Arrow crab
Encyclopedia
Stenorhynchus seticornis, the yellowline arrow crab or simply arrow crab, is a species
of marine crab
.
is drawn out into a long point with serrate edges. The legs are also long and thin, up to 10 cm (3.9 in) across, and the animal's carapace
may be up to 6 centimetres (2.4 in) long. 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 claw
s are blue or violet.
, from North Carolina
and Bermuda
to Brazil
, including throughout the Caribbean Sea
. It lives on coral reef
s at depths of 10–30 ft (3–9.1 ).
and other coral reef invertebrate
s. They are commonly kept in reef aquariums to control bristle worm population.
, 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.
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. 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.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of marine crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
.
Description
The body of S. seticornis is triangular, and the rostrumRostrum (anatomy)
The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....
is drawn out into a long point with serrate edges. The legs are also long and thin, up to 10 cm (3.9 in) across, and the animal's carapace
Carapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
may be up to 6 centimetres (2.4 in) long. Colouration is variable in this species: the body may be golden, yellow or cream, marked with brown, black or iridescent
Iridescence
Iridescence is generally known as the property of certain surfaces which appear to change color as the angle of view or the angle of illumination changes...
blue lines; the legs are reddish or yellow, and the claw
Claw
A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. However, the word "claw" is also often used in reference to an invertebrate. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end...
s are blue or violet.
Distribution
Stenorhynchus seticornis is found in the western Atlantic OceanAtlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, from North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
and Bermuda
Bermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
to Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, including throughout the Caribbean Sea
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....
. It lives on coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...
s at depths of 10–30 ft (3–9.1 ).
Ecology and behaviour
S. seticornis is nocturnal and territorial. It eats small feather duster wormsSabellidae
Sabellidae are sedentary marine polychaete tube worms where the head is mostly concealed by feathery branchiae. They build tubes out of parchment, sand, and bits of shell...
and other coral reef invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s. They are commonly kept in reef aquariums to control bristle worm population.
Life cycle
During matingMating
In biology, mating is the pairing of opposite-sex or hermaphroditic organisms for copulation. In social animals, it also includes the raising of their offspring. Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization...
, the male places a spermatophore
Spermatophore
A spermatophore or sperm ampulla is a capsule or mass created by males of various animal species, containing spermatozoa and transferred in entirety to the female's ovipore during copulation...
on the female, which she uses to fertilise her eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
. 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
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
. They grow through a series of moults
Ecdysis
Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...
, and eventually metamorphose into the adult form.
Taxonomic history
Stenorhynchus seticornis was first describedAlpha taxonomy
Alpha taxonomy is the discipline concerned with finding, describing and naming species of living or fossil organisms. This field is supported by institutions holding collections of these organisms, with relevant data, carefully curated: such institutes include natural history museums, herbaria and...
by Johann Friedrich Wilhelm Herbst
Johann Friedrich Wilhelm Herbst
Johann Friedrich Wilhelm Herbst was a German naturalist and entomologist from Petershagen, Minden-Ravensberg....
in 1788, under the name Cancer seticornis. It was also described as "Cancer sagittarius" by Johan Christian Fabricius
Johan Christian Fabricius
Johan Christian Fabricius was a Danish zoologist, specialising in "Insecta", which at that time included all arthropods: insects, arachnids, crustaceans and others...
in 1793, a name which is now a junior synonym of S. seticornis. Pierre André Latreille
Pierre André Latreille
Pierre André Latreille was a French zoologist, specialising in arthropods. Having trained as a Roman Catholic priest before the French Revolution, Latreille was imprisoned, and only regained his freedom after recognising a rare species he found in the prison, Necrobia ruficollis...
erected the genus Stenorhynchus
Stenorhynchus
Stenorhynchus is a genus of marine crabs in the family Inachidae, containing the following species:*Stenorhynchus debilis *Stenorhynchus lanceolatus...
(originally mis-spelt Stenorynchus) in 1818, and S. seticornis was confirmed as the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
by the International Commission on Zoological Nomenclature
International Commission on Zoological Nomenclature
The International Commission on Zoological Nomenclature is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 28 members from 20 countries, mainly practicing zoological taxonomists...
in 1966.