[Venividivici (OP)]

Soldier crabs, or specifically light-blue soldier crabs (Mictyris longicarpus) have both lungs and gills (albeit only 5 gills). 90% of their oxygen intake comes from their lungs. When their burrow collapses during high tide and the ocean water fills their burrow, they drown. Why? Is this because their gills are not powerful/efficient enough to supply them with sufficient oxygen?

might be a helpful link:
newbielink:http://www.gbri.org.au/SpeciesList/Mictyrislongicarpus%7CKateBuchanan.aspx?moid=813&PageContentID=5035 [nonactive]

[Don_1]

As an air breathing crab, they cannot sustain prolonged periods submerged.

This article may be of interest to you.
http://jeb.biologists.org/content/187/1/113.full.pdf