Hermit crab migrations

Pam St John USVI · Post by **Pam St John USVI** » Mon Aug 26, 2013 8:19 am

Hi,I live on ST John in the US Virgin Islands. Last year I stumbled upon a massive hermit crab migration and called my friend to film it - http://vimeo.com/48466065. It went viral because this migration has not be well researched or documented. I am now working with Tufts University and New England Aquarium scientists and I managed to see another migration this year. However, all of our theories were shot down by this years observations. I need help from any of you who have knowledge of hermit crab reproduction. Please contact me.ThanksPamST John US Virgin Islands

Nnnnnnnn · Post by **Nnnnnnnn** » Mon Aug 26, 2013 8:41 am

We've seen this a few times before, awesome video, and even more so that you got to see it in real life! What are your questions about hermit crab reproduction? We have a member here called Curlz that has successfully raised zoea into the land stage in captivity, only one of very few people to have completed this feat. What exactly are your questions about hermit crab reproduction?

Pam St John USVI · Post by **Pam St John USVI** » Mon Aug 26, 2013 9:10 am

I have lots of questions! We are talking about Coenobita clypeatus.How long is the gestation period for the eggs to be ready to go into the water?I saw a bubbly fluid being forced from one crab into another's body cavity - I assume this is sex? Has anyone else seen this behavior?I am trying to figure out when the migration happens. Last year it was on Aug 28, 4 days after the 1st quarter of the moon, 3 days before the full moon. This year's large migration was on August 22, 7 days after 1st quarter of the moon, 1 day after the full moon.So that theory is shot. And one site migrated on a completely different day than another site.Can any of you pinpoint sex and/or putting the eggs into water better?The method used to get the eggs in the water was for the crab to go up to the surf line, pick a good holding on spot, then wait for the waves to wash over it. While under water it pumped its shell up and down, flushing the eggs out. Has anyone else seen this?Since it took some time for the eggs to mature, I assumed that the sex happened up in the hills and only the females made the long trek to the ocean. All tests on individual crabs resulted in females with eggs. There was no shell swapping or sex going on leading up to the mass migrations (tens of thousands) but after almost all of the activity stopped for the day of the migration, there were a handful of crabs exchanging the bubbly fluid. If this is sex, then there have to be some males around.And does this mean those poor females are going to have to go back in the ocean again in a few weeks when the new eggs are ready?To make things even more confusing, all previous reports of these mass migrations were single day occurrences, but this year the bug day was August 22nd, but there have still been crabs entering the water each morning since then. What's up with that?Any help would be appreciated and I have lots of pictures and videos that I can share.PamThere is also a site near a salt pond that had absolutely no crabs, then 2 days later on August 22nd there were hundreds of crabs hanging out just at the waters edge - not going into it, just staying at the edge. They are still there today. Certainly not females putting eggs into the water (in is an inland pond). Any ideas?

peruvian0299 · Post by **peruvian0299** » Sat Sep 07, 2013 4:02 pm

That was the best thing i have ever seenin my entire life

Nicole · Post by **Nicole** » Wed Sep 11, 2013 6:26 am

Pam, here is a site that can hopefully answer some of your questions about crab reproduction: http://www.hermitcrabpatch.com...Life-Cycle-a/152.htmCrabs must drink brackish water and/or salt water in addition to fresh water so that may have been the other behavior you witnessed at the pond.