Introduction to Phylum Platyhelminthes (Flatworms)

These flashcards cover the general characteristics, classes, structure, and systems of Phylum Platyhelminthes, including key vocabulary and definitions.

Dorsoventral flattening

A key characteristic of Platyhelminthes which refers to their flattened body shape.

Bilateral symmetry

A body plan in which the left and right sides are mirror images of each other.

Cephalization

The concentration of sensory receptors and nervous tissue at the anterior end of the organism.

Acoelomate

Organisms that lack a fluid-filled body cavity.

Gastrovascular cavity

A central cavity that serves both digestive and circulatory functions.

Triploblastic

Organisms that have three germ layers: ectoderm, mesoderm, and endoderm.

Organ level of organization

A level of biological organization where tissues combine to form organs.

Turbellaria

A class of flatworms that are generally free-living.

Monogenoidea

Parasitic class of flatworms known as flukes that are ectoparasites.

Trematoda

Parasitic class of flatworms known as flukes that are endoparasites.

Cestoda

Parasitic class of flatworms known as tapeworms that are endoparasites.

Tegument

The protective outer covering of flatworms, differing in structure between free-living and parasitic species.

Ciliated epithelium

A layer of cells with hair-like structures found in free-living flatworms for movement.

Syncytial adult tegument

A layer of flattened cells in adult parasitic flatworms that helps resist host defenses.

Osmoregulation

The process of maintaining water balance within the body.

Blind sac

The term used to describe the gastrovascular cavity which has only one opening.

Monecious

Organisms that possess both male and female reproductive organs.

Self fertilization

A reproductive method where an organism can fertilize its own eggs.