Stenorhynchus seticornis

Stenorhynchus seticornis was first described by Johann Friedrich Wilhelm Herbst in 1788, under the name Cancer seticornis. It was also described as "Cancer sagittarius" by Johan Christian Fabricius in 1793, a name which is now a junior synonym of S. seticornis.{{cite journal |author=Peter K. L. Ng |author2=Danièle Guinot |author3=Peter J. F. Davie |name-list-style=amp |year=2008 |title=Systema Brachyurorum: Part I. An annotated checklist of extant Brachyuran crabs of the world |url=http://rmbr.nus.edu.sg/rbz/biblio/s17/s17rbz.pdf |journal=Raffles Bulletin of Zoology |volume=17 |pages=1–286}} Pierre André Latreille erected the genus Stenorhynchus (originally mis-spelt Stenorynchus) in 1818, and S. seticornis was confirmed as the type species by the International Commission on Zoological Nomenclature in 1966.{{cite journal |year=1966 |title=Opinion 763. Stenorhynchus Lamarck, 1818 (Crustacea, Decapoda): validated under the plenary powers with designation of Cancer seticornis Herbst, 1788, as type-species |url=http://biostor.org/reference/1923 |journal=Bulletin of Zoological Nomenclature |volume=23 |issue=1 |pages=19–21}}

File:Cangrejo araña (Stenorhynchus seticornis), franja marina Teno-Rasca, Tenerife, España, 2022-01-05, DD 95.jpg]]

The body of S. seticornis is triangular, and the rostrum is drawn out into a long point with serrate edges.{{cite book |author=Gilbert L. Voss |year=2002 |title=Seashore Life of Florida and the Caribbean |publisher=Courier Dover Publications |isbn=978-0-486-42068-4 |chapter-url=https://books.google.com/books?id=scXKvA97b24C&pg=PA116 |chapter=Family Majidae. The Spider Crabs |pages=[https://archive.org/details/seashorelifeoffl00gilb/page/116 116–119] |url-access=registration |url=https://archive.org/details/seashorelifeoffl00gilb/page/116 }} The legs are also long and thin, up to {{convert|10|cm|abbr=on}} across,{{cite book |author=George Lewbel |author2=George S. Lewbel |author3=Larry R. Martin |name-list-style=amp |year=1991 |title=Diving Bonaire |publisher=Aqua Quest Publications |isbn=978-0-9623389-4-6 |chapter=Crustaceans |pages=105–108 |chapter-url=https://books.google.com/books?id=OXc8BlfvEbsC&pg=PA106}} and the animal's carapace may be up to {{convert|6|cm|abbr=on}} long.{{cite book |author=Eugene H. Kaplan |author2=Roger Tory Peterson |name-list-style=amp |year=1999 |title=A Field Guide to Coral Reefs: Caribbean and Florida |series=Volume 27 of Peterson Field Guides |publisher=Houghton Mifflin Harcourt |isbn=978-0-618-00211-5 |url=https://books.google.com/books?id=OLYPWMoBkccC&pg=PA163}} Colouration is variable in this species; the body may be golden, yellow or cream, marked with brown, black or iridescent-blue lines; the legs are reddish or yellow, and the claws are blue or violet. This species presents as diagnostic features: triangular body with long pointed snout (rostrum), carapace decorated with fine dark lines and claws often have violet tips. S. seticornis is most commonly associated with anemones, in groups ranging from one to six individuals in south-eastern Brazil.{{Cite journal|last1=Medeiros|first1=Diego V.|last2=de Anchieta C.C. Nunes|first2=José|last3=Reis-Filho|first3=José Amorim|last4=Sampaio|first4=Cláudio L.S.|date=2011-09-30|title=Yellowline arrow crab Stenorhynchus seticornis (Brachyura: Majidae) acting as a cleaner of reef fish, eastern Brazil|journal=Marine Biodiversity Records|volume=4|doi=10.1017/s1755267211000637|bibcode=2011MBdR....4E..68M |issn=1755-2672}}

