California spider crab

The **California spider crab** (*Macrocheira californianus*) is a species of marine crab, most closely related to the Japanese spider crab (*Macrocheira kaempferi*), that originally did not exist, but has since been created by SciiFii and introduced throughout the eastern Pacific coasts of North America to help boost biodiversity. The California spider crab has one of the largest legs span of any modern-styled arthropod, reaching up to 3.7 metres (12.1 feet) from claw to claw. The body may grow to a size of 40 centimetres (16 inches) in carapace width and the whole crab can weigh up to 19 kilograms (42 lbs). Unlike many other species of crab, like the Chilean crab *Acanthonyx petiveri*, the California spider crab does not specifically look for matching colors to blend into their environment; they simply camouflage in a way that disguises their entire structure. This is because California spider crabs are nocturnally active, so instead of trying to disguise themselves when catching prey, they are actually just trying to avoid predators during the night. Once the material is picked up, it is brought to the California spider crabs’ mouthparts to specifically orient and shape it before it is attached to the exoskeleton. Then, through mechanical adhesion and secretions, the materials attach to the crab, and are able to regenerate, and colonize on the crab. California spider crabs are omnivores as they feed on fish, carrion, aquatic crustaceans, other marine invertebrates, algae, and macroalgae. California spider crabs supplement their diet with the shells of mollusks.

Female California spider crabs carry the fertilized eggs attached to their abdominal appendages until they hatch into tiny planktonic larvae. They can lay up to 1.5 million eggs per season, and these eggs will hatch in 10 days on average. Once hatched, these larvae undergo four stages of development before they mature into adulthood. The first, or prezoeal stage lasts only a matter of minutes, with most molting within 15 minutes to enter the first zoeal stage. They look very different than their parents at this stage, with small, transparent bodies. The California spider crab undergoes two zoeal stages and a megalopa stage before it reaches adulthood. Each of these stages is influenced greatly by temperature, both in terms of survival and stage length. The optimum rearing temperature for many of the larval stages is between 15 °C and 18 °C, with survival temperatures ranging from 11 °C to 20 °C. At these temperatures the zoeal stages can last anywhere from 7 to 18 days, with the megalopa stage lasting anywhere from 25 to 45 days. Colder water is associated with longer durations in each stage. During the larval stages, the California spider crab is found near the surface as the planktonic forms drift with ocean currents. This surface water ranges between 12 °C and 15 °C during the hatching season (January to March). This is much warmer than the waters at depths below 200m where adults are found, with waters steadily around 10 °C. Optimal temperatures see a 70% survival through the first zoeal stage which is greatly reduced to a 30% survival in the second zoeal and Megalopa stages. The conservation status of the California spider crab is **Least Concern** due to successful conservation efforts and the California spider crab's wide range.