Ranitidine is a competitive, reversible inhibitor of the action of histamine at the histamine H2-receptors, including receptors on the gastric cells. Ranitidine does not lower serum Ca++ in hypercalcemic states. Ranitidine is not an anticholinergic agent.
1 The Blue Marlins have a diet of: Octopi, squid and pelagic fish such as black fin tuna and frigate mackerel.  They do prefer to hunt alone and during the day, rather than in schools, so it is safe to say they are a rather antisocial species.
Some species have been known to eat guano (bat droppings).   Different species of crabs eat different foods. Depending on the species, they may eat plankton, worms, shrimps, prawns and other shellfish, and they scavenge for animal and/or plant remains.