Life Cycle

Graceful Decorator Crab's live a solitary existence throughout the majority of their lives.  Between the months of May and August, however, is the season in which large planktonic blooms form causing the crabs to come together and mate with one another (Larson 2013).  Chemical cues released from the crabs have been identified as a main driving force behind their searching for a partner (Ever Green 2011).  Once a companion has been located, males use their abdominal appendages to grasp on to the female and dispatch their sperm (Ever Green 2011).  This sperm lacks flagella making it nearly impossible for them to reach the eggs on their own.  Thus, they are transferred through the aide of spermatophores, a type of packaging injected directly into the female crab (Cattle Point 2010).  Once fertilization of the eggs has been completed, they are fastened to the females abdominal setae using a tacky secretion produced from their mouths.  By frequently aerating the eggs and removing foreign bodies, the females help keep them healthy and developing properly.  

                While maturing within the egg, the embryos progress through the naupliar stage and hatch as a more advanced larval stage known as a zoea.  At this point the crab larvae possess compound eyes and a spiny carapace.  These miniscule organisms are swept up into the water column and assimilated into immense pelagic plankton blooms (Cattle Point 2010).  Compared to the other zooplankton found in these blooms, the Oregonia gracilis larvae are quite agile due to their maxilipeds.  While feeding amongst the plankton, these zoea develop into a stage known as megalopa.  Their appearance throughout this stage bares a strong resemblance to the adult crab, with the main variation being that the abdomen is not yet beneath the thorax.  This is also the final phase before the crab reaches adulthood, or the benthic stage.

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