Transcript Phylum Annelida - Solon City Schools

Phylum Annelida
Segmented Worms
Earthworm
Characteristics of Annelids
• Earthworms are the most highly developed
worms.
• They are divided into segments or parts.
• They are found in salt and fresh water as
well as in the soil.
Characteristics of Annelids
• Earthworms are helpful to man as bait for
fishing and more importantly, because
they loosen the soil for roots to grow.
• There are 2700 species of earthworms.
• An earthworm is generally earthtones such
as brown, tan, etc. It can be up to eight
feet in length!
Body Cavity
• Coelomate
Muscular-Skeletal
• A earthworm does not
have a skeleton. It has
bristles on each segment
called setae that help the
earthworm move.
• The earthworm has two
sets of muscles; one that
makes it long and thin
and one that makes it
shorter and fatter.
•
Rear Anchor→ Elongation →
Front Anchor→ Pull
Digestion
• A earthworm has a digestive system. It eats dirt,
digesting the plant and animal matter in the dirt
and then eliminates the rest.
• a mouth called a prostomium for the food to go
in,
• A pharynx and esophagus for food to go down
• A crop to store the food in,
• a gizzard that grinds the food down,
• intestines for the food to pass through and take
out nutrients
• an anus for the food to come out.
Digestion (cont.)
• worm systems
• Earthworm Systems
• http://www.naturewatch.ca/english/wormw
atch/virtual_worm/Digestion.htm
Nervous
System
• A earthworm
has a
nervous system
with a simple
brain (cerebral
ganglion)and
ventral nerve
cord.
Circulation
• A earthworm has blood and blood vessels
with multiple (5) hearts. (Called “aortic
arches”)
Annelids have a “Closed”
Circulatory System
• The blood stays in vessels and basically
travels in a loop…
• Hearts pump blood into the Dorsal blood
vessel (to body) and back to heart in the
ventral blood vessel
Respiration
• A earthworm has no respiratory
organs.
• It takes in oxygen directly through its
skin and gives off carbon dioxide.
• Its skin is always moist.
Reproduction
• A earthworm has both sperm and eggs
within its body and reproduces sexually.
– This is called ______________
• hermaphrodites
– However, the eggs must be fertilized by the
sperm of another worm.
Reproduction (cont.)
• Yes, Earthworms are hermaphrodites,
but they still must cross-fertilize to
produce offspring
• Two earthworms mate by attaching at their
clitella and exchanging sperm, and then
they separate.
Reproduction (cont.)
• The received sperm are temporarily stored
in sperm receptacles while the clitellum
secretes a mucous cocoon.
• The cocoon slides along the worm, picking
up the eggs and sperm from special
reproductive pores and then slips off the
worm's head.
• The embryos develop within the
cocoon.
• Earthworm - Lumbricus terrestris ARKive - video 09
Mating of 2 Earthworms
Reproduction
Excretion
• A earthworm's wastes help to fertilize the
soil. It gets rid of its wastes through tubes
called nephridia that lead to pores that
allow the wastes out.
Symmetry
• A earthworm has bilateral symmetry.
Helpful Earthworms!
• Did you know that
Earthworms are a
gardeners bestfriend?
• Earthworms…
– Break up/aerate soil
• Helps roots be able to penetrate soil
• Helps water flow in soil
– Worm feces contain bacteria that
help return N to soil
Parasitic Annelids????
Yep…you guessed it…
LEECHES!
Fun with Leeches!
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Leech Facts:
There are 650 known species of leeches.
The largest leech discovered measured 18 inches.
The leech has 32 brains - 31 more than a human.
Not all leeches are bloodsuckers. Many are predators which eat earthworms, etc.
The bite of a leech is painless, due to its own anaesthetic.
The Hirudo leech injects an anti-coagulant serum into the victim to prevent the blood
clotting.
The leech will gorge itself until it has had its fill and then just fall off.
The leech will gorge itself up to five times its body weight.
The first leech was used in medicine about 1000 B.C., probably in ancient India.
In the past, people would stand in the lakes and pools dotted around the country and
when the leeches attached to their legs they would put them in baskets and sell them.
Today the Hirudo leech is an endangered species.
The nervous system of the leech is very similar to the human nervous system and is
of enormous benefit to researchers in their quest for the answers to human problems.
The nearest relatives of leeches are earthworms.
Leeches can bite through a hippo's hide!