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.
Small fish and jellyfish will eat blue crab larvae, while birds, mammals and larger fish will eat older crabs. The biggest predators of blue crabs are humans. Commercial crabbing and loss of habitat have dramatically decreased some blue crab populations. The Chesapeake Bay had a heavy decline in the 1990s, going from a high of nearly 800 million crabs in 1992 to about 250 million in 2000.