Question | Answer |
Annelids (A nuh ludz) | – “little rings”
– tube shaped bodies that are divided into many segments
– setae (SEE tee) bristle like structures on the outside of each body segment, they help it move and “sense” the environment |
Segmented Worms | bilateral symmetry
a body cavity that
holds organs
2 body openings (mouth & anus)
can live in freshwater,
salt water, & moist soil
EX: earthworms, marine worms and leeches are annelids
(segmented worms) |
Earthworm Dissection Video | http://www.youtube.com/watch?v=u9HHS1uPFSo |
Digestion & Excretion | It takes soil into it’s mouth.
This goes to the crop – a sac used for storage.
Behind the crop is the gizzard – a muscular structure which grinds the soil and the bits of organic mater.
This ground up matter passes to the intestines where the organic m |
earthworms | The taking in of soil to get food helps provide spaces for air and water to flow through the soil and mix the soil ! This is good for the soil.
Their wastes pile up at the openings to their burrows – these piles are called castings.
Castings help |
circulation | closed circulatory
system
2 blood vessels:
one along the top
and one along the
bottom they meet in
the front
5 heart-like “aortic arches”
these pump blood
smaller vessels go into each body segment |
circulation | Try this quiz at this link:
<a href="http://www.softschools.com/quizzes/biology/earthworm_circulatory_system/quiz5662.html">Earthworm Circulatory System</a>
when you see it click on Earthworm Circulatory System Quiz - Soft Schools
then
click on |
respiration | No gills or lungs !!
Oxygen and Carbon-dioxide exchange through their skin. (it is covered with a thin watery mucus)
**Never touch an earthworm with dry hands.
**Never remove their thin mucus layer. |
nerve response | Earthworms have a small brain in their front segment.
Nerves in each segment join to form the main nerve cord that connects to the brain.
They respond to light, temperature, & moisture. |
reproduction | Earthworms are hermaphrodites.
Like the sponge it makes both sperm and eggs, but it can’t fertilize its own eggs.
It has to receive sperm from another earthworm to reproduce. |
Marine Worms- Polychaetes | More than 8000 species.
(PAH lee keets)
They float, burrow, build structures, or walk along the ocean floor.
Some can produce their own light. |
polychaete | Some can live 540m deep.
like earthworms, they have segments
but their setae occur in bundles
(polychaete means “many bristles” |
Christmas tree worm | This sessile, bottom dwelling polychaete, the Christmas tree worm has special tentacles that exchanges oxygen and carbon dioxide as well as
gather food. |
bristleworm | Free-swimming polychaetes, like this bristleworm have a head with eyes, a tail and parapodia.
(per uh POH dee uh)
These are paired, fleshy outgrowths on each segment that help it move and get food. |