Invertebrates Sponges & Cnidarians Sponges

 Kingdom: Animalia – Sub Phylym: Porifera (sponges)  Simplest invertebrates  Asymmetrical (no symmetry!)  No tissues, gut or nerves How Do Sponges Eat?

 Filter feeders: feed on tiny plants and animals  Water carries food into the sponge through pores (ostia) – Ostia: holes on the outside of the body  Inside the sponge, collar cells remove food from the water – Collar cells: special cells that line the central cavity of the sponge; they digest food  The water exits through an osculum – Osculum: hole at the top of the sponge Sponge Anatomy

• Where does the water enter?

• Where does the water exit?

• What structure on the collar cells pushes the water up? Body Part Abilities

 If a part of a sponge is broken off, the missing part can regenerate, or grow back  If a sponge is broken into pieces, new sponges could form from each piece  If you force a sponge body through a strainer, the separated cells could come back together and reform the same sponge! Kinds of Sponges

 All are in the water (most in salt water)  Come in different shapes/sizes  Most sponges have a skeleton made of hard fibers called spicules  Grouped by their type of skeleton – Barrel sponge – Tube Sponge – Finger Sponge – Vase Sponge Cnidarians

 Pronounced “nigh-dare-e-ins”  Kingdom: Animalia – Sub Phylum: Cnidaria  Invertebrates that have stinging cells  More complex than sponges – Have complex tissues, a gut & simple nerves  Include: jellyfish, hydrozoa, sea anemones and coral Two Body Forms

 Cnidarians have ONE of the two body forms: – Medusa: swim through the water – Polyp: attach to a surface  Some change forms at different times in their life Special Cells

 All cnidarians have tentacles covered with stinging cells – Nematocysts: stinging cells that release spears into an organism when it brushes the tentacles  Some can release poison  Used for protection and to catch food Kinds of Cnidarians

**We split them into four classes:

Kingdom: Animalia Sub Phylum: Cnidaria Class: Hydrozoa Scyphozoa Anthozoa Cubozoa Hydrozoans

 Hydra, Portuguese Man-o’War  Hydra are always polyps (attached)  Live in fresh and salt water  Many live in colonies Scyphozoans

 Jellyfish  Catch other inverts and fish in tentacles  Spend most of their life as a medusa Anthozoans

 Sea Anemones and Corals  Spend their lives as polyps  Often brightly colored  Live in colonies Cubozoans

 Are square shaped when viewed from above  Resemble true jellyfish  Have well developed eyes  Are one of the most deadliest animals in the ocean