Ancestor: Unknown
Evolved: Unknown
Extinct: Not yet.
Location: Thin Southern temperate strip of Catland, and the temperate and taiga zones of Nuopolarica.
Viable Habitat: Upland forest and temperate forest in clear, cool fast-flowing rivers.
Size: 6 cm
Weight: No data.
Dietary Needs: Huimified fallen vegetativeĀ matter on the riverbed and the microorganisms passively ingested with it.
Life Cycle: They are much less metabolically active in cold, winter months and do not moult or reproduce during this time. During the summer males compete with other males to mate with females and have larger chelipeds to fight with than the females. Males leave spermatophores which females carry to fertilise her eggs. However this spermatophore is lost with every moult the female has. Each time she must mate again some time afterwards to have fertilised offspring.
Females practice brood care and protect their offspring independently of the male. Eggs and young are attached to the underside of the mother's abdomen by a telson thread, which dissolves after the larva's first two moults. The female's abdomen is wider for this purpose and her pleopods are more paddle-like to act as a shield for her offspring. In males these pleopods are reduced. Unlike many decapods, C. japonicus have no free-living larval stage, this stage completes inside the egg. Young hatch resembling miniatures of the adults.
The rate of juvenile maturation is dependant on temperature. At the warmest of it's range juveniles might mature by the next year on Planet Cat Sanctuary. At the coldest latitudes (and sometimes highest elevations) the juveniles won't be ready to reproduce as an adult until not the next year but the year after.
Other: For moulting and general safety they occasionally make underwater burrows in the river sediment. However they can also use natural shelter such as rotted logs. Crayfish have calcium-hardened exoskeletons and cannot grow inside it. Crayfish growth relies on moulting, as their new exoskeletons are soft and expand into their new size before they harden. However this post-hardening phase leaves them entirely helpless for a short time.
They may use posturing displays to look big and ward off a threat, and their claws can also assist in their defence. However if they are really threatened they can use a flick of their tail to propel themselves backwards in a motion known as "lobstering".