Invertebrates Sponges & Cnidarians

Sponges Kingdom: Animalia Simplest invertebrates Phylum: 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 live 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 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 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