SPONGES AND CNIDARIANS

Sponges

•Phylum Porifera•“Pore bearing”

• 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.

Defining Characteristics

BODY PLANosculum

choanocyte

Epidermal cell

Archaeocyte or amoebocyte

pore

spicule

Body Plan

Spicules

• 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.

Feeding: How do sponges get food and digest it?

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

– Oxygen and carbon dioxide carried by diffusion and water currents created by flagella.

– Nutrients carried by archaeocytes.

CIRCULATION: HOW DO SPONGES TRANSPORT OXYGEN, CARBON DIOXIDE, AND NUTRIENTS TO WHEREVER THEY ARE NEEDED?

Passes from cells into central cavity, carried out osculum (opening at top) by water currents.

EXCRETION: HOW DO SPONGES GET RID OF WASTE PRODUCTS?

No brain, no nervous system, no senses Very basic response, all “automatic”

RESPONSE: WHAT KIND OF NERVOUS SYSTEM DO SPONGES HAVE?

REPRODUCTION

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

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.

– 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.

ECOLOGY: HOW ARE SPONGES INTERCONNECTED AND INTERDEPENDENT ON THEIR ENVIRONMENT?

CNIDARIANSjellyfish

Sea anemonehydra

corals

Sea pens

– Jellyfish, sea anemones, coral, hydra, sea pens

–Soft bodied and carnivorous

–Have tentacles with stinging cells (nematocysts)

DEFINING CHARACTERISTICS: WHAT ANIMALS ARE CLASSIFIED AS CNIDARIANS? WHAT DO THEY HAVE IN COMMON?

CnidarianBody 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

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.

– 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.

ECOLOGY: HOW ARE CNIDARIANS INTERCONNECTED AND INTERDEPENDENT ON THEIR ENVIRONMENT? HOW ARE CORAL REEF ECOSYSTEMS ENDANGERED?

CORAL BLEACHING

CORAL REEFS WITH SEVERE BLEACHING

• 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.

WHY ARE CORAL REEFS IMPORTANT?

VIDEOS

http://www.youtube.com/watch?v=laJgUrSsO_k

Sea pens

http://www.youtube.com/watch?v=kthxHa3Hats

Sponges

Giant jellyfish

http://www.youtube.com/watch?v=u0I-3wkH37w

Questions?