Mesoglea

Mesoglea, also known as mesohyl, is a gelatinous substance that forms the middle layer of cnidarians and ctenophores, two major groups of aquatic invertebrates. This layer lies between the outer protective layer, the epidermis, and the inner layer, the gastrodermis, that lines the gut. Mesoglea plays a crucial role in the structure and function of these organisms, contributing to their buoyancy, shape, and movement.

Composition and Structure

Mesoglea is primarily composed of water, making up 95% or more of its volume, which contributes to its jelly-like consistency. The remaining components are a mix of collagen and other fibrous proteins, glycoproteins, and a variety of cells. These cells can include fibroblast-like cells that produce the fibrous proteins, as well as immune cells that help defend the organism from pathogens. Unlike the epidermis and gastrodermis, which are layers of tightly packed cells, the mesoglea is not cellular but rather a complex matrix of materials that provide structural support.

Function

The mesoglea serves several important functions in cnidarians and ctenophores:

• Buoyancy: Its high water content allows these animals to be buoyant in the water column, enabling them to float and move with minimal energy expenditure.
• Shape and Support: The mesoglea provides structural support, maintaining the shape of the organism. In some species, it can be quite thick, contributing significantly to their overall size.
• Locomotion: For some cnidarians, like jellyfish, the mesoglea plays a role in locomotion. The contraction of muscles embedded in the mesoglea, along with the elastic recoil of this layer, helps propel the jellyfish through the water.
• Shock Absorber: The gelatinous nature of the mesoglea helps protect the internal organs from mechanical damage.

Evolutionary Significance

The mesoglea represents an evolutionary solution to the challenges of life in an aquatic environment, providing buoyancy and structural support without a heavy skeletal framework. Its simplicity and effectiveness highlight the evolutionary success of cnidarians and ctenophores, which have existed for millions of years.

Research and Applications

Research into the composition and properties of mesoglea has potential applications in biomaterials science, particularly in the development of hydrogels that mimic its properties. These hydrogels could have applications in medicine, such as in drug delivery systems or as scaffolds for tissue engineering.

See Also

• Cnidaria
• Ctenophora
• Hydrogel
• Tissue engineering