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Stenorhynchus seticornis (Arrow Crab )
Stenorhynchus seticornis, commonly known as the yellowline arrow crab or simply arrow crab, is a fascinating marine species renowned for its distinctive features. One striking characteristic is its elongated, spider-like legs, which are more than three times the length of its body, reminiscent of a daddy long-legs spider. The crab’s body itself displays a captivating medium golden brown hue, adorned with stripes varying in color from white to brown or gold, depending on the individual. Adding to its allure, the tips of its legs boast a deep violet hue.
During growth, these crabs undergo molting, a process where they shed their exoskeleton to accommodate their increasing size. The newly exposed skin then hardens with calcium carbonate, obtained from both seawater and the ingestion of the old shell.
Found commonly in the Caribbean Sea, particularly around the island of Curaçao, yellowline arrow crabs prefer the cover of darkness, being nocturnal creatures. However, with a keen eye and a flashlight, observers can easily spot them tucked away in crevices or beneath rocks, showcasing their intriguing behaviors in their natural habitat.
Scientific Classification
| Domain | Eukaryota |
| Kingdom | Animalia |
| Phylum | Arthropoda |
| Class | Malacostraca |
| Order | Decapoda |
| Suborder | Pleocyemata |
| Infraorder | Brachyura |
| Family | Inachidae |
| Genus | Stenorhynchus |
| Species | S. seticornis |
Taxonomy
Stenorhynchus seticornis, initially documented by Johann Friedrich Wilhelm Herbst in 1788 as Cancer seticornis, and later referred to as “Cancer sagittarius” by Johan Christian Fabricius in 1793, a designation now recognized as a junior synonym of S. seticornis. The genus Stenorhynchus was formally established by Pierre André Latreille in 1818, albeit initially misspelled as Stenorynchus. In 1966, the International Commission on Zoological Nomenclature affirmed S. seticornis as the type species. These taxonomical details provide a comprehensive understanding of the historical context and classification of this intriguing marine crab species.
Binomial name
Stenorhynchus seticornis (Herbst, 1788)
Description
Stenorhynchus seticornis, known for its distinctive triangular body and elongated rostrum with serrated edges, exhibits striking physical features. The legs of this species are notably long and slender, reaching up to 10 cm (3.9 in) across, while the carapace can measure up to 6 cm (2.4 in) in length. Its coloration varies, ranging from golden, yellow, to cream, adorned with intricate patterns of brown, black, or iridescent-blue lines. Notably, the legs showcase hues of reddish or yellow, with claws often boasting blue or violet tips. These diagnostic traits, including the triangular body, fine dark lines on the carapace, and violet-tipped claws, distinguish Stenorhynchus seticornis. In south-eastern Brazil, it is commonly associated with anemones, often found in groups ranging from one to six individuals.
The yellowline arrow crab stands out for its unique characteristics, particularly its long, spider-like legs and sharply pointed head. With legs extending more than three times the length of its body, reminiscent of a daddy-long-legs spider, this crab boasts a medium golden brown body hue. Dorsally, it displays stripes varying in color from white, brown, to gold, with deep violet tips accentuating its legs. Molting is a regular occurrence as these crabs grow, with their new skin hardening through the intake of calcium carbonate from seawater and ingested old shells.
Often referred to as the spider crab, the arrow crab, specifically Stenorhynchus seticornis, captivates observers with its elongated legs and peculiar head protrusion. This species, commonly recognized by its yellow lines atop its rusty-colored extremities, can attain a considerable size, with a leg span reaching around 8 inches, roughly equivalent to the size of an adult’s hand. Notably, females typically remain smaller than males, adding to the intriguing dynamics within this species.
