Tentacles are a common feature in aquatic and semi-aquatic animals. In zoology, a Tentacles is a small retractable, movable organ found in almost all species of aquatic animals, many of them invertebrates. In animal physiology, tentacles generally occur in a single or multiple pairs, depending upon their size and shape. In fish, they are present on the head, under tail, external skin folds and in the genital area.
In the field of anatomy, tentacles are part of the phalloplankton. Phalloplankton is an organism that requires an external factor to cause its movement. This external factor is called a pump. The most commonly used pumps in phalloplankton are siphonophores, which can be present at the base of the tentacles and along the boundary of the oral cavity, feeding on the contents of the stomach. In the case of bluefish and other members of the bony fish family, siphonophores are present at the bottom of the water.
Tentacles are generally used to sense movement or position and they help filter food particles. siphonophores also produce a gaseous secretion, which is injected into the water column through the mouth. The gaseous secretion acts as a sensor to detect the presence of other organisms such as bacteria and other parasites. The presence of other organisms triggers the secretion of a particular kind of fluid known as an exosome, which is released into the uppermost parts of the water column where it gets picked up by the gills and transported towards the photoreceptor cell of the Tentacles.
Tentacles can be used to filter air. This is because they contain spongy tissue, which can trap microorganisms and filter out gas and other molecules that are dissolved in water. The tentacles are capable of filtering up to 100 gallons of water, depending on their length. Tentacles are also used in the process of removing oxygen from the water. Since oxygen molecules are negatively charged, the tentacles accumulate negative ions while pumping water, which neutralizes the positively charged ions present.
Squid tentacles have evolved into powerful and flexible filtering tentacles. They have excellent muscular strength and are covered with small bristles that protect them from cuts. Small ridges along the tentacle edge help the squid to maneuver. Squid's large size allows them to remain motionless for long periods of time. Squid's siphonophores have strong cords which enable them to trap air or allow them to move in an upright position. The cord is also short enough not to obstruct the flow of air into the squid's food sack.
The tentacles are used in the digestive process of phalloplankton. Phalloplankton is the major source of oxygen in seawater. As the phalloplankton moves through water, it creates a gaseous exhalation. The gaseous exhalation passes through the tentacles and gets attached to the undersides of the fish's head. This process of gaseous exhalation, called bloating, is essential to the health and growth of the fish.