CNIDARIANS WORMS CNIDARIANS HAVE DIFFERENT BODY SYSTEMS Cnidarians

CNIDARIANS & WORMS • CNIDARIANS HAVE DIFFERENT BODY SYSTEMS – Cnidarians are invertebrates (jelly fish, coral, hydras, sea anenome) Most feed on plankton, fish, & clams. – Cnidarians have tentacles with specialized stinging cells to capture prey. Stinging cell has a nematocyst (like a spring loaded dart that shoots out & releases poison). • ANIMALS HAVE DIFFERENT BODY PLANS • MOST WORMS HAVE COMPLEX BODY SYSTEMS

• CNIDARIANS Made of layers of tissues ( central opening to take in food & remove waste); have a simple nervous system to respond to their environment. • Reproduce asexually by buds released in the water; Sexual reproduction by sperm carried to egg in female releases free swimming larva

Animals: different body plans • Most cnidarians have radial symmetry (organized around a central point) • Radial plan lets sessile organism to capture food from any direction. • Most animals have bilateral symmetry (only 1 way to divide into 2 equal halves) • Animals head at forward end where mouth is. Animals moves forward, head first in search for food. Food enters one end, nutrients absorbed and waste released at other end; works well for mobile organisms. • Jellyfish larva settle on ocean floor & grow to sessile polyps release buds (medusas-adult jelly)

WORMS • Some worms have simple bodies, others have welldeveloped bodies. • Worms have tube shaped body with bilateral symmetry. • Take in oxygen dissolved in water through their skin! • Must live in moist environments; many live in water

SEGMENTED WORMS • Segmented worms have bodies divided into compartments. Called annelids (ringed animal). • Earthworms(type of annelid) pass soil through digestive system to digest pieces of plant & animal matter from soil & excrete leftover waste. This adds nutrients and oxygen to the soil. • Earthworm also has nervous(sense light & vibrations in soil) & circulatory system (several hearts). Some annelids are asexual. But Earthworms have male & female organs; 2 worms exchange sperm, fertilize & release eggs which hatch into larva

FLATWORM & ROUNDWORMS • Flatworms are the simplest worms; they absorb nutrients directly thru their skin. • Many flatworms live as parasites, feeding off other organisms (tapeworm lives in digestive tract of humans/animals to absorb their nutrients, doesn’t need a digestive tract of its own) • Roundworms found everywhere on Earth • Roundworms are more complex, have muscles to move with, Nervous system & Digestive system. • Some roundworms are important decomposers on land in water.