[[Unit 1 Diversity of Living Things]]
Multicellular eukaryotes.
Cells lack cell walls.
Heterotrophs.
Mobile in at least one stage of life.
Sexual reproduction.
![[Pasted image 20261001105644.png]]

# Level of Organization 
Cells, tissue, organs, organ systems.
Sponges only have 2 layers of cells, no tissues.
"Hydra, jelly fish, corals, sea anemones: 2 layers of cells, but have tissues like
muscle and NS"

# Number of Body Layers: 
Do they have 3 layers (ectoderm, mesoderm, endoderm).
Ectoderm: Skin and ns, shell, scales, feathers.
Endoderm: Inner lining of gut, respitory system.
Mesoderm: Circulatory, reproductive, excretory, muscular.
"Sponges, corals, hydra, jelly fish do not have 3 body layers"
![[Pasted image 20261001110343.png|417]]

# Symmetry and Body Plans: 
Radial symmetry, bilateral symmetry, no symmetry.

# Body Cavity
Fluid filled body cavity called coelom.
![[Pasted image 20261001110522.png]]

# Segmentation
![[Pasted image 20261001110549.png]]

# Embryonic Openings
Protostomes: Opening develops into mouth.
Deuterostomes: Opening develops into the anus. 

# Movement
Sessile/stationary (attach to one place as an adult) vs ability to move.

# Reproduction
Mainly sexual, internal vs external fertilization.

# Presence of Backbone
Vertebrates vs invertebrates.