Phylum Annelida

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Phylum Annelida

• Segmented Worms
• Earthworm

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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.

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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 earth tones such as
  brown, tan, etc. It can be up to eight feet in
  length!

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Body Cavity

• Coelomate

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Do You Have A Cavity???
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Muscular-Skeletal

• A earthworm does not have a skeleton. It has
  bristles on each segment called setae that help
  the earthworm move.
• Rear Anchor? Elongation ? Front Anchor? Pull

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Muscular-Skeletal

• The earthworm has two sets of muscles one that
  makes it long and thin and one that makes it
  shorter and fatter.

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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 pharynx for the 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.

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Digestion (cont.)
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• Virtual Worm Digestion
• worm systems

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Nervous System

• A earthworm
• has a
• nervous system
• with a simple
• brain and
• ventral nerve
• cord.

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Circulation

• A earthworm has blood and blood vessels with
  multiple (5) hearts.

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Respiration

• A earthworm has no respiratory organ. It takes in
  oxygen directly through its skin and gives off
  carbon dioxide. Its skin is always moist.

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Reproduction

• A earthworm has both sperm and eggs within its
  body and reproduces sexually. However, the eggs
  must be fertilized by the sperm of another worm.

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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
  clitella and exchanging sperm, and then they
  separate. 

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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.

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Mating of 2 Earthworms
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Reproduction
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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.

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Symmetry

• A earthworm has bilateral symmetry.

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Helpful Earthworms!

• Did you know that Earthworms are a gardeners best
  friend?
• 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

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Parasitic Annelids????
Yepyou guessed it LEECHES!
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Fun with Leeches!

• 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!

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