Platyhelminthes and AnnelidaOr Worms

http://www.okc.cc.ok.us/biologylabs/Images/Animal_Images/annelida.jpghttp://www.glogster.com/media/2/3/71/6/3710611.jpg

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Scientific Name

• Platyhelminthes – flat worms

• Annelida – segmented worms

• Nematods – round worms

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Symmetry

• Platyhelminthes – bilateral symmetry along their body

• Annelida – bilateral symmetry along their body

Evolutionary History

• Different phylogenic analysis

• Platyhelminthes – most closely related to Molluscs

• Annelida – most closely related to Molluscs

• Nematods – mostclosely related to Arthropods

Derived Characteristics Platyhelminthes

• Organs and systems• Bilateral symmetry• Gastrovascular cavity• Closed digestive system• Excretory system – protonephridia• Reproductive system – generally

hermaphrodites• Nervous system -- ganglia

http://www.thaigoodview.com/library/contest2551/science04/17/2/ThaiGoodView/platyhelminthes/Platyhelminthes_Planaria_2.gif

Derived CharacteristicsAnnelida

• Division of segments

• Skin-muscle sack is developed

• True gastrovascular cavity with walls

• Respiratory system – gills

• Circulatory system and blood vessels

• Excretory system – metanephridia

• Nervus sytem -- brain

ReproductionPlatyhelminthes

• Sexual reproduction and hermaphrodism

• Cross – fertilization or self – fertilization

• Formation of clitellum

• Fission – Asexual reproduction

• Parthenogenesis – reproduction without fertilization

Annelida

• Fission – Asexual reproduction

• Sexual reproduction - hermaphrodites or gonochorists

• Formation of clitellum

• Copulation of worms

• Transfer of sperm

Life Cycle•Direct or indirect life cycles

•The direct one comes after fission reproduction

•The indirect one comes after sexual reproduction

• Direct cycle – splitting

• Indirect cycle – several stages:

• Egg

• Cacoon

• Larva

• Adulthttp://www.life.umd.edu/biology/faculty/bely/paratomy.gif

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Nervous System

Platyhelminthes• Two nerve knots

ganglia• Two nerve ventral

cords• Branches• There can be eye

spots

Annelida• More complex• Cerebral ganglia

around the mouth• Nerve chain along the

body• Sense organs

Digestive System

Platyhelminthes• Gastrovascular cavity• Closed digestive

system• Mouth, front, middle

intestine, appendix• Eat microorganisms• Parasites

Annelida• Open digestive

system• Mouth, front, middle,

back intestine, appendix, anus

• Eat microorganisms• Parasites

Red Californian Worm• Hybrid of the Eisenia foetida 

• produced in 1956 in the University of California

• Live in the soil

• The best temperatures for reproduction are between 14o C and 17o C

• Eat organic wastes and especially feces

• Produce natural organic fertilizer

• Special farms with Red Californian worms

• Move with parapodi

• The stages of life are egg, cocoon, larva and adult worm

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Medical Leech

• Hirudo medicinalis• May reach 30 centimeters • Lives in fresh water• Reproduces by eggs• Segments without parapods• Sucks blood• Used for draining blood and dissolving

blood clotshttp://static.open.salon.com/files/leech1234463201.jpg

Taenia Solium or Pork Tapeworm • parasites

• found everywhere on land and in water where vertebrates live

• adult tapeworms live in vertebrates intestines of humans and animals

• They can grow from 1mm to 15 m, he tapeworm grows to a length of 2 to 7 meters in 5 to 12 weeks.

• attached- absorb the nutrients released by digestion in the hosts intestines, through their body wall

• enter the body- serious problems with the vertebrates in the human; animal body

• armed with sackers and hooks which the worm uses to attach itself to the inner organs and moves by that way

Human uses/interactions with wormsa) Their parasitic life usually makes the host’s

organism ill

b) At the end of the food chain → the worms are indirectly involved in producing the food that humans eat and from which people take the minerals and vitamins needed for the proper

function of their organisms.

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