1. Cell #, Emryology, and symmetry
2. Developmental Pattern 
3. Habitat 
4. Form 
5. Function 
6. Evolutionary Relationship

Bilateria - only one plane of symmetry 

•      Cephalization 

Radiata - Infinate number of planes that pass through its center 

No layers 

Diploblastic 

Triploblastic 

• Acoelomates 
• Pseudocoelomates 
• Coelomates 
• Protostome 
• Deuterostome

Majority of invertebrates 

Triploblastic animals with an internal, fluid-filled body cavity lying between the gut and outer body wall that comes from mesoderm. 

1. Cell Cleavage - Spiral Clevage 
2. Early Cell Fate - Determinate 
3. Origin of Mouth - Blastopore=mouth => mouth first
4. Mesoderm origin - Single cell located at the edge of blastopore. 
5. Formation of Coelom - schizocoely - gradual enlargement of a split in the mesoderm 
6. Cilia per cell - multiciliate 

1. Cell cleavage - Radial 
2. Early Cell Fate - indeterminate 
3. Origin of Mouth - Secondarily, not from blastopore 
4. Origin of mesoderm - From archenteron (cavity which becomes gut). 
5. Coelom formation - entercoely - envagination of the archenteron into the blastocoel. 
6. Cilia - monociliate 

1. Pelagic - water column 
2. Benthic - surfaces
• Epifauna - On surfaces 
• Infauna - within surfaces 
• Meiofauna - Moving between sediments 

1. Growth 
• Unitary - increased size of whole 
• Modular - addition of parts 
2. Skeletal support 
• Endoskeletal 
• Exoskeletal 
• Hydrostatic 

1. Feeding 
• Deposit feeding 
• Suspension feeding 
2. Reproduction 

• Broadcast spawning
• Internal fertilization
• Copulation (Barnacle has largest penis)
• Can be sessile or mobile

3. Spermcast spawning ( suspension feeders)

Etc (locomotion, defense/protection, gas exchange, circulation, excretion, nervous control and sensory systems)

Should reflect degree of relatedness (phylogeny) 

Kingdom 

Phylum 

Class

Order

Family 

Genus

species 

1. Polyphyly - Name a group because they appear similar but infact they are on different parts of family tree 
2. Paraphyly: Because of this, members are closely related but some are left out. 

Vs. Mophyly: A Clade  

1. Naming them for something they do not have. 
2. 1,200,000 (96%) "invertebrate" species vs 45,000 (3%) Vertebrate species
3. Given the name invertebrates - they are paraphyletic group and therfore not a clade!

Forms a monophyletic group. A group that includes the most recent common ancestor of all its members and all descendants of that ancestor. 

An incorrect grouping containing species that descended from two or more different ancestors.

Do not share same immediate ancestor. 

May resemble each other due to homoplasy. 

Approximately 32 phyla. 

Arthropoda - ~77% of all animals 

~8% mollusca 

~6% nematoda 

Bilateria 

"Coelomates"

"Deuterostomes" and "Protostomes" (Proto splits into)

Lophotrochozoa and Ecdysozoa 

"first animals" or "animal like" protists 

Unicellular eukaryotes that blur the distiction between animals and plants 

35,000 Species 

All multicellular live must have evolved from protists 

All are nonphotosynthetic in the primitive condition 

1. Nutrition: heterotrophy: food vacuoles = Introcellular digestion. 
2. Volume regulation: contractile vacuoles
3. Movement: Undulipodiea = Cilia (conservative microtubles in 9+2 arrangement) and flagella 

Sponges - Cellular grade (no tissue) 

Mostly no symmetry = phenoplasticity 

Microfibrils on choanocyte collar 

Spongin Fibers: Polymerized collagen 

Cells around the outside of porifera used for protection. 

Cells used for majority or Porifera functions 

Movement, feeding, gametes, etc 

Contractile cells opening in Porifera.

Type of contractile cells found in sponges without porocytes. 

Cells of sponges that differentiate into all other cell types

Also forms "skeleton" to be called sclerocytes 

Made of inorganic CaCO3 or SiO2 surrounding the sclerocyte which is the organic protien core. 

Variety of shapes and sizes distinctive for taxa 

Makes up Spongin exoskeleton 

1. Asconoid: simplist (Possibly earliest grade) 
2. Syconoid: Choanocyte channels to increase surface area 
3. Leuconoid: Thick wall, Most complex, Most sponges, High internal Surface Area 

SA must supply volume 

For the same shape, SA/V is always l^-1 

Water enters trough Ostium and exists osculum 

Amebacytes catch inorganic particles and transport them 

water slows inside chambers allowing for more particle caprute. As the cross sectional area increases, the flow velocity decreases 

Shoots out water so quickly that it doesn't filter it again. 

The faster the flow the lower the pressure : velocity = 1/pressure 
Current at osculum is faster, therefore pressure is lower. At bottom however, flow velocity is slower and pressure is higher so the water moves naturally for high pressure to low pressure. 

Penotypic plasticity 

Grow taller in low flow areas to maximize pressure gradient. and vis versa 

Cells can move 1mm/min (compared to our .001mm/min)

Whole sponge can move up to 4mm/day 

Protection!! because they are sessile 

Some can grow on carapace of crab 

Some grow silica spicules 

Boring sponges use bioerosion to bore into CaCO2 substances. 

Symbiosis

Cyanobacterium bymbiont inside sponge tissue . Some have glass spicules to transport light to cyanobacterium. 

1. Cavity housing an incompressible fluid that transmits pressure changes in all directions uniformly 
2. Cavity must be surrounded by a flexible membrane. 
3. Fluid volume within cavity must remain constant 
4. The animal be capable of forming temporary attachments to the substrate, if progressive locomotion is to occur on or within a substrate. 
5. A deformable but elastic covering or the presence of at least two sets of muscles that can act against each other. 

1. Secretion of complex intracellular organelles called cnidae (nemaocysts)
2. Planula larvae in the life cycle. 

1. Evolution of epithelium - allows movement. 
• Sheets of cells with basal side (interacting with secreted basal lamina) and Apical side (with microvili to interact with fluids from the lumen. 
2. Body Axis - with oral and aboral side 

diploblastic construction held together by mesoglea (thin collogen layer) 

Medusa - Produces Egg and sperm to create planula larva which becomes 

Polyp - an upside down medusa - asexulal reproduces into multiple clones in medusa form