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Saturday, July 21, 2012

An exceptional spine

If you haven't yet seen the larval stage of a porcelain crab, you've been missing out!  

On 18 July, I posted a picture of an adult porcelain crab.  Tonight's post features the larval swimming stage called a zoea.  The larva looks nothing like the adult.  

Porcelain crab zoea spend ~40 days in the plankton, molting several times before becoming a megalopa — the last larval stage before transforming into a benthic (bottom-dwelling) juvenile crab.

Note (not that you won't!) the exceptionally long inflexible spines.  The forward-projecting spine is called a rostral spine.  It's thought that this spine deters potential fish predators.  Here's a close-up:

 For scale, this zoea was ~2 cm long — remarkably long for a larval crab.
This porcelain crab zoea was collected in a plankton tow near Bodega Rock (off the southern tip of Bodega Head) on 16 July 2012.

If you were a fish, would you try to eat this larva for dinner?

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