| A | B |
|---|
| To which phylum do sponges belong? | Phylum Porifera |
| Why is "phylum Porifera" appropriate for sponges? | The name means "pore-bearers" which describes sponges well. |
| Why are sponges classified as animals? | They are multicellular, heterotrophic, have no cell walls, and contain a few specialized cells. |
| What does it mean when it says sponges are asymmetrical? | Sponges have no front or back ends, and no left or right sides. |
| What are choanocytes? | They're specialized cells that use flagella to mopve a steady current of water through the sponge. |
| How much water passes through a sponge in a day? | As much as several thousand liters/day. |
| What is an osculum? | It is the large hole at the top of the sponge through which water leaves the sponge. |
| Why is the movement of water through the sponge important? | It provides a simple mechanism for feeding, respiration, circulation, and excretion. |
| What is a spicule? | In harder sponges, the skeleton is made up of these. Spicules are spike-shaped structures made of chalklike calcium carbonate or glasslike silica. |
| What are archaeocytes? | They're specialized cells that move around within the walls of the sponge. |
| What type of digestion occurs in sponges? | Intracellular digestion--it takes place inside the cells. (see 665) |
| How does oxygen get to the sponge's cells? | As water moves through the body cavity, oxygen that's dissolved in the water diffuses to the cells. |
| How are wastes removed from the sponge? | As water moves through the body cavity, carbon dioxide and other wastes, such as ammonia, diffuse into the water and exit the sponge. |
| How do sponges protect themselves? | They produce toxins that make them undesirable asw food or poisonous to predators. |
| How do sponges reproduce? | They reproduce sexually or asexually. (see diagram on 666) |
| What is internal fertilization? | This is when eggs are fertilized inside the body, as they are in sponges. |
| What is a sponge larva? | It's an immature stage of an organism that has an appearance different from the adult. These larvae are motile. |
| What are gemmules? | They're a group of archaeocytes surrounded by a tough layer of spicules; they're produced by some sponges. |
| Compare sexual & asexual reproduction in sponges. | Sexual: joining of haploid gametes produced in meiosis (offspring doesn't resemble parents). Asexual: cells of the bud or gemmule (diploid) divide repeatedly by mitosis, producing growth (offspring are genetically identical to parents). |
| Where do most sponges live? | On the sea floor |
