Ascension : Larval land crabs
Submitted by The Islander (Conservation Office) 26.04.2007 (Article Archived on 10.05.2007)
You may remember the Conservation Weekly article a few weeks ago that described the breeding cycle of Ascension’s land crabs.
To recap, the land crabs migrate from Green Mountain down to the shoreline each year to mate and lay their eggs in the ocean. These small eggs will develop at sea for approximately 20 days. The generalized life cycle of juvenile crabs during this time includes three major stages: zoea, megalopae, and “first crabs.” The few juvenile crabs that survive to the “first crab” stage will make their way back to Ascension’s beaches and begin their ascent up the mountain.
Image: http://www.vims.edu/adv/ed/crab/cycle.html
In March, Assistant Conservation Officer Stedson Stroud discovered large numbers of mating land crabs and has been monitoring the beaches for the juvenile crabs return. Last week, Conservation staff conducted a tour of Boatswainbird Island. During the trip, Adrian Bowers, Seabird Restoration Project Fieldworker, discovered some tiny larval invertebrates on the boat. The creatures found by Adrian were small, pale in color, with large eyestalks, and a crab-shaped body with the remnants of a tail bud. Conservation staff now believe that these may be the megalopae stage of the land crabs and perhaps we’ll find the “first crabs” descending onto Ascension’s beaches in the days to come. Keep your eyes peeled for baby crabs on your boats, ropes, and on the sand and rocks!
Photo credit: Mark Pearson
By Susanna Musick
Ascension Conservation Officer
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