Sponges and Cnidarians Animals unit

 Mostly live in oceans, but also in freshwater rivers and lakes  Adult sponges are attached to hard surfaces underwater.  Water currents bring food and oxygen  Currents carry away waste.  Currents help transport young to new places to live. Sponges

 Sponges are invertebrate animals that usually have no body symmetry and never have tissues or organs.  Looks like a tube with pores.  Phylum to which they belong means “having pores.”  Most sponges have spikes. (as sharp as needles)  Spikes support its body keeping it upright.  Spikes help sponge protect itself. Body structure

 Sponge eats tiny single-celled organisms.  Sponge filters organisms from the water passing through.  The collar cells that line the central cavity trap the organisms  The jelly-like cells inside the sponge then digest the food.  Sponge gets oxygen from water. It is filtered through the cells. Obtaining food and oxygen

 Cnidarians (ny dehr ee unz) are invertebrates that have stinging cells and take food into a central body cavity  Cnidarians use stinging cells to capture food and defend themselves. Cnidarians

 Two different body plans, both have a central hollow cavity and tentacles that sting.  The vase-shaped body is called POLYP. The polyp’s mouth opens at the top and its tentacles spread out from around the mouth. They are attached to underwater surfaces.  The bowl-shaped body is called MEDUSA. Has a life of swimming. Mouths that open downward and tentacles that trail down.  Some cnidarians go through a polyp stage and a medusa stage. Others are just one or the other. Body structure Polyp Medusa

 Both types obtain food the same way.  Cnidarians use stinging cells to catch the animals they eat.  When the stinging cell touches prey, the threadlike structure explodes out of the cell and into the prey.  Some stinging cells release venom.  When the prey is helpless, the cnidarian uses its tentacles to pull the prey into its mouth. From there, it passes into a hollow cavity, where it is digested.  Undigested food is expelled through the mouth. Obtaining food

 Unlike adult sponges (attached to hard surface), many cnidarians can move to escape danger.  Jellyfish swim  Hydras turn slow somersaults  Sea anemones stretch out, shrink down, bend slowly from side to side, and move slowly from place to place. Movement Jellyfish Anemone Hydra

Life Cycle

 Colony is a group of many individual animals.  Coral reef is built by cnidarians. At the beginning of its life to polyp attaches to a solid surface (ship, rock, or shells).  Coral reef are home to more species of fishes and invertebrates than any other environment on Earth. Life in a Colony