A diagram of a hypothetical ancestral mollusc (HAM) with osphradia indicated on the far right side of the image inside the posterior mantle cavity
The osphradium is a pigmented chemosensory epithelium patch in the mantle cavity present in six of the eight extant classes of molluscs (it is absent in the scaphopoda and monoplacophora; among cephalopoda, only the nautilus has what appears to be a set of osphradia), on or adjacent to the ctenidia (gills). The main function of this organ is disputed but it is believed to be used to test incoming water for silt and possible food particles or, in some species, for sensing the presence of light.
It is a popular idea among malacologists that the presence of an osphradium should be a molluscan synapomorphy. However, an osphradium is absent in monoplacophorans and scaphopods.[1] Moreover, the differences in enervation of these patches suggest that the osphradium (as a patch enervated from the ctenidial nerve) may be different from another organ sometimes called the posterior sensory organ (PSO) with separate enervation from the lateral nerve cords. Both types of sensory organs are found in the nautilus.[2]
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Ponder, Winston F.; Lindberg, David R. (1997). "Towards a phylogeny of gastropod molluscs: An analysis using morphological characters". Zoological Journal of the Linnean Society. 119 (2): 83–265. doi:10.1111/j.1096-3642.1997.tb00137.x.
^David R. Lindberg; Julia D. Sigwart (2015). "What is the molluscan osphradium? A reconsideration of homology". Zoologischer Anzeiger. 256: 14–21. doi:10.1016/j.jcz.2015.04.001.
The osphradium is a pigmented chemosensory epithelium patch in the mantle cavity present in six of the eight extant classes of molluscs (it is absent in...
foot with sometimes a posterior mucous gland. Their olfactory organ, the osphradium is enlarged. In some species there are oesophageal pouches present. Their...
tongue, used as a rasping tool. unpaired osphradium (olfactory organ). lateral ciliated zones of osphradium a single left hypobranchial gland (on organ...
mechanoreceptors or chemoreceptors, in some cases located on short tentacles. The osphradium is a patch of sensory cells located below the posterior adductor muscle...
slow-moving, and use a venomous harpoon to disable faster-moving prey. The osphradium in cone snails is more specialized than in other groups of gastropods...
ganglion; g. ctenidium; l. auricle; m. mouth; n. nephridial opening; o. osphradium; pa. parietal ganglion; pe. pedal ganglion; pl. pleural ganglion; v. ventricle...
mass and a spiral movement of the body, the gill, the kidney and the osphradium (which means sensory receptor, or olfactory organ) have disappeared on...
of evolution. This means, among other things, that the limpet's left osphradium and oshradial ganglion (an organ believed used to sense the time to produce...
gastropods have lost the ctenidium (comb-like respiratory apparatus) and osphradium, and the pallial cavity has been modified as a lung. According to the...
base of the siphon is the bipectinate (branching from a central axis) osphradium, a sensory receptacle and olfactory organ, that is more developed than...
pedal ganglia had to conduct a twist— this means, for example, that the osphradium on the animal's left side is innervated through the right side of its...
ganglion; g. ctenidium; l. auricle; m. mouth; n. nephridial opening; o. osphradium; pa. parietal ganglion; pe. pedal ganglion; pl. pleural ganglion; v. ventricle...
snail slime sensory organs of gastropods caryophyllidia Hancock's organ osphradium rhinophore nervous system of gastropods euthyneury streptoneury torsion...
morphological changes : a thin basal plate, a very long snout and a small osphradium. They live in colonies with a few big females are surrounded by many smaller...
heart with two atria. They have retained only one kidney and the second osphradium has been lost in the course of evolution. The mantle cavity contains a...
This respiratory gill consists of 10 to 200 triangular filaments. The osphradium, the olfactory organ linked with the respiration organ, is usually relatively...
visceral mass, mainly consisting of the glands of the genital system. The osphradium is black at its base and has a peculiar form. The gill leaflets are not...
hermaphrodites. Due to their small size, they do not have a heart, an osphradium or a ctenidium. "Cima minima (Jeffreys, 1858)". www.gbif.org. Retrieved...
filaments, that are broadly triangular with lateral surfaces ridged. Osphradium is narrow, positioned slightly posterior to middle of ctenidium. Radula...
is used to suck water into the mantle cavity. There is a bipectinate osphradium located at base of siphon and branches off from a central axis. There...
glands are the same as those found in Arion species but the vestigial osphradium (kidney-like structure) within the mantle chamber is more distinct than...
across the roof of the pallial cavity. In its distal part, behind the osphradium, it shows two distinct flexures, coming back upon itself and, after a...
or other organisms is possibly mediated by sensory organs such as the osphradium. In the case of L. canarium, the perception of a predator can occur through...
and innervates the right body wall; no histologically differentiated osphradium could be detected. The buccal ganglia are positioned posterior to the...
25 to 28 filaments, shifted towards the right of apex. It also has an osphradium located near the middle of the gills and respiratory organs. It’s rectum...
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