Lifecycle

Zoea, megalops and the adult decapod are the three main stages of development of the lifecycle of the Paralithodes camtschatica.

When there are two stages of larval development occur, the beginning life of a red king crab starts inside the egg. Zoea is the newborn king crab which hatched by the eggs of the Paralithodes camtschatica. It is carried along by the ocean currents, acting as free swimming organisms. The zoea does not resemble the adult decapod, differing from the true crab form by having a tail, or telson, and also having feathered limbs instead of clawed limbs. After it undergoes metamorphosis, these characteristics will all change. Though four developmental stages during the first two to four months, the zoea is adapted for swimming by molting up to five times, each time increasing its size, form, and functions. However, it has not got enough power to against the ocean currents yet. It is risky to be swept away from the parental grounds to an unknown destination. Thus, it will be absolutely excellent for the zoea if it can end up in a good habitat which there’s full of food and away from much predation.

From:http://aqua-online.org/pictures/crab-larvae.jpg

Fig.7.Stage1——Zoea.   From:http://aqua-online.org/pictures/crab-larvae.jpg

Megalops is the second stage of the red king crab’s growth, where the feathered limbs are now clawed limbs and the juvenile crab now more closely resembles the adult while the the abdomen is still prominent and the crab is about an eighth of an inch. When the megalops aged around two, it develops a benthic, or bottom dwelling lifecycle and also develop a good system with special colonial characteristic called podding which means the vulnerable juvenile crab can protect each other by forming large groups of individuals at shallow depths. In virtue of the massive groups, even the megalops has not been highly armored like the adult, its mortality is not much high. Staying in the podding makes the predator have to find them first and saves many from predation because the predator can only eat so many. Although the time the crab is most susceptible to predation, large groups still offer help during the molting season. In short, the megalops stage can last up to 4 years and then the crab passes onto adulthood.

crab-juvenile

Fig.8.Stage2——Megalops. From:http://bioweb.uwlax.edu/bio203/s2007/luchsing_sara/reproduction_and_lifecyle.htm

The last but not least stage of the red king crab’s growth is migrating to the depths of about 200 meters or below of the ocean. The adult decapod is heavily armored with a hard calcified carapace and with sharp spines extending from the shell. Few predators will eat the adult decapod, so it is free to roam the ocean floor. There’s an interesting fact that the adult decapods are segregated by sex when in their deep environment. And not until the mating season comes in the spring do they then come together. The adult decapod keeps growing and molting every time with no life limitation except being overfishing.

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Fig.9.Stage3——Adult decapod. From:http://www.nordnorge.com/en/boat-and-water/?News=19

 

 

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