Editing Nemertea (section)

=== Proboscis and feeding ===

The [[proboscis]] is an infolding of the body wall, and sits in the rhynchocoel when inactive.<ref name="WalkerAnderson1998Nemertea" /> When muscles in the wall of the rhynchocoel compress the fluid inside, the pressure makes the proboscis jump inside-out along a canal called the rhynchodeum and through an orifice, the proboscis pore. The proboscis has a muscle which attaches to the back of the rhynchocoel, can stretch up to 30 times its inactive length and acts to retract the proboscis.<ref name="RFB2004FormBodyProboscis" />

[[File:Gorgonorhynchus repens.jpg|''[[Gorgonorhynchus repens]]'', a species within class Anopla, discharges a sticky branched proboscis.|245px|right|thumb]]The proboscis of the [[Class (biology)|class]] [[Anopla]] exits from an orifice which is separate from the mouth,<ref name="RFB2004FormBodyProboscis" /> coils around the prey and immobilizes it by sticky, toxic secretions.<ref name="RFB2004NutritionDigestive" /> The Anopla can attack as soon as the prey moves into the range of the proboscis.<ref name="McDermottRoe1985" /> Some Anopla have branched proboscises which can be described as "a mass of sticky spaghetti".<ref name="RFB2004FormBodyProboscis" /> The animal then draws its prey into its mouth.<ref name="WalkerAnderson1998Nemertea" />

[[File:Amphiporus ochraceus stylet region.jpg|Stylet-containing part of proboscis of "armed" nemertean ''Amphiporus ochraceus''.|245px|right|thumb]]
In most of the class [[Enopla]], the proboscis exits from a common orifice of the rhynchocoel and mouth. A typical member of this class has a [[Stylet (anatomy)|stylet]], a [[calcareous]] barb,<ref name="RFB2004FormBodyProboscis" /> with which the animal stabs the prey many times to inject toxins and digestive secretions. The prey is then swallowed whole or, after partial digestion, its tissues are sucked into the mouth.<ref name="RFB2004NutritionDigestive" /> The stylet is attached about one-third of the distance from the end of the [[wikt:eversion|evert]]ed proboscis, which extends only enough to expose the stylet. On either side of the active stylet are sacs containing back-up stylets to replace the active one as the animal grows or an active one is lost.<ref name="RFB2004FormBodyProboscis" /> Instead of one stylet, the [[Polystilifera]] have a pad that bears many tiny stylets, and these animals have separate orifices for the proboscis and mouth, unlike other Enopla.<ref name="RFB2004Diversity" /><ref>{{cite book|last1=Roe|first1=Pamela |last2=Norenburg|first2=Jon L. |last3=Maslakova|first3=Svetlana |editor=Sol Felty Light |editor2=James T. Carlton|title=The Light and Smith Manual: Intertidal Invertebrates from Central California to Oregon |url=https://books.google.com/books?id=64jgZ1CfmB8C&q=Polystilifera&pg=PA223|access-date=4 Feb 2011|year=2007|publisher=University of California Press|isbn=978-0-520-23939-5|pages=221–233}}</ref> The Enopla can only attack after contacting the prey.<ref name="McDermottRoe1985" />

Some nemerteans, such as ''L. longissimus'', absorb organic food in solution through their skins, which may make the long, slim bodies an advantage.<ref name="MooreOverhill2006" /> [[Suspension feeding]] is found only among the specialized symbiotic [[bdellonemertea]]ns,<ref name="McDermottRoe1985" /> which have a proboscis but no stylet, and use suckers to attach themselves to [[bivalve]]s.<ref name="Light1974">{{cite book|last=Light|first=Sol Felty|title=Intertidal Invertebrates of the Central California Coast|year=1974|publisher=University of California Press|isbn=978-0-520-00750-5|pages=55–58|chapter-url=https://books.google.com/books?id=2Qnod-98-q8C&q=bdellonemertea&pg=PA56|edition=2|access-date=22 February 2011|chapter=Phylum Nemertea (Rhynchocoela)}}</ref>