Noah had to not only put the animals on the Ark, but also their food. For example, consider the elephants. There are three species, with a male and female of each, for six elephants on board. Each one eats about 500 pounds of food per day, which requires 60 tons of food for a brief forty-day cruise. For the full five or seven months (depending on your tradition), this could mean up to 315 tons of food just for the elephants. The largest elephant on record weighed 13 tons, so the food weighs at least four times as much as the elephants themselves. And this is for just one type of animal. There are also five species of rhino, two species of hippo, more than fifty species of deer, about ninety species of antelopes, plus horses, giraffes, camels, pigs, cattle, sheep, and more, just in the ungulates. All of those will require large amounts of food, too. And we haven't even gotten to the carnivores, rodents, marsupials, and all the other mammals. Plus all the birds, reptiles, and amphibians. Plus the snails, slugs, land crabs, spiders, and a simply huge number of insects (remember, 350,000 species of beetles alone!).
An additional logistics problem is that many of these diets are so highly specialized, and the proper food must be obtained for each animal. Humans and pigs are so atypical, in that we will eat nearly anything. There are animals that feed only on the material of a single type of plant, so the vast job of collecting and maintaining all those different plants, from all over the world, would exceed the capability of any quartermaster system in existence today, with all of our technological resources. How did Noah accomplish it? For Genesis states that he was to load the Ark with not only the animals, but also their food. Wow!