The crab keeps blowing bubbles because the crab is breathing. Crabs need to keep their gills moist so they can breathe properly. When on land, crabs only use water stored in their gills to keep their gills moist, allowing them to breathe. Crabs, on the other hand, take in air when they breathe and then expel the waste gas through their gills. The expelled gas passes through the gills and combines with the water in the gills to form bubbles.

The crab keeps blowing bubbles because the crab is breathing. Crabs need to keep their gills moist so they can breathe properly. When on land, crabs only use water stored in their gills to keep their gills moist, allowing them to breathe. Crabs, on the other hand, take in air when they breathe and then expel the waste gas through their gills. The expelled gas passes through the gills and combines with the water in the gills to form bubbles.