Section 24.3: Sponges and Cnidarians

A. Sponges

1. Body Structure Sponges do not develop tissues Sponges do not develop tissues Sponges are asymmetrical Sponges are asymmetrical The tissues normally develop from ectoderm, endoderm, and mesoderm The tissues normally develop from ectoderm, endoderm, and mesoderm There are 2 layers of individual cells with a jelly- like layer between the cells There are 2 layers of individual cells with a jelly- like layer between the cells Epithelial cells cover and protect Epithelial cells cover and protect Collar cells line the inside of the sponge Collar cells line the inside of the sponge They have flagella to help move water. They have flagella to help move water.

2. Feeding and Digestion Filter feeder  gets food by filtering small particles out of the water Filter feeder  gets food by filtering small particles out of the water Sponges can filter as much as 100 L of water per day Sponges can filter as much as 100 L of water per day Nutrients and oxygen are dissolved in the water and enter the pores Nutrients and oxygen are dissolved in the water and enter the pores Nutrients stick to the collar cells Nutrients stick to the collar cells Digestion takes place within each cell Digestion takes place within each cell Sessile  are attached and stay in one place (adult sponges) Sessile  are attached and stay in one place (adult sponges)

3. Support Within the jelly-like layer of 2 cells, are amoeboid cells Within the jelly-like layer of 2 cells, are amoeboid cells Can move and change shape Can move and change shape Involved in digestion, production of sperm and egg, and excretion Involved in digestion, production of sperm and egg, and excretion Also make spicules Also make spicules Spicules  small, needle-like structures made of calcium carbonate, silica, or spongin (protein) Spicules  small, needle-like structures made of calcium carbonate, silica, or spongin (protein)

4. Sponge Diversity 3 classes based on their support systems 3 classes based on their support systems Demospongiae: Demospongiae: Spicules of spongin fibers, silica, or both Spicules of spongin fibers, silica, or both Ex. Bath sponge Ex. Bath sponge Calcarea: Calcarea: Spicules composed of calcium carbonate Spicules composed of calcium carbonate Rough texture Rough texture Hexactinellida: Hexactinellida: Spicules made of silica Spicules made of silica Ex. Glass sponges (look like spun glass) Ex. Glass sponges (look like spun glass)

5. Response to Stimuli Sponges do not have a nervous system Sponges do not have a nervous system The epithelial cells detect external stimuli and respond by closing pores The epithelial cells detect external stimuli and respond by closing pores

6. Reproduction Sponges can reproduce asexually in 3 different ways: Sponges can reproduce asexually in 3 different ways: Fragmentation  a piece of sponge that is broken off develops into a new adult sponge Fragmentation  a piece of sponge that is broken off develops into a new adult sponge Budding  a small growth (bud) forms on a sponge, drops off, and settles into a spot where it will grow Budding  a small growth (bud) forms on a sponge, drops off, and settles into a spot where it will grow Gemmules  seed-like particles that form during droughts or freezing temps Gemmules  seed-like particles that form during droughts or freezing temps contain sponge cells protected by spicules that will survive and grow again when conditions are favorable contain sponge cells protected by spicules that will survive and grow again when conditions are favorable Found in freshwater sponges Found in freshwater sponges

Addition: Sponges can reproduce sexually also Sponges can reproduce sexually also Most are hermaphrodites Most are hermaphrodites Eggs remain within the sponge while the sperm are released into the water Eggs remain within the sponge while the sperm are released into the water Sperm released from one sponge can be carried by the water to the collar cells of another sponge Sperm released from one sponge can be carried by the water to the collar cells of another sponge Collar cells change into specialized cells to carry the sperm and the egg Collar cells change into specialized cells to carry the sperm and the egg After fertilization, a zygote develops into larvae that is free- swimming and has flagella After fertilization, a zygote develops into larvae that is free- swimming and has flagella Larvae will attach to a surface and grow Larvae will attach to a surface and grow

7. Sponge Ecology Spicules and distasteful compounds discourage most predators Spicules and distasteful compounds discourage most predators Sponges can be food for tropical fish and turtles Sponges can be food for tropical fish and turtles Sponges can be habitats for worms, fish, shrimp, and algae Sponges can be habitats for worms, fish, shrimp, and algae Some sponges live on mollusks Some sponges live on mollusks Some sponges can be possible antibiotics, respiratory aids, and gastrointestinal meds Some sponges can be possible antibiotics, respiratory aids, and gastrointestinal meds

Sponges Common Sea Sponge

Common Natural Sea Sponge

Cloud Sponge

Common Sea Sponges

Glass Sponge