Editing Tentacle (section)

=== Molluscs ===
{{See also|Cephalopod limb}}
[[Image:Snail-front-0A.jpg|thumb|right|Front view of land snail showing upper and lower sets of tentacles]]
[[Image:White abalone Haliotis sorenseni.jpg|thumb|350 px|Abalone showing pallial tentacles]]
Many molluscs have tentacles of one form or another. The most familiar are those of the [[Pulmonata|pulmonate land snails]], which usually have two sets of tentacles on the head: when extended the upper pair have eyes at their tips; the lower pair are [[chemoreceptor]]s. Both pairs are fully retractable [[muscular hydrostat]]s, but they are not used for manipulation or prey capture. Molluscs have one pair of tentacles close to their mouths that hold close to their captured prey before they can consume it.<ref name="FiCaDB">{{cite journal |last1=Kier |first1=William M. |date=February 2016 |title=The Musculature of Coleoid Cephalopod Arms and Tentacles |journal=Frontiers in Cell and Developmental Biology |volume=4 |page=10 |doi=10.3389/fcell.2016.00010|doi-access=free |pmid=26925401 |pmc=4757648 }}</ref>

Some marine snails such as [[abalone]] and top snails, [[Trochidae]], have numerous small tentacles around the edge of the [[mantle (mollusc)|mantle]]. These are known as ''pallial tentacles''.<ref name=bou/>

Among [[cephalopod]]s, squid have spectacular tentacles. They take the form of highly mobile muscular hydrostats with various appendages such as suction disks and sometimes thorny hooks. Up to the early twentieth century "tentacles" were interchangeably called "arms".<ref name= "CNH3">{{cite book |last1=Cooke |first1= A. H.  |last2=Shipley |first2=Arthur Everett  |date=1895 |title=The Cambridge Natural History |volume=34: Molluscs, Trilobites, Brachiopods etc. |location=London, England, U.K. |publisher= Macmillan Company}}{{page needed|date=October 2023}}</ref> These tentacles are made of stalks of axial [[ventral nerve cord|nerve cord]]s that are covered by circular transverse muscle tissue that contract in response to stimuli. There is a layer of helical muscle that helps each tentacle to twist or turn in any direction where the prey is sensed.<ref name="FiCaDB"/>

The modern convention, however, is to speak of appendages as "tentacles" when they have relatively thin "[[peduncle (anatomy)|peduncles]]" or "stalks" with "clubs" at their tips. In contrast the convention refers to the relatively shorter appendages as "arms". By this definition the eight appendages of octopuses, though quite long, count as arms.<ref name=bou>{{cite web |author= Boumis R |title= Animals With Tentacles |url= http://animals.pawnation.com/animals-tentacles-2495.html |year= 2013 |work= Pawnation |publisher= AOL Inc. |access-date= 2013-06-08 |url-status= live |archive-url= https://web.archive.org/web/20131203020936/http://animals.pawnation.com/animals-tentacles-2495.html |archive-date= 3 December 2013 |df= dmy-all }}</ref> While arms are distinct from tentacles (a definition specific to the limb featuring peduncles), arms do fall within the general definition of "tentacle" as "a flexible, mobile, and elongated organ" and "tentacle" could be used as an [[umbrella term]].

The tentacles of the [[giant squid]] and [[colossal squid]] have powerful suckers and pointed teeth at the ends. The teeth of the giant squid resemble [[crown cork|bottle caps]] and function like tiny [[hole saw]]s, while the tentacles of the colossal squid wield two long rows of swiveling, tri-pointed hooks.