Cylindrical in shape

This is more primitive

May be divided into a left and a right side

More modern

    Dorsal

 (tail)   Posterior                      Anterior (head)

     Ventral

The innermost of the three primary germ layers of an animal embryo, developing into the gastrointestinal tract, the lungs, and associated structures.

AKA hypoblast

"Warm-blooded"

Animals that maintain a constant, homeostatic body temperature using heat generated by the metabolism.

Mainly mammals and birds.

"Cold Blooded"

Animals that regulate their body temperature by absorbing heat energy

1) Acoelomate

2) Pseudocoelomate

3) Eucoelomate

1) Protostomate

2) Deuterostomatee

1. herbivore
2. carnivore/ predator
3. omnivore
4. scavenger
5. parasite
6. filter feeder

Protonephridia - Invertebrate organ for excretion. Flame cells in flat worms

Nephridia 

Kidneys 

Sponges

• Collar Cells - function in filter-feeding and reproduction. Creates a negative pressure system within the sponge
• Amoebocyte - function in filter-feeding digestion, spicule formation, and reproduction
• Spicules - skeletal elements of a sponge. Defense. Calcium carbonate, silicates, or spongin
• Secile
• Budding and fragmentation
• No nervous system

• Hydrozoa - Only has a polyp stage
• Scyphozoa - Only has a medussa stage
• Anthozoa - Lack the madussa stage

• Jellyfish, Hydra, Portuguese man-of-war, sea anemones, corals
• Radial symmetry, tissues and some organs
• Some have two stages: Polyp, medusa
• cnidocytes for defense
• use cnidocytes and tenticles to ingest food into the gastrovascular cavity... no true digestive system
• Only swim during medusa stages
• Medusa- sexual
  Polyp- asexual 

• Planarians (flat-worms), Schistosoma (flukes), Taenia (tapeworms)
• Bilateral, acoelomates, free-living and parasitic species
• Parasitic forms have a scolex (a head), and their body has proglottids or segments 
• gastrovascular cavity for food, with a pharynx as the entry point, and flame cells as the excretatory area.
• cicrcular and longitudenal muscles
• for defense, parasytes have cuticles, a waxy coating.
• hermaphroditic sexual
  Asexual when head, tail, etc. cut off
• Cephalization - head with a brain and sensory organs up front  

• Turbellaria
• Trematoda
• Cestoda

• roundworms, soil nematodes, Ascaris (human round worms), pinworms, hookworms, heartworms, Trichinella
• Free-living and parasytic
• bilateral symmetry, pseudocoelomates
• complete digestive tract with mouth and anus
• longitudenal muscles only
• parasitic forms have a cuticle
• mostly sexual with seperate sexes represented

Relay stations in the CNS

In some lower systems, ganglia is the brain

In sponges...

coanocytes = collar cells, inner lining. create the current that sucks water in

amoebocytes = function in digestion and function in reproductionl