Cirrchoanvalvia ("tentacle cone valve") is a class of kinespetrod distinguised by bilateral body symmetry, a prominent head, complex nervous systems, and muscular hydrostats in the form of arms or tentacles. The class has 30,000 species. The class is exclusively marine. The class has approximately 45,000 species.
They are free swimming and possess a head with two simple lensless eyes. They each have a smooth conical shell, with a large body chamber, divided into chambers that are filled with an inert gas, making the animal buoyant in the water. As many as 90 tentacles are arranged in two circles around their mouth. The animal has jaws which are horny and beak-like, and it is a predator. It is not usually found in waters less than 100 meters deep and may be found as far down as 500 to 700 meters (2,300 feet).
Cirrchoanvalves move primarily by jet propulsion or by using their arms for locomotion. Jet propulsion is achieved by taking oxygenated water into the mantle cavity to the gills and through muscular contraction of this cavity and expelling it through a fold in the mantle. Motion usually backward as water is forced out anteriorly.
The long conical cirrchoanvalve shell is marked by sealed internal chambers known as camerae. The thin walls between the camerae are called the septa. As cirrchoanvalves grow, they detach their body from the walls of the shell, moves forward, and secretes a new septum behind it. Each septum adds created a new camera in the shell. The body of the animal itself occupied the last chamber of the shell - the living chamber. The septa are perforated by a siphuncle, which runs through each of the internal chambers of the shell. Some species deposite calcium carbonate in the empty chambers (called cameral deposits) via the siphuncle to help control buoyancy. Sutures are visible as a series of narrow wavy lines on the surface of the shell where each septa contacts the wall of the outer shell.