How do flies drink?

Flies have a fascinating mechanism for drinking liquids, which differs significantly from the way humans and many other animals drink. Here's how flies drink:

Proboscis: Flies have a specialized mouthpart called a proboscis, which is a highly modified and elongated structure. The proboscis is designed for intricate feeding and drinking behaviors. It consists of several segments and is highly flexible, allowing the fly to reach different surfaces and angles for feeding purposes.

Labellum: At the tip of the proboscis is a small, fleshy, and spongy structure called the labellum. The labellum is covered with tiny taste hairs and tiny ducts called food canals. These food canals help transport the liquid food into the fly's digestive system.

Food Absorption: When a fly wants to drink, it extends its proboscis and places the labellum onto the liquid surface. The fly then uses its tongue-like structure to spread and absorb the liquid. The labellum is designed in a way that maximizes the surface area in contact with the liquid, allowing for efficient absorption.

Capillary Action: Flies primarily rely on capillary action for the ingestion of liquid food. Capillary action is the ability of a liquid to rise in a narrow tube against the force of gravity. The narrow food canals present in the labellum act like tiny capillaries. The liquid food rises through these canals due to cohesive and adhesive forces, enabling the fly to ingest it without actively sucking the liquid.

Filter Mechanism: In addition to capillary action, flies also use a filtering mechanism to separate liquid food from solid particles. The labellum contains small hairs or setae that act as filters, preventing the ingestion of unwanted solid particles.

Storage and Mixing: Flies have specialized structures called the cibarium and pharynx, which serve as storage and mixing chambers. The ingested liquid food is temporarily stored in the cibarium before passing through the pharynx. During this process, the fly may mix the food with enzymes or other digestive secretions for initial processing before further digestion occurs in the fly's gut.

It's important to note that different fly species may have slight variations in their feeding and drinking mechanisms, but the overall process of using the proboscis, labellum, capillary action, and filtration remains similar across various fly species.