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The mantle cavity is a central feature of molluscan biology. This cavity is formed by the mantle skirt, a double fold of mantle which encloses a water space. This space contains the mollusk's gills, anus, osphradium, nephridiopores, and gonopores. The mantle cavity functions as a respiratory chamber in most mollusks. In bivalves it is usually ...
They are arranged into concentric circles on the bloated mantle, confusing predators as to the location of the eyes. If the threat still does not go away, its last resort is to again eject ink. However, the ink is not released, instead it is retained inside the now spherical mantle cavity. The squid thus becomes a completely opaque black ball. [34]
The dorsal part of the body wall is a mantle (or pallium) which secretes calcareous spicules, plates or shells. It overlaps the body with enough spare room to form a mantle cavity. The anus and genitals open into the mantle cavity. There are paired nerve cords. [18] Other characteristics that commonly appear in textbooks have significant ...
The siphon is part of the mantle of the mollusc, and the water flow is directed to (or from) the mantle cavity. A single siphon occurs in some gastropods. In those bivalves which have siphons, the siphons are paired. In cephalopods, there is a single siphon or funnel which is known as a hyponome.
A live individual of Pleurobranchaea meckelii; the ctenidium is visible as a feather-like structure in this view of the right-hand side of the animal. A ctenidium is a respiratory organ or gill which is found in many molluscs.
Within the mantle cavity there are three visceral photophores, an oval, anal photophore, a posterior intestinal photophore and an elongated posterior visceral photophore which forms a strip. [4] It has a broad head which is at least as wide as the mantle and there is an elongated photophore patch on the ventral surface of both eyes. [ 3 ]
When the mantle contracts, water is forced through the gills, which lie between the mantle cavity and the funnel. The water's expulsion through the funnel can be used to power jet propulsion. If respiration is used concurrently with jet propulsion, large losses in speed or oxygen generation can be expected. [62] [63] The gills, which are much ...
Giant squid have small fins at the rear of their mantles used for locomotion. Like other cephalopods, they are propelled by jet—by pulling water into the mantle cavity, and pushing it through the siphon, in gentle, rhythmic pulses. They can also move quickly by expanding the cavity to fill it with water, then contracting muscles to jet water ...