation to planes of axis

No Shape

Amoeba

Arranged around a central point and can be divided along planes.

Example starfish

cut down the middle right and left sides are mirror images of each other.

Example: Butterfly

Superficial

(can either be internal or external)

External superficial: only on the outside.

Example: Starfish

Internal superficial: Only inside

Example: Human (diaphragm)

Superficial and Internal: internal and out

Segments are the same

Example: Earthworm

segments that are different

Example: Crayfish

Ectoderm: Outside, gives rise to skin and nervous system

Endoderm: inside, forms lining of the gut and digestive organs

Mesoderm: Middle, it becomes the musscles, skeleton, connective tissue and circulatory structures

2 germ layers

Ecto and endo derm

3 germ layers

Ecto, endo and mesoderm

Coelom

(body cavity in addtion to digestive cavity)

• Acoelomates: no body cavity
• Pseudocoelomates: false body cavity located between endo and mesoderm. they lack epithelial lining ( no peritoneum
• hemocoel filled with blood
•  Coelomates: true body cavity, located with in mesoderm
• lined with epithelial tissue (peritoneum)
• internal organs suspended by double layers of mesoderm known as mesentery, fluid filled

coelomates embryonic dev't

(Protostome)

• Protostome- first mouth, primitive
• Blastopore- openning in the gastrula stage of an embroyo
• mouth dev't near blastphore
• coelom forms by splitting the mesoderm
• spiral cleavage

coelomates embryonic dev't

(Deuterostome)

• Deuterostome- second mouth, advanced
• anus forms at or near blastopore
• mouth forms elswhere
• coelom formed by out pouching of the emryonic gut
• radial cleavage

Reproduction

Asexual

sexual can either be

(dioecious or monoecious)

• dioecious:- 2 separate sexes
• monoecious:- individual but has both male and female reproductive organ (hermaphroditeL

•  Primitive:- response to stimuli
•  Cephalization