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In our Puget Sound Beaches unit we compared the life cycle of the barnacle and the crab. We would like to know which one molts more often. We found out that barnacles go from egg to nauplius, have 5 stages to get to the cyprid stage, then continue to molt inside their plates as adults. Crabs go from egg to zoea, then have 5 stages to get to be megalopes, then molt more to become juveniles, then adults (about 12 molts the first two years, then 1 time per year after about 3 years. We still don't really know the answer to our question. Which one molts more?
Answer 1:

The number of molts for crabs is different for different kinds of crabs. the dungeness crab molts 12 times as they develop from juveniles and then once a year. Blue crabs will molt many times as they develop from juveniles and then up to 23 times as adults. The king crab will molt about 20 times in its lifetime.

Barnacles don't really molt in the same way crabs do once they have established on rocks. They do go through similar molting as they develop from juveniles but once they are adults, barnacles do not shed their whole outercoat when molting like crabs do. Instead, barnacles stick to rocks and build shell walls around themselves. They slowly add to the walls around the edges and joints so the walls slowly get larger.


Answer 2:

Which one molts more?

That depends on the barnacle and on the crab, and on the ages of both. By and large, young crustaceans have shorter time between molts than older ones.



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