presentations today: derek/travis nick/dustin rachel/arianne erica/jordan david/dalton colton/taylor...
Post on 03-Jan-2016
223 Views
Preview:
TRANSCRIPT
Presentations today:
Derek/TravisNick/Dustin
Rachel/ArianneErica/JordanDavid/DaltonColton/TaylorKatie/Dylan
Dewayne/Ciera
Nematoda (Roundworms) • widely distributed
• living in soil, animals,
• fresh and marine water
• Most are free-living
• many are parasitic.
Roundworm
• tapered at both ends
• no segments
• thick outer covering = Cuticle
• protects them in harsh environments
– Stomach acid
• Covering is shed 4 times as they grow.
Round bodyshape
Nematoda (Roundworms)
Tapered ends
• no circular muscles
• lengthwise (longitudinal) muscles
• one muscle contracts
• another muscle extends
• causes them to move in a thrashing motion from side to side
Nematoda (Roundworms)
• Have a pseudocoelom
• simplest animals with a one way digestive tract – mouth to anus
MouthIntestine Anus
Round bodyshape
Nematoda (Roundworms)
• Eyespots very reduced in parasitic roundworms.
Nematoda (Roundworms)
• Approximately half of species are parasites
• about 50 species infect humans.
Examples:
Ascaris, Pinworms, Trichenella, and Hookworms
• the most common roundworm infection in humans
Ascaris
• children infected more often than adults
– Why?
• Eggs in soil
– enter through the mouth of humans
Life Cycle--– hatch in intestines
– move into bloodstream
– eventually to lungs
– coughed up
– swallowed
– begin the cycle again.
• most common human roundworm parasites in U.S.
• highly contagious
• eggs can survive for up to two weeks on surfaces
Pinworms
• live eggs ingested
• mature in host’s intestinal tract
• female pinworms exit host’s anus – itching!
• lay eggs on nearby skin
• eggs fall onto bedding or other surfaces
• Reintroduced to intestine by mouth
• Trichinella causes a disease called “trichinosis”
• Found in raw or undercooked meat
• Can be sexually transmitted
Trichinella
Trichinella
• common in humans in warm climates
• Obtained when walking barefoot on contaminated soil
• Hookworms cause people to feel weak and tired due to blood loss.
Hookworms
• Nematodes can infect and kill pine trees, cereal crops, and food plants such as potatoes.
• They are particularly attracted to plant roots and cause a slow decline of the plant.
Roundworm Parasites
• They also can infect fungi and can form symbiotic associations with bacteria that help plants obtain nitrogen from air
• Nematodes also can be used to control pests
• Life on Earth is very dependent on nematodes
• Billions of nematodes in every one - symbiosis
top related