Stenorhynchus seticornis is commonly found in the shallow sub-tidal on rock bottoms, corals, calcareous algae, and also on soft sediments, such as shelly gravel and sand. Its geographical distribution is restricted to the Occidental Atlantic, from North Carolina to Argentina.{{Cite journal|last1=Okamori|first1=Claudia Melissa|last2=Cobo|first2=Valter José|date=2003-09-19|title=Fecundity of the arrow crab Stenorhynchus seticornis in the southern Brazilian coast|journal=Journal of the Marine Biological Association of the United Kingdom|volume=83|issue=5|pages=979–980|doi=10.1017/s0025315403008178h|bibcode=2003JMBUK..83..979O |s2cid=86505995 |issn=0025-3154}} Stenorhynchus seticornis is found in the western Atlantic Ocean, from North Carolina and Bermuda to Brazil, including throughout the Caribbean Sea,. It lives on coral reefs at depths of {{convert|10|-|30|ft}}.{{cite web |url=http://animaldiversity.ummz.umich.edu/site/accounts/information/Stenorhynchus_seticornis.html |title=Stenorhynchus seticornis, yellowline arrow crab |work=Animal Diversity Web |publisher=University of Michigan |author=Melissa Block |year=2001 |accessdate=October 6, 2010}}

S. seticornis is nocturnal and territorial.{{cite web |url=http://whozoo.org/Intro2002/EmilioBarela/EB_ArrowCrab.html |title=Arrow crab |author=Emilio Barela |accessdate=October 6, 2010 |publisher=WhoZoo.org}} The species has displayed notable negative phototaxis, meaning the organism prefers to avoid sunlight,{{Citation |last=Schriever |first=Gerd |title=In Situ Observations on the Behaviour and Biology of the Tropical Spider Crab Stenorhynchus Seticornis Herbst (Crustacea, Decapoda, Brachyura) |date=1978 |work=Physiology and Behaviour of Marine Organisms |pages=297–302 |publisher=Elsevier |doi=10.1016/b978-0-08-021548-8.50041-3 |isbn=978-0-08-021548-8}} and changes location during the day and nighttime. It eats small feather duster worms and other coral reef invertebrates. This crab is commonly kept in reef aquariums to control bristle worm populations.{{cite web|url=http://www.aquariumslife.com/crabs/arrow-crab-stenorhynchus-seticornis/|archive-url=https://archive.today/20130117025355/http://www.aquariumslife.com/crabs/arrow-crab-stenorhynchus-seticornis/|url-status=usurped|archive-date=January 17, 2013|title=Arrow crab|accessdate=February 8, 2011|publisher=aquariumslife.com}}

S. seticornis is one of a number of different invertebrates that are found living in association with the sea anemone, Lebrunia danae. It is often found among the anemone's pseudotentacles along with Pederson's cleaning shrimp (Ancylomenes pedersoni) and the spotted cleaner shrimp (Periclimenes yucatanicus).{{cite journal |author1=William Herrnkind |author2=Gregg Stanton |author3=Edwin Conklin |name-list-style=amp |year=1976 |title=Initial characterization of the commensal complex associated with the anemone, Lebrunia danae, at Grand Bahama |journal=Bulletin of Marine Science |volume=26 |issue=1 |pages=65–71 |url=http://www.ingentaconnect.com/content/umrsmas/bullmar/1976/00000026/00000001/art00009}} The species is also notable for its propensity to decorate its body by attaching materials as camouflage, or if the attached organisms are noxious, to ward off predators through aposematism.{{cite journal |author=Bateson, William |author-link=William Bateson |year=1889 |title=Notes on the Senses and Habits of some Crustacea |journal=Journal of the Marine Biological Association of the United Kingdom |series=new series |volume=1 |pages=211–214 |doi=10.1017/S0025315400058045 |s2cid=250948106}}{{cite book |author1=Hultgren, Kristin |url=http://www-eve.ucdavis.edu/stachowicz/papers/Hultgren_Stachowicz_2011_BookChapter.pdf |title=Animal Camouflage |author2=Stachowicz, Jay |publisher=Cambridge University Press |year=2011 |isbn=978-0-521-19911-7 |editor1=Stevens, Martin |editor1-link=Martin Stevens (biologist) |chapter=Camouflage in decorator crabs: integrating ecological, behavioural and evolutionary approaches |format=PDF proofs |access-date=2012-12-13 |editor2=Merilaita, Sami |archive-url=https://web.archive.org/web/20170815183654/http://www-eve.ucdavis.edu/stachowicz/papers/Hultgren_Stachowicz_2011_BookChapter.pdf |archive-date=2017-08-15 |url-status=dead}} There have been a considerable number of reports regarding cleaning symbiosis among reef fish, moray eels, and squirrelfish. This is a somewhat unexpected relationship as moray eels and squirrelfish can be considered dangerous clients, because crabs are important elements of their diets. This behavior has only been observed in the natural environment in Brazilian waters but it is believed that this behavior also exists throughout its distribution.

