Sponges and Cnidarians

Sponges Phylum Porifera “Pore bearing”

Defining Characteristics sessile – remain attached to single place as adults. No mouth or gut, no muscles, no nervous system. No tissues or organ systems. Collection of specialized cells. Could run through a blender, cells would re-assemble to make new sponge.

Body Plan osculum Body Plan choanocyte Epidermal cell Archaeocyte or amoebocyte pore spicule

Spicules

Feeding: How do sponges get food and digest it? Filter feeders. Flagella (tails) whip around, making currents that draw water in through pores. Archaeocytes pick up and digest bits of dead animal and plant material (detritis) from incoming water.

Respiration: How do sponges exchange oxygen and carbon dioxide? Oxygen in water diffuses into cells, carbon dioxide in cells diffuses out into water. Diffusion = movement of molecules from area of high concentration to low

Nutrients carried by archaeocytes. Circulation: How do sponges transport oxygen, carbon dioxide, and nutrients to wherever they are needed? Oxygen and carbon dioxide carried by diffusion and water currents created by flagella. Nutrients carried by archaeocytes.

Excretion: How do sponges get rid of waste products? Passes from cells into central cavity, carried out osculum (opening at top) by water currents.

Response: What kind of nervous system do sponges have? No brain, no nervous system, no senses Very basic response, all “automatic”

Asexually by budding. A piece of sponge breaks off and grows into REPRODUCTION Asexually by budding. A piece of sponge breaks off and grows into new sponge.

Asexually by budding. A piece of sponge breaks off and grows into REPRODUCTION Asexually by budding. A piece of sponge breaks off and grows into new sponge. Sexually. Sponges makes both sperm and eggs. Sperm released into water, where taken in by another sponge. Sperm fertilizes egg inside sponge. Larvae grow and are carried away by water currents.

Mutualism = relationship where both benefit. Ecology: How are sponges interconnected and interdependent on their environment? Sponges contain photosynthetic bacteria and algae, which provide food and oxygen for sponge. Sponge provides shelter. Mutualism = relationship where both benefit. Sponges provide shelter for snails, shrimp, sea stars, and other small sea animals.

corals jellyfish Cnidarians hydra Sea anemone Sea pens

Jellyfish, sea anemones, coral, hydra, sea pens Defining characteristics: What animals are classified as cnidarians? What do they have in common? Jellyfish, sea anemones, coral, hydra, sea pens Soft bodied and carnivorous Have tentacles with stinging cells (nematocysts)

Cnidarian Body Plan Radial symmetry Central mouth surrounded by tentacles Body wall surrounds gastrovascular cavity (digestive chamber) 2-way digestive tract: Food and waste go through same opening.

Nematocysts: Stinging Cells

Feeding: How do cnidarians get food and digest it? Use nematocysts to sting and paralyze prey. Tentacles pull prey into mouth. Digested in gastrovascular cavity.

Respiration: How do cnidarians exchange oxygen and carbon dioxide? Diffusion between cells and water outside and in gastrovascular cavity. No cells more than a few centimeters away from water.

How does diffusion work? Oxygen in water diffuses into cells, carbon dioxide in cells diffuses out into water. Diffusion = movement of molecules from area of high concentration to low

Diffusion through water in and out of cells. Circulation: How do cnidarians transport oxygen, carbon dioxide, and nutrients to wherever they are needed? Diffusion through water in and out of cells.

Excretion: How do cnidarians get rid of waste products? Diffusion through cell walls into gastrovascular cavity, then out mouth/anus into surrounding water.

Response: What kind of nervous system do cnidarians have? No brain; only a network of interconnected nerve cells (nerve net) Also have eyespots and other sensory cells.

Reproduction: How do cnidarians reproduce? Stage 1: Medusa is motile (can move around). Reproduces sexually. Males and females release sperm and egg into water. Fertilization happens in water. Stage 2: Fertilized egg grows into larva, which turns into polyp. Stage 3: Polyp is sessile (stays in one place like plant). Reproduces asexually by budding.

Ecology: How are cnidarians interconnected and interdependent on their environment? How are coral reef ecosystems endangered? Most corals contain photosynthetic algae that provide food for coral. Coral provides shelter for algae. Coral reefs endangered by human activity: divers, sediment from industry and farming, overfishing. Global warming may also be causing ocean temperatures to rise, killing the algae inside corals. This causes bleaching; they turn pale and die.

Coral Bleaching

Coral Reefs with Severe Bleaching

Why are coral reefs important? Among oldest and most diverse of Earth’s ecosystems. “Rainforests of the sea” Breeding ground for many fish and other marine life. Food, jobs for millions of people. Billions of dollars each year from tourism. Protect shorelines from waves, storms, floods.

Videos Sponges http://www.youtube.com/watch?v=laJgUrSsO_k Sea pens http://www.youtube.com/watch?v=kthxHa3Hats Giant jellyfish http://www.youtube.com/watch?v=u0I-3wkH37w

Questions?