biology 27 1 flatworms
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27-1 Flatworms
Acoelomate
• Animal lacking a coelom, or body cavity
Coelom
• Fluid-filled body cavity lined with mesoderm
Pharynx
• Muscular tube at the end of the gastrovascular cavity, or throat, that connects the mouth with the rest of the digestive tract and serves as a passageway for air and food.
Flame Cell
• Specialized cell that filters and removes excess water from the body of a flatworm.
Ganglion
• Group of nerve cells
Eyespot
• Group of cells that can detect changes in the amount of light in the environment.
Hermaphrodite
• Individual that has both male and female reproductive organs
Fission
• Form of asexual reproduction in which an organism splits into two, and each half grows new parts to become a complete organism.
Scolex
• Head of an adult tapeworm; can contain suckers or hooks.
Proglottid
• One of the segments that make up most of a tapeworm’s body.
testis
• Male reproductive organ that produces sperm.
Key Concept
• Flatworms are soft, flattened worms that have tissues and internal organ systems. They are the simplest animals to have three embryonic germ layers, bilateral symmetry, and cephalization
Key Concept
• Turbellarians are free-living flatworms. Most live in marine or fresh water.
Key concept
• Flukes are parasitic flatworms. Most flukes infect the internal organs of their host.
Key Concept
• Tapeworms are long, flat, parasitic worms that are adapted to life inside the intestines of their hosts.