Cnidario Cnidari Cnidarians Celenterati intotheblue.it
Body with normally radial symmetry; It has the shape of a bag whose inner cavity is called a gastric cavity. The gastric cavity opens on the outside in a mouth.
The Cnidaria can be solitary or colonial and certainly represent the most beautiful and imaginative forms among the marine invertebrates.
Within the Cnidaria there are two basic types of organization: Octopus, sedentary fixed to the substrate, and jellyfish freely floating.
What you see in the film and in the photos is in the form octopus attached to the cliff with the mouth apparatus facing upwards surrounded by numerous tentacles. We met him during a deep dive at about 82 meters deep.
The lower part fixed to the substrate allows the animal to move slowly on the bottom and find the best position that best allows the nutrition; The Cnidaria in fact are carnivores, they feed on small crustaceans of small fish.
The prey is captured thanks to the inoculation of poison through the cnidocisti, of which all the species of the phylum are provided and later introduced into the inner cavity to be digested. Digestion is in part extracellular and partially intracellular. Extracellular digestion occurs because of digestive enzymes produced in the gastrovascolare cavity. Intracellular digestion is obtained by the same cells that engulf and digest within small particles of food. The digestion residues are then expelled from the mouth into the external environment.