Sponges & Cnidarian Chapter 35

Sponges Invertebrates - animals without back bones. Simplest of the multicellular animals. No organ system. Kingdom: animalia Phylum: porifera

Movement Holdfast - root-like - attach the sponge to rocks. Adult sponges are sessile - unable to move.

Structure : Skeleton Spongin Spicule – hard, spike-like, particles of calcium carbonate of silicon dioxide that make up a sponges skeleton

Structure Collar cells-create a current of water through the sponge. Thousands of pores let water flow through it continually. Water exits through the osculum – opening at the top of the sponge.

Filter Feeding Obtain nourishment and oxygen from this water. Engulfed by collar cells and passed to amebocytes which distribute the nutrients to the rest of the body.

Reproduction Budding Gemmules Regeneration Sexual reproduction

Sexual Reproduction Sperm released Egg is fertilized Larva form and leave the sponge. Larva settles and attaches to an object. Larva grows into an adult sponge.

Examples of cnidarians Jellyfish Sea anemones Coral animals

Characteristics of Cnidarian Invertebrates Radial symmetry Tentacles with stinging cells.

The two different forms of a Cnidarian body Bell shaped Specialized for swimming Vase shaped Sessile existence

Movement Most cnidarians are slow-moving or sessile Found on shallow ocean floors, the bottom of ponds or drifting about in water currents.

Characteristics Gastrovascular cavity center of the body Hollow gut One opening surrounded by tentacles

Feeding and Defense Cnidocytes – cells found on tentacles used for defense & capturing prey. Nematocyst – organelle in cnidocyte which can eject a filament with poison.