Transcript CNIDARIANS - Neshaminy School District / Overview

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; 2worms 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 and in water.