Test 3-Platyhelminthes Flashcards
Helminth
worm
Environment or Habitat
parasitic or free-living (water: lakes, streams, damp soil)
Common representatives
planaria, flukes, tapeworms
Planaria
free living fresh water example: turbellaria eyespots gray, brown, black regenerate lost body parts
Flukes
parasitic short and flat male and female live anywhere digestive system
Tapeworms
long and flat
cestoda: from uncooked meat that is infected, also fecal contamination
live in intestines
no digestive systems
Symmetry
bilateral not segmented
Muscular system
use cilia to move
Skin
3 layers
gas is exchanged across skin
avoids white blood cell detection-so it can get into humans
Digestive system
primitive
1 opening
branch digestive system
excretion by special cells and canals
Other organ systems
no respiratory, circulatory, or skeletal systems
Size
some less than 1 mm
others are several meters long
Nervous system
nerve endings come together at the anterior or head to form what is almost a brain
Organs
simple sense organs
simple muscles
Parasitic Characteristics
have special suckers for holding onto host
special skin to help avoid detection by host
can be harmful to humans
Life Cycle
both sexes in one organism (both male and female parts)
tapeworm releases end body segments that are full of eggs; drop out of host body through feces
sometimes asexual reproduction by fission or splitting
Relative complexity
relatively simple, they have the beginnings to organ systems
Platy
flat
