Flatworms, belonging to the phylum Platyhelminthes, are a group of soft-bodied, usually flattened invertebrates that exhibit bilateral symmetry and lack a body cavity, making them acoelomates. They are known for their simple body structure, which includes a gastrovascular cavity with a single opening, and many species are parasitic, affecting both humans and animals.

Flatworms

Phylum Platyhelminthes

Soft-bodied invertebrates

Bilateral symmetry is a form of symmetry in which an organism or object can be divided into two identical halves along a single plane, typically associated with the evolutionary development of a head and tail. This type of symmetry is prevalent in the animal kingdom and is crucial for directional movement and sensory organ placement.

Bilateral Symmetry

A body cavity is a fluid-filled space within the body that houses and protects internal organs, facilitating their movement and function. These cavities are categorized into dorsal and ventral, with the ventral cavity further divided into thoracic and abdominopelvic regions, each serving distinct physiological roles.

Body Cavity

Acoelomates

Simple body structure

The gastrovascular cavity is a central digestive compartment with a single opening, serving both ingestion and excretion in certain simple animals. It facilitates the distribution of nutrients throughout the organism, as it lacks a separate circulatory system.

Concepts

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