When most people think of the wiggly jello mold they're probably not thinking about bones, even though that's a primary source of gelatin, the ingredient that gives jello it's structure. It is created from the collagen in animal bones and other body parts. Collagen is a protein that plays many roles inside the body and has many other uses as well.
Uses for Gelatin
While gelatin is probably most associated with food, especially dessert, it has many non-culinary uses as well. Gelatin is used in the production of glue and photography film. It's also used in many cosmetics. Even the theater has a use for gelatin in the form of colored "gels" that change the color of theater lights. Many medications use gelatin to create easier to swallow pills often called "gel-caps".
While many people have no moral or health concerns about the use of animal ingredients those that are vegan or vegetarian and even some religious groups choose not to incorporate it into their diet. Gelatin isn't just for jello though, it's also used as a thickening agent in things like yogurt or certain sauces. Those who want to avoid animal products should get used to searching for this ingredient on nutrition labels as its use in products isn't always readily apparent. Thankfully, vegans and other like-minded individuals don't have to give up things like jelly to meet their dietary needs there are vegan forms of gelatin available.
Gelatin Varieties and Types
Other forms of gelatin exist to meet the needs of those wishing alternatives to meat products for various reasons. Those of the Jewish and Islamic faith may eat animal gelatin only if it is extracted from permitted animals which have undergone ritual slaughter and excludes some forms including those made from pigs and certain types of fish. Unfortunately, store-bought foods tend not to list what animals their gelatin came from. People wishing to avoid only certain animals should probably stick to homemade recipes using one of the gelatin varieties listed below.
Isinglass is a type of gelatin extracted from the air bladders of certain fish, particularly sturgeon, but is rarely used these days.
Carrageen, also known as Irish moss, is a gelatinous thickening agent derived from seaweed which grows off the coast of Ireland. Irish moss is often used in making homebrews and meads.
Agar (also agar-agar, kanten and Japanese gelatin is a dried seaweed sold in blocks, powder, and strands which are used as a setting agent.
Agar has stronger setting properties than gelatin, so use less when substituting.
Pectin occurs naturally in fruits and vegetables and is used in the preparation of jams, jellies, and preserves. Gelatin can also be extracted from fish bones.