Annelida

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Annelida

• Segmented Worms

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N0- not that kind of worm!
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Common Examples

• Earthworms

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Common Examples

• Bristle Worms

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Common Examples

• Feather Duster Worms

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Common Examples

• Tube Worms

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Common Examples

• Tube Worms

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Common Examples

• Leeches

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• Rag Worm

How would you like to run into the jaws of this
guy!
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(No Transcript)
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Characteristics

• Segmentation
• Cephalization
• Bilateral Symmetry
• Coelomates
• One way digestive tract
• Both Filter Feeders and Predators
• Asexual and Sexual Reproduction
• Water and Land Examples

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Segmentation

• Each segment repeats
• Very efficient design.
• Some are specialized
• Digestion, reproduction,excretion, etc.

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Definite Head End
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Annelida has Bilateral Symmetry
Yes, Symmetric
No, not Symmetric
No, not Symmetric
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Section 27.2 Summary pages 728-733
Body Structure

• The basic body plan a tube within a tube

• internal tube suspended w/in coelom digestive
  tract.

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Phylum Annelida

• Hydrostatic skeleton
• Fluid pressure in coelom provides support
  locomotion
• Circular muscles
• Longitudinal muscles
• Peristaltic locomotion squeeze, relax, squeeze!

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Section 27.2 Summary pages 728-733
Body Structure

• SETAE tiny bristles on each segment

• help move
• anchors body in soil so each segment can move
  the animal along

Setae
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Phylum Annelida

• Setae (bristles) of chitin a carbohydrate
• Chitin forms the exoskeleton in insects, shrimp,
  crayfish, etc.
• anchors for earthworm
• paddles for polychaete
• Enlarged as jaws in leeches, some polychaetes

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Section 27.2 Summary pages 728-733
Body Structure

• distinguishing characteristic is that bodies are
  divided into ringed segments

• In most species, segmentation continues
  internally as each segment is separated from the
  others by a body partition.

Segments
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Section 27.2 Summary pages 728-733
Body Structure

• Each segment has its own muscles, allowing
  shortening and lengthening of the body.

• Segmentation also allows for specialization of
  body tissues.

• Certain segments have modifications for functions
  such as sensing and reproduction.

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Section 27.2 Summary pages 728-733
Nervous system

• Segmented worms have simple nervous systems in
  which organs in anterior segments have become
  modified for sensing the environment
  cephalization

• Some sensory organs are sensitive to light, and
  eyes with lenses and retinas have evolved in
  certain species.

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Nervous system

• In some species there is a brain located in an
  anterior segment.

Setae

• Nerve cords connect the brain to nerve centers
  called ganglia, located in each segment.

Brain
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Phylum Annelida

• Closed circulatory system
• Multiple hearts
• Hemoglobin not in blood cells
• reddish-pink color
• Blood carries O2 to and CO2 from body cells
• flow through vessels to reach all parts of the
  body
• must live in water or in wet areas on land
  because they exchange gases directly through
  their moist skin like your lungs

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Section 27.2 Summary pages 728-733
Digestion and Excretion

• complete internal digestive tract
• length of body
• Nutrients diffuse to blood
• Transported to all cells

• Food gt mouth gt crop gtgizzard gt gut gtanus

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Section 27.2 Summary pages 728-733
Digestion and Excretion
Gizzard
Crop

• GIZZARD
• a muscular sac
• Contains hard particles to grind soil and food
  before they pass into intestine/gut

Mouth
Circulatory System
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Section 27.2 Summary pages 728-733
Excretion

• have two nephridia in almost every segment.
• Special cells that collect waste and transport it
  through the coelom and out of the body.

Nephridia
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Section 27.2 Summary pages 728-733
Reproduction

• Earthworms and leeches are hermaphroditic
• exchange sperm.
• forms a capsule for the eggs and sperm.
• The eggs fertilized in capsule, then it slips off
  the worm and left in soil
• 2-3 weeks, young worms emerge from the eggs.

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Section 27.2 Summary pages 728-733
Reproduction in Bristleworms

• separate sexes and reproduce sexually.

• eggs and sperm are released into seawater and
  fertilize there external fertilizaton

• larvae hatch in sea
• become part of the plankton important part of
  food chain

• Eventually settles to the bottom to live

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Section 27.2 Summary pages 728-733
CLASSES OF ANNELIDA

• ClassOligochaeta - earthworms
• Class Polychaeta - bristleworms
• Class Hirudinea - leeches

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Section 27.2 Summary pages 728-733
Class Oligochaeta Earthworms

• most well-known annelids
• Easily seen by most people.

• burrows through soil
• Loosens and aerates soil
• Feces castings fertilizer
• Ecologically very important
• Possible human food source protein

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Section 27.2 Summary pages 728-733
Class Polychaeta Bristleworms

• Polychaete means many bristles
• Most body segments have many setae

• has a head with well-developed sense organs,
  including eyes.

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Section 27.2 Summary pages 728-733
Class Polychaeta Bristleworms

• have parapodia, (paired feet)
• can be used for swimming or crawling over corals
  and bottom of sea.

• Parapodia also function in gas exchange.

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Section 27.2 Summary pages 728-733
Class Hirudinea Leeches

• segmented worms with flattened bodies
• usually no setae

• Many are parasites
• suck blood or other body fluids from hosts
  (ducks, turtles, fish, and humans).

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Section 27.2 Summary pages 728-733
Hirudinea Leeches

• Front and rear suckers for attachment

• saliva contains
• anesthetic chemicals
• Anticoagulants prevent clotting of blood

• can ingest 2 to 5 times its weight in 1 meal.

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Section 27.2 Summary pages 728-733
Origins of Segmented Worms

• Annelids probably evolved in the sea, perhaps
  from larvae of ancestral flatworms.

• Tubes constructed by polychaetes are the most
  common fossils of this phylum.
• Some of these tubes appear in the fossil record
  as early as 540 million years ago.