Gastrodermis

Gastrodermis

The gastrodermis is a tissue layer found in cnidarians, such as jellyfish, corals, and sea anemones. It lines the gastrovascular cavity, which is the primary site of digestion and nutrient absorption in these organisms. The gastrodermis is derived from the endoderm during embryonic development and plays a crucial role in the physiology of cnidarians.

Cross-section of a jellyfish showing the gastrodermis (numbered).

Structure

The gastrodermis is composed of a single layer of cells that are specialized for various functions. These cells include:

• Nutritive-muscular cells: These cells are responsible for the digestion of food particles. They contain digestive enzymes and are capable of phagocytosis, engulfing food particles and breaking them down intracellularly.
• Gland cells: These cells secrete digestive enzymes into the gastrovascular cavity to aid in the extracellular digestion of food.
• Ciliated cells: These cells have cilia that help to circulate the contents of the gastrovascular cavity, ensuring that nutrients are evenly distributed and waste products are expelled.

Function

The primary function of the gastrodermis is to facilitate digestion and nutrient absorption. In cnidarians, digestion occurs in two stages:

1. Extracellular digestion: Digestive enzymes secreted by gland cells break down food particles in the gastrovascular cavity. 2. Intracellular digestion: Nutritive-muscular cells engulf the partially digested food particles and complete the digestion process within their vacuoles.

The gastrodermis also plays a role in gas exchange and the expulsion of waste products. The thin layer of cells allows for the diffusion of oxygen and carbon dioxide, as well as the removal of nitrogenous wastes.

Related pages

• Cnidaria
• Jellyfish
• Coral
• Sea anemone
• Gastrovascular cavity