Porifera and Cnidarians

1. Porifera and Cnidarians Vineet, Shiv, Kevin, Silas

2. Germ Layers Germ layers a group of cells formed when the embryo is being developed. All animals more complex than porifera have three or more primary germ layers. Porifera Cnidaria Cnidarians mostly have two germ layers, an endothermic and an ectodermic germ layer • Porifera have no germ layers

3. Symmetry Porifera Cnidaria Cnidarians are radially symmetric • Not symmetric

4. Coelom A coelom is a fluid filled body cavity that is usually in the middle germ layer or mesoderm. The coelom allows the internal organs to develop independently of the body wall. Porifera Cnidaria • Both porifera and cnidarians are acoelomates or don’t have coeloms • This means that the organs are subjected to crushing forces underwater

5. Digestive Tract Porifera Cnidarians Cnidarians have a gastrovascular cavity for digestion which helps the organism digest and distribute nutrients and particles throughout the body • These organisms have no digestive tract

6. Cephalization Porifera Cnidaria These organisms have a small degree of cephalization although they are radial symmetric because they have a head and concentrated neural and photoreceptive cells • They have no cephalization because they have no nervous tissue or head

7. Segmentation Porifera Cnidaria None • None Neither one of these phyla are segmented

8. Skeleton and appendages Porifera Cnidaria Cnidarians have a hydrostatic skeleton which help the organism contract and retract against the gastrovascular cavity They have some oral appendages by the mouth to help it feed. • Porifera have an exoskeleton that is made from calcium carbonate which help defend them from predators. • They have no appendages at all

9. Circulatory System Porifera Cnidaria Cnidarians do not need a circulatory system because all of their cells are already in contact with water, which contains all the nutrients they need. • Porifera do not have circulatory systems. By beating their flagella, they cause water to flow through the animal.

10. Respiratory System Porifera Cnidaria Cnidarians absorb oxygen and release carbon dioxide into the surrounding water through their cell layers. They do not have distinct respiratory organs. • Also does not have a respiratory system. The sponge’s cells absorb oxygen through diffusion from the water flow system.

11. Reproduction Porifera Cnidaria Cnidarians can undergo both asexual and sexual reproduction. Asexual reproduction results in identical clones through budding. • Pieces of sponge are able to respawn into whole new sponges. Asexual reproduction also occurs through budding. Each bud develops into a new sponge.

12. Fin