More research is proving that the theory of animals becoming bolder with climate is correct. Sea water is retaining more carbon dioxide. This is altering the body chemistry of some animals.
Tests were done on the hermit crab and a "toy" of its main predator the octopus. In a laboratory, hermit crabs were split into two group and put into aquariums. The water in one aquarium was at a pH of 7.6; the other had a pH of 7.1. This may seem to be only a small amount of difference in acidity but it was significant on behavior.
The flicking of antennae (testing for danger of preying animals) and oxygen levels were measured. The hermit crabs in the more acidic pH 7.1 water flicked their antennae less often. Crabs in the 7.6 aquarium definitely responded much quicker when a toy octopus was dipped into the water.
Visitors at the Third International Symposium on the Ocean in a High-CO2 World had a good laugh at the crab behavior. A more serious problems could be the declining level of safe hermit crab abodes. Higher acidity is dissolving abandoned shells that hermit crabs jump into and carry around as homes.