There is a network of tracheoles close beneath the general body cuticle ,but often there are leaf-like extensions of the body forming gills.These are covered by a very thin cuticle with cuticle with a network of tracheoles immediately beneath and they are known as tracheal gills.• There is a network of tracheoles close beneath the general body cuticle ,but often there are leaf-like extensions of the body forming gills.These are covered by a very thin cuticle with cuticle with a network of tracheoles immediately beneath and they are known as tracheal gills