A postcard of the Mohawk, a typical 1930s passenger liner
A liner is a vessel designed primarily to carry passengers on a set schedule. There was a time when ocean liners were more than the mere pleasure cruisers of today. Before the advent of modern air travel, ships were the primary means of transport for those needing to cross the oceans. Untold numbers of immigrants came to this country in passenger liners, most in steerage class, a far cry from the modern floating pleasure palaces.
Most of these sharks are in more danger from us than we are from them. Real sharks are ashamed of them.
"Dogfish" is a generic name for a large number of small, generally harmless, and unaggressive sharks, not all of which are very closely related. Smooth Dogfishes are related to Tiger, Bull, and other Requiem Sharks, while Spiny Dogfishes are in a completely different group, more closely related to Angel Sharks. Compare these with the unrelated Chain Dogfish, a "Cat" shark. Sandbar sharks have nothing in common with the others here, except their small size. None of these little sharks is really dangerous, although any of them could give a good bite if provoked. Generally, they will avoid you.