Download Phylum Annelida (segmented worms)

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.
 A 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.
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Rear Anchor→ Elongation → Front Anchor→ Pull
Earthworm movement
Muscular-Skeletal
 The
earthworm has two sets of muscles;
one that makes it long and thin and one
that makes it shorter and fatter.
Digestion
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A earthworm has a digestive system. It eats dirt,
digesting the plant and animal matter in the dirt
and then eliminates the rest. - mouth takes in
food
a pharynx throat of earthworm,
A esophagus to pass food to crop
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 waste to come out.
Digestion (cont.)
Nervous
System
A
earthworm
has a
nervous system
with a simple
brain and
ventral nerve
cord.
Circulation
A
earthworm has blood and blood
vessels (dorsal & ventral) with multiple
(5) hearts.
Respiration
A
earthworm has no respiratory organ. It
takes in oxygen directly through its skin
and gives off carbon dioxide (diffusion). Its
skin is always moist.
Reproduction
A
earthworm has both sperm and eggs
within its body (Hermaphrodite) and
reproduces sexually. However, the eggs
must be fertilized by the sperm of another
worm.
Reproduction (cont.)
 Earthworms
are hermaphrodites with
complex male and female reproductive
organs present in each individual, but they
cross fertilize.
 Two earthworms mate by attaching at their
clitellum 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 which are produced in ovaries
and then the stored sperm from special
reproductive pores and then slips off the
worm's head.
 The embryos develop within the cocoon.
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.
 External anatomy of Earthworm
Symmetry
A
earthworm has bilateral symmetry.
Helpful Earthworms!
 Did
you know that
Earthworms are a
gardeners best
friend?
Earthworms…
Break up/aerate soil
Helps water flow in soil
Worm feces contain
bacteria that help return N
to soil
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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.
More leech facts
 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.
 The nearest relatives of leeches are
earthworms.
 Leeches can bite through a hippo's hide!