{{Short description|An organ in the mouthparts of animals}} [[File:Palpus.png|thumb|Schematic representation of palps (in red) in:<br /> A. ''Anopheles'', B. Orthoptera, C. a flea]] A '''palp''' (also called '''palpus''', from latin ''palpare'' "to pat, touch") is an organ in the mouthparts of various animals. For example, palps are found in various annelids, insects, arachnids and crustaceans.{{Efn|From a phylogenetic standpoint, insects are a group of crustaceans. See Pancrustacea for further details.}} They are always arranged in pairs.
The term "palp" can be misleading, as many animals use them for more than only as an organ of touch. Often palps have bristles packed densely, wich are not only used for touch, but also for chemoreception.
==Arthropods== [[File:Paranchus albipes detail1.jpg|thumb|left|Head of a beetle (''Paranchus albipes'') seen from below, partially coloured on the right.<br />''Red:'' antennae<br /> ''Blue-green:'' maxillary palp<br />''Green:'' labial palp<br />''Pink:'' pair of bristles on the second to last segment of the labial palp]] In some groups, such as beetles and lepidopterans, labial and maxillary palps (''palpus labialis'' and ''maxillaris'', respectively) can be distinguished. The formers are attached to the labium, while the latter to the maxillae.
Pedipalps are multifunctional organs of arachnids. They can be used for communication (stridulation, substrate or web percussion, optical signals), but also courtship display, mating (in spiders) or movement (palpigrades). Pedipalps can be modified into pincers or as bite and digging instruments (mites). In this last group, palps have a simple, linear form, made of four segments, while other arachnids mostly have palps made up of five segments.<ref>{{Cite journal|last1=Lindquist|first1=E.|last2=Sidorchuk|first2=E.|title=The labidostommatid palpus: a morphological enigma (Acariformes: Prostigmata)|journal=Acarologia|volume=55|issue=3|date=2015|pages=337–350|doi=10.1051/acarologia/20152172}}.</ref>
For insects and spiders form, placement, and inner construction of the palps, as well as their presence or lack thereof are used as determination characteristics.<ref>{{Cite journal|last=Merrett|first=P.|title=The palpus of male spiders of the family Linyphidae|journal=Proceedings of the Zoological Society of London|volume=140|issue=3|date=1963|pages=347–467|doi=10.1111/j.1469-7998.1963.tb01867.x}}</ref><ref>{{Cite journal|last=Coddington|first=Jonathan A.|title=Ontogeny and Homology in the Male Palpus of Orb-weaving Spiders and Their Relatives, with Comments on Phylogeny (Araneoclada: Araneoidea, Deinopoidea)|journal=Smithsonian Contributions to Zoology|volume=496|date=1990|issue=496 |pages=1–52|doi=10.5479/si.00810282.496 |bibcode=1990SCZoo.496....1C |url=https://repository.si.edu/bitstream/handle/10088/5479/SCtZ-0496-Hi_res.pdf?sequence=1&isAllowed=y}}</ref><ref>{{Cite journal|last1=Zhang|first1=Ru|last2=Zhang|first2=Zhong-jie|last3=Yu|first3=Ye|last4=Huang|first4=Yong-ping|last5=Qian|first5=Ai-rong|last6=Tan|first6=An-jiang|title=Proboscipedia and Sex combs reduced are essential for embryonic labial palpus specification in Bombyx mori|journal=Journal of Integrative Agriculture|volume=19|issue=6|date=2020|pages=1482–1491|doi=10.1016/S2095-3119(19)62785-1 |bibcode=2020JIAgr..19.1482Z |doi-access=free}}</ref><ref>{{Cite journal|last=Morimoto|first=Hiroyuki|title=The use of the labial palpus as a measure of proboscis length in worker honeybees Apis mellifera ligustica and Apis cerana cerana|journal=Journal of Apicultural Research|volume=7|issue=3|date=1968|pages=147–150|doi=10.1080/00218839.1968.11100205 |bibcode=1968JApiR...7..147M }}</ref>
==Annelids== [[File:Magelona johnstoni.jpg|thumb|The magelonid ''Magelona johnstoni'', down on the left both long palps are shown]] In annelids palps can be used for nutrition or as sense organs; normally the former are long and filiform, while the latter are stud. Those that are used for nutrition can have a ciliated groove, through which nourishment is transported. It is assumed that the last common ancestor of all annelids had palps (it is a plesiomorphic character of annelids).<ref name="Kalke">{{cite journal|last1=Kalke|first1=Paul|last2=Linder|first2=Samira S.|last3=Beckers|first3=Patrick|date=2024-01-04|title=Palps across the tree - the neuronal innervation and development of sensory head appendages in Annelida|journal=Frontiers in Neuroscience|volume=17|article-number=1310225|doi=10.3389/fnins.2023.1310225|doi-access=free |pmid=38239828 |pmc=10794354 }}</ref><ref name="Ballentine">{{cite journal|last1=Ballentine|first1=Will|last2=Dorgan|first2=Kelly M.|date=2023|title=Locomotory Palp Function in Interstitial Annelids|journal=Biological Bulletin|volume=244|issue=1|pages=51–62|doi=10.1086/724580|pmid=37167622 |url=https://www.researchgate.net/publication/369273293|access-date=2026-04-08}}</ref>
Palps are present in Magelonidae and Oweniidae (these families constitute Palaeoannelida), just as in Chaetopterida, in Errantia (in the families Protodrilidae, Saccocirridae and Dorviellidae) and in Sedentaria (in the families Sabellariidae, Siboglinidae, Terebellidae, Spionidae and Cirratuliformia). In the family Amphinomidae there are five similar sense organs: a central antenna, a pair of lateral antennae and a further pair of sense organs, sometimes called "antennae" and sometimes "palps". The larva of the Amhinomidae (Rostraria larva) has a pair of palps for nourishment.<ref name="Kalke" /><ref name="Ballentine" />
==Molluscs== [[File:Anatomie de pecten.jpg|thumb|left|Anatomy of a scallop, in the top right a labial palp (''palpe labial'') is shown]] Bivalves, with the exeption of Protobranchia, have three structures with which they filter the water: the gills, the lipps and the labial palp. The labial palps in scallops are two pairs of lobes on the mouth margin, they can have cilia and cells that produce mucus (mucocites).<ref>{{cite journal|last1=Beninger|first1=P. G.|last2=Auffret|first2=M.|last3=Le Pennec|first3=M.|date=1990-06-01|title=Peribuccal organs of Placopecten magellanicus and Chlamys varia (Mollusca: Bivalvia): Structure, ultrastructure and implications for feeding|journal=Marine Biology|volume=107|issue=2|pages=215–223|language=en|access-date=2026-04-08|doi=10.1007/BF01319820|url=https://link.springer.com/article/10.1007/BF01319820|url-access=subscription}}</ref>
In some carnivorous gastropods lateral labial palps are present, that help the animals find food.<ref>{{cite web|language=en|url=https://www.britannica.com/animal/gastropod/The-shell#ref413143|title=Gastropod: the head|publisher=Britannica|access-date=2026-04-10}}</ref>
==References== {{notelist}}
<references/>
Category:Protostome anatomy