The Arrow Crab, also known as Stenorhynchus seticornis or Yellowline Arrow Crab, is a type of marine crab that lives in the ocean.
Its body is triangular, and it has a long pointy snout called a rostrum. Their legs are also long and thin, and they can be up to 3.9 in (10 cm) across.
The crab’s carapace, or outer shell, can be up to 2.4 in (6 cm) long.
What Colors Can Arrow Crabs Be?
Arrow Crabs have different colors, such as golden, yellow, or cream. They also have brown, black, or iridescent-blue lines on their bodies.
Their legs can be reddish or yellow, and their claws are blue or violet.
These colors help them blend in with their surroundings and protect them from predators.
Where Do Arrow Crabs Live?
Arrow Crabs are found in the western Atlantic Ocean, from North Carolina to Argentina.
They live in shallow areas near the bottom of the ocean, on rocks, corals, and other surfaces.
They are also found on soft sediments like shelly gravel and sand. They usually live on coral reefs at depths of 10 to 30 feet (3.0 to 9.1 m).
What Do Arrow Crabs Eat?
Arrow Crabs are nocturnal, which means they are active at night. They eat small feather duster worms and other invertebrates that live on coral reefs.
Some people keep Arrow Crabs in their reef aquariums to help control bristle worm populations.
How Do Arrow Crabs Behave?
Arrow Crabs are territorial and prefer to avoid sunlight. They change their location during the day and nighttime.
They also sometimes decorate their bodies with materials to camouflage themselves or to scare off predators.
Arrow Crabs have been known to live in association with sea anemones, such as Lebrunia danae, along with other creatures like Pederson’s cleaning shrimp and spotted cleaner shrimp.
What Is the Arrow Crab’s Life Cycle and Reproduction Process?
When Arrow Crabs mate, the male places a spermatophore, or packet of sperm, on the female, which she uses to fertilize her eggs.
The female then carries the fertilized eggs on her pleopods, or swimming legs, until they are ready to hatch into zoea larvae.
These larvae swim toward the ocean surface and feed on plankton.
They grow through a series of moults, or shedding their outer shells, and eventually change into adult crabs.
What Factors Affect the Arrow Crab’s Breeding Period?
Climate plays a major role in determining the breeding period of Arrow Crabs.
Seasonal changes in water temperature and sunlight duration are important factors.
The size of the female crab also affects the number of eggs per batch, with larger females producing more eggs.
How Do the Larval Stages of Arrow Crabs Differ?
Larvae that grow in shallow water have differences in their body structures compared to those that grow in deeper water.
The main difference is in the setation, or arrangement of bristles, on the endopodite, a part of their maxilla, or jaw-like structure.
What Is the History of Arrow Crab Classification?
The Arrow Crab was first described by Johann Friedrich Wilhelm Herbst in 1788 as Cancer seticornis.
Later, it was also described as ‘Cancer sagittarius’ by Johan Christian Fabricius in 1793, but this name is now considered a junior synonym of S. seticornis.
In 1818, Pierre André Latreille created the genus Stenorhynchus, and S. seticornis was confirmed as the type species by the International Commission on Zoological Nomenclature in 1966.
Arrow Crab Characteristics
| Reef Safe? | With caution |
| Temperament: | Unknown |
| Care Level: | Unknown |
| Maximum Size: | Unknown |
Scientific Classification
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Malacostraca |
| Order: | Decapoda |
| Family: | Inachidae |
| Genus: | Stenorhynchus |
| Scientific Name: | Stenorhynchus seticornis |
| Also Known As: | Arrow Crab, Yellowline Arrow Crab |
| Conservation Status: | Unknown |