About 200 years ago, the lobster was regarded by most Americans as a filthy, bottom-feeding scavenger unfit for consumption by civilized people. Frequently ground up and used as fertilizer, the crustacean was, at best, poor people’s food. In fact, in some colonies, the lobster was the subject of laws — laws that forbade feeding it to prisoners more than once a week because that was “cruel and unusual” treatment.

Things obviously changed for the one-time prisoner’s grub. It’s a gastronomic delicacy, the star of festivals, subject of odes to New England summers, a peer of prime rib.

The rise of lobster (as described in David Foster Wallace’s brilliant Gourmet piece “Consider the Lobster“) is a tale of hope, a shining example of triumph over the yuck factor.

Much of the conversation about how to solve the coming food crisis caused by soaring population, diminishing resources and a warming planet focuses rightly on technology, reducing waste and improving food access and distribution methods. But equal urgency needs to be devoted to simply broadening our appetites. Two food sources that strike many as unpalatable — insects and seaweed — could play a critical role in not only feeding the 2.5 billion extra humans expected by 2050, but doing so in a green, climate-friendly way.

With the exception of honey (bee vomit), insects pretty much reside in “Fear Factor” and “Bizarre Foods” country. If you’re not familiar with the bug-food phobia, consider March’s Frappuccino incident. A barista revealed that Starbucks was using cochineal beetles to color its strawberry frap, prompting headlines like “Starbucks Lovers Bug Out Over Creepy Frappuccino Incident.” Within weeks, Starbucks apologized, replacing the beetle juice with tomato-extract coloring. The point: Insects are overwhelming viewed as filthy, creepy, dangerous, inedible — and not just to vegans.

But this prejudice against eating insects — four-fifths of all known organisms on earth — is slowly starting to change. A growing number of people are beginning to recognize that bugs, such as mealworms, grasshoppers and crickets, may be the ultimate sustainable protein source. In January 2012, the United Nations Food and Agriculture Organization held an insect summit of sorts — 37 international experts gathered in Rome to discuss the role of insects in achieving global food security.

Many insects are what you might call superfood — rich in protein, low in fat and cholesterol, high in essential vitamins and minerals like calcium and iron. More important, insects are green super-foods. Bugs are cold-blooded (they don’t waste energy to stay warm), so they’re far more efficient at converting feed to meat than cattle or pigs. Ten grams of feed produces one gram of beef or three grams of pork, but it can yield nine grams of edible insect meat, according research from Arnold van Huis, an entomologist at Wageningen University in the Netherlands. Yet insects still have virtually the same amount of protein as beef or pork. A 100-gram portion of grasshopper meat contains 20.6 grams of protein, just 7 grams less than an equivalent portion of beef.

If the protein numbers and energy efficiency don’t move you to try a grilled locust, consider this: Insects use a fraction of the water and land of conventional livestock, plus they’re climate-friendly. According to van Huis’ research, breeding edible insects, like locusts and crickets, emits just 10 percent of the methane from livestock and about 0.3 percent of the nitrous oxide. Insects are also natural recyclers that thrive on paper and industrial wastes — stuff that would normally be trashed.

Insect-eating doesn’t have a yuck factor in most of the world. Venezuelans eat French-fried ants. Ghanaians eat bread made out of termites. Thailand has more than 15,000 locust farmers. As pro-bug people like to point out, 70 percent of the world’s population eats more than 1,400 insects.

Fear of insect eating is peculiar to North Americans and Europeans. Advocates of a global surge in “micro livestock” — that’s the euphemistic term some like to apply to insect farming — are trying to challenge the phobia.

The European Union has offered 3 million euros to member states that promote the use of insects in cooking. The Dutch government has given $1.3 million to support insect-husbandry research. A barbecued ant-eating festival in the Netherlands in 2006 attracted more than 20,000. You can now buy mealworms, buffalo worms and locusts — as well as products containing insects, like Bug Sticks and Bug Nuggets — at Sligro, the Dutch equivalent of Costco.

