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Metameric segmentation
all segments are identical
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Setae
tiny, chitinous bristles that help anchor segments during movement
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Hydrostatic skeleton
can make themselves rigid with muscle contraction
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Septum
seperates segments and allows for very precise movement
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Parapodia
paired appendages in polychaeta
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Clitellum
band like thing on body of worms that is used in reproduction
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Superficial Annuli
ring...
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Cuticle
a nonliving external layer secreted by the epidermis
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collagen
a structural protein present throughout the Metazoa and abundant in vertebrate connective tissue
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Cryptobiosis
state of suspended animation, can stop when environment becomes too dry, they can be dormant then wake up fine later when the environment is fit
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Roundworm lifecycle
- penetrate human skin
- circulates til it gets to the intestines where it then lays its eggs
- babies hatch and it starts all over again
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Annelida
- 15,000 species
- metameric segmentation
- setae
- coelom
- hydrostatic skeleton
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Annelida
- Polychaeta- clamworms, plumed worms, scaleworms, lugworms, etc
- Oligochaeta- earthworms
- Hirudinea
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Annelida- Polychaeta
- 10,000 species, mostly marine
- parapodia
- setae
- head with sense organs
- very mobile
- sedentary forms
- suspension feeders
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Annelida- Oligochaeta
- terrestrial and freshwater- 3,000 species
- earthworms
- setae
- hermaphroditic
- no parapodia
- clitellum
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Annelida- Hirudinea
- most freshwater, 500 species
- lost setae
- superficial annuli
- hermaphroditic
- clitellum
- temporary or permanent ectoparasites
- suck blood with pharynx
- secrete numbing chemicals
- penetrate surface with proboscis
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Basal Ecdysozoans characteristics
- Nematodes have a non chitinous exoskeleton
- secrete cuticle
- composed of collagen protein
- secrete chitin in exoskeleton
- appendages for locomotion
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Onychophora- Velvet-worms
- about 70 species
- many pairs of unjointed legs
- chitin in exoskeleton
- rich in fossil records
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Nematoda- roundworms
- extremely numerous and diverse- 12,000 species
- free-living, symbiotic, and parasitic
- variety of habitats
- no legs
- longitudinal muscles only
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