Flatworms and Roundworms

Bilateral symmetry

Body plan in which only a single, imaginary line can divide the body into two equal halves.

Pharynx

A muscular tube near the mouth that aids in feeding.

Flame cell

Specialized cells that remove excess water from the body.

Eye spot

Group of cells that can detect changes in the amount of light in the environment

Regeneration

Process where severed body parts can regrow.

Host

An organism that shelters and nourishes a parasite.

GVC

Digestive cavity with a single opening, in which cells secrete enzymes to break down food

Fluke

A parasitic flatworm of the class Trematoda.

Tape worm

A parasitic flatworm of the class Cestoda.

Scolex

The anterior end of a tapeworm, bearing suckers and hooks for attachment.

Proglottid

Each segment in the strobila of a tapeworm, containing a complete sexually mature reproductive system.

Planaria

A free-living flatworm of the class Turbellaria.

Parasite

An organism that lives in or on another organism (its host) and benefits by deriving nutrients at the host's expense.

Anus

The opening at the opposite end of the digestive system from the mouth, through which waste products are eliminated.

One-way digestion

A digestive system with two openings, a mouth for ingestion and an anus for excretion, allowing for continuous processing of food.

Cuticle

A tough, external layer that protects nematodes from desiccation and other environmental conditions.

Vinegar eel

Free-living nematodes that feed on the bacteria in vinegar.

Ascaris

A genus of parasitic nematode worms in the roundworm family Ascarididae.

Hookworms

Parasitic nematodes that infect the small intestine.

Trichinella's/Trichina

A genus of parasitic nematodes that cause trichinosis.

Trichinosis

A disease caused by the nematode Trichinella spiralis.

Pinworms

Nematodes that infect the intestines and colon of humans.

Filaria

Thread-like parasitic roundworms that belong to the superfamily Filarioidea.

Elephantiasis

A condition caused by parasitic worms.

Guinea worm

A parasitic nematode that causes the disease dracunculiasis.