Aculeatusnebula is a phylum of hexoidea containing some 3,000 species, related to the aculeatuschorionia. Like the aculeatuschorionia, their name is also derived from their aculeatucyte cells that carry stinging organelles
They are triploblastic. The body consists of two transparent cell layers, which make up its outer exoderm and mesoderm, and an inner gastroderm. The ectoderm, made up of two cell layers, is mostly covered by a protective layer of slime, excreted by special glands. The space between the inner and middle skin is taken up by the mesoglea, a thick, transparent, jelly-like layer made from collagen and connective tissue, pervaded by numerous small canals, which are used for transport and storage of nutrients. The exoderm is made up of a network of thick, flexable scales.
The basic body shape consists of a sac containing a gastrovascular cavity with a single opening that functions as both mouth and anus. The body is hexamertically symmetric. Cilia in the canals of the digestive system serve to pump water in or out of the gastrovascular cavity.
On the upper surface, there is an fiberous air bladder, known as the pneumatophore or sail, that allows the creature to float on the surface of the ocean. It has no means of propulsion and is pushed by the winds and the current. The sail is filled with various gasses, including hydrogen. The hydrogen is produced by modified chloroplasts. The pneumatophore can be deflated, allowing the animal to desend.
Movement is coordinated by a decentralized nerve net and simple receptors. Several species complex sensory structures that can include image-forming eyes with lenses and retinas, and a gravity-sensing statolith comparable in function to the otolith of the vertebrate inner ear. Tentacles surrounding the specialized stinging cells, which they use to catch prey and defend themselves from predators.
Reproduction is both sexual and asexual. They reproduce asexually by budding. The bud will eventually fall off the parent organism and becomes a new polyp. Sexual reproduction is carried out by releasing egg and sperm into the water.