For years, a small group of American entomologists have been tireless promoting bug-eating with books like “Creepy Crawly Cuisine” and The Food Insects Newsletter, but now the foodies and entrepreneurs are helping. Award-winning chef José Andrés serves a popular chapulin taco stuffed with Oaxacan-style dried grasshoppers at his Washington restaurant Oyamel. Andrés raves about not only the mouthfeel of young crispy grasshoppers, but also their sustainability and benefit to humanity. Insect-dishes are starting to show up on daring restaurant menus — flatbread made out of roasted cricket, pan-fried locusts, stir-fried silk worm larvae and chocolate-covered scorpions. Others take a different approach: The Chicago start-up Entom Foods aims to deshell insects with a pressurization technique, so that insect meat is in cutlet form. The idea is that Americans will be more willing to embrace grasshoppers and ants if they’re unrecognizable. Get ready for mealworms shaped as hamburgers and shrimp.

The yuck isn’t the only challenge to industrial-scale insect farming. You’d have to eat roughly 100 grasshoppers to equal the amount of protein in a 12-ounce steak. But at a time when 1 billion people are chronically hungry, and when the raising of livestock already takes up two-thirds of the world’s farmland and generates 20 percent of greenhouse gas emission, class Insecta, subphylum Hexapoda needs to be more aggressively explored as a food source.

Another vastly underexplored food source, with yuck factor issues, is kelp. Now the idea of farming plants in the oceans isn’t new. In the post-World War II era, some idealistic scientists enthused about the idea of solving human food needs with a fast-growing, protein-packed algae called chlorella. Plankton soup, the food historian Warren Belasco reports, was even served at a Venezuelan leper colony.

In an eye-opening essay called “Towards a Marine Agronomy,” aquaculture consultant John Forster revives the argument that, given demographic projections, the sea must play a much greater role in food security.

Oceans are the slackers of food production — they cover more than 70 percent of the Earth’s surface, yet yield 2 percent of our food. And it’s not because we haven’t done a good job catching or growing fish.

Forster argues that the greatest promise of sustainable aquaculture isn’t in efficiently raised finfish or shellfish. Nor is it in lower-on-the-marine-chain seafood, like sardines or anchovies, as sustainability-mind chefs like Barton Seaver and Bun Lai have advocated. The panacea is at the very bottom of the marine food chain: phytoplankton.

The virtues of phytoplankton (which include algae and seaweeds) as a primary food sources are many. Kelp, a type of seaweed, is nutrient-rich, low in fat, and grows at turbo-speed. Often described as the tree of the sea, kelp grows nine to 12 feet in three months — without freshwater, deforestation or fertilizer. And because it’s the one of the fastest-growing plants on earth, kelp draws down a lot of carbon. A World Bank study showed that the production process of seaweed farms could actually have a negative carbon footprint, absorbing 20 percent more carbon dioxide than it emits per cycle. In another study, Ronald Osinga of Wageningen University estimates that just 1 percent of the Earth’s ocean surface — an area roughly the size of the state of Washington — would be needed to grow an amount of seaweed equal to all of the food plants currently farmed on land.

Marine agronomy is not a novel concept in Asia, where seaweed has long been a staple crop. Japan and South Korea have invested millions in kelp farming, while the Philippines has increased sea farming by more than 100 times in recent years.

In the United States, though, seaweed is still largely off the menu, save for an appearance as an appetizer at Japanese restaurants. That’s changing.

Seaweed is starting to appear under the more palate-pleasing names like “sea vegetables” or “sea lettuce.” Two Maine companies, Maine Coast Sea Vegetables and Ocean Approved, are introducing a host of seaweed derived products — kelp noodles, kelp energy bars, kelp pickles, seaweed-flavored tortilla chips.

Marine agronomy will inevitably contribute a larger role in the world’s food production — whether as “sea vegetables,” as livestock feed or as ingredients in processed foods.