During mating, the male places a spermatophore on the female, which she uses to fertilise her eggs. These fertilised eggs are then carried on the female's pleopods until they are ready to hatch into zoea larvae. These swim towards the ocean surface and feed on plankton. They grow through a series of moults, and eventually metamorphose into the adult form. When mature, the spermatozoa of S. seticornis show five lateral arms, similar to the sperm morphology of Inachus phalangium.{{Cite journal|last1=Antunes|first1=Mariana|last2=Zara|first2=Fernando J.|last3=López Greco|first3=Laura S.|last4=Negreiros-Fransozo|first4=Maria L.|date=June 2018|title=Male reproductive system of the arrow crabStenorhynchus seticornis(Inachoididae)|journal=Invertebrate Biology|volume=137|issue=2|pages=171–184|doi=10.1111/ivb.12214|bibcode=2018InvBi.137..171A |hdl=11336/96288 |s2cid=90675584 |issn=1077-8306|hdl-access=free}}

Climate majorly regulates the breeding period of the arrow crab. Seasonal variation of water temperature and sunlight duration are considered as the most important variables determining the breeding period of arrow crabs.{{Cite journal|last=Cobo|first=Valter José|date=2002-11-21|title=Breeding period of the arrow crab Stenorhynchus seticornis from Couves Island, south-eastern Brazilian coast|journal=Journal of the Marine Biological Association of the United Kingdom|volume=82|issue=6|pages=1031–1032|doi=10.1017/s0025315402006598|bibcode=2002JMBUK..82.1031C |s2cid=84753432 |issn=0025-3154}}

There is a positive relationship between fecundity and the size of the parental female. In fact, the size of the female is the key variable in determining the number of eggs per batch. The female also determines the reproductive output of arrow crabs.{{Cite journal|last1=Antunes|first1=Mariana|last2=Zara|first2=Fernando José|last3=López-Greco|first3=Laura S.|last4=Negreiros-Fransozo|first4=Maria Lucia|date=2016-04-08|title=Morphological analysis of the female reproductive system ofStenorhynchus seticornis(Brachyura: Inachoididae) and comparisons with other Majoidea|journal=Invertebrate Biology|volume=135|issue=2|pages=75–86|doi=10.1111/ivb.12118|bibcode=2016InvBi.135...75A |issn=1077-8306}}

Larvae that have grown in shallow water differ from larvae that grow in deeper water. The key difference is in the setation of the endopodite of the maxilla.{{Cite journal|date=1976|title=Studies On the Western Atlantic Arrow Crab Genus Stenorhynchus (Decapoda Brachyura, Majidae) I. Larval Characters of Two Species and Comparison With Other Larvae of Inachinae 1)|journal=Crustaceana|volume=31|issue=2|pages=157–177|doi=10.1163/156854076x00198|issn=0011-216X |last1=Won Tack Yang |bibcode=1976Crust..31..157W }}

• Decorator crab

{{Reflist|32em}}

• {{Commons category-inline|Stenorhynchus seticornis|Stenorhynchus seticornis}}
• {{SealifePhotos|421957}}

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Category:Majoidea

Category:Crabs of the Atlantic Ocean

Category:Crustaceans of Brazil

Category:Crustaceans described in 1788