Nutrition

         M. differentialis is a polyphagous grasshopper that feeds predominately on a variety of plant leaves. However, it has also been known to engage in cannibalism (Bomar & Lockwood, 1994). Thanks to modern agricultural practices in North America a grasshopper doesn’t have to go far to find many of its favorite foods including: corn, soybeans, clover, alfalfa, and many small grain plants (Pfadt, 1971). Since, M. differentialis is a non-migratory grasshopper it is important that nymphs (baby grasshoppers) are born near a viable food source. Luckily pregnant females of this species favor the heavy soils in the crowns of tall grasses and along the edges of fields for egg laying (Pfadt, 1971). This ensures a close proximity to food for newly hatched offspring which can detect the nearby edible food sources with their sensitive antennae. Though this system is beneficial for the insects, their choice of host plants often puts them at odds with farmers trying to protect their crops. The voracious appetites and typical large numbers of this species often makes them the public enemy of farming communities and a target for many types of pesticides.

  

 

        Grasshoppers are heterotrophic organisms and like many other heterotrophs they have a digestive system beginning with a mouth where food is ingested and ending in an anus where food is expelled. However, unlike many familiar digestive systems, like humans, a grasshopper has several additional digestive structures that aid in nutrient uptake.

       Digestion occurs in several steps. First grasshoppers use their vertically parallel mandibles to strip pieces of leaves from a plant. Once inside the mouth the food is met with salivary enzymes, which begin to breakdown the plant matter and provide lubrication as the food is swallowed. The pulverized food then enters the crop, an organ absent in the human digestive tract, where it is temporarily stored and prepared for digestion. Once prepared the food moves into the gizzard. In the gizzard the food is ground up in what can be considered a second chewing stage. The gizzard is an important structure, because grasshoppers lack an efficient chewing mechanism in the mouth like molar teeth in humans. After the food is sufficiently masticated it travels to the stomach where it is met with a variety of digestive enzymes. The digestive enzymes help to break down the food and allow the nutrients to be absorbed through the lining of the stomach and transported to various parts of the body. Final nutrient and water uptake occur in the hindgut before the undigested plant matter is formed into fecal pellets and expelled from the posterior anus.

Internal Food and Water Transport

         Grasshoppers have an open circulatory system meaning that instead of being bound by veins and arteries the heart pumps blood into open spaces or sinuses within the body. The blood is the main method of nutrient and water transfer from the digestive system to the rest of the body. Unlike mammals a grasshoppers blood is colorless because it lacks the metalloprotein hemoglobin. The lack of hemoglobin means that the insects’ blood is not used in gas exchange. Instead air is transported directly into the body through tracheal tubes that appear as small holes in the animals’ exoskeleton. The small holes, or spiracles, lead to a series of branching tubes that carry oxygen directly to cells where gas is exchanged. Muscle contractions in tiny air sacks maintain a constant flow of air throughout the branching tracheal tubes.

How is food stored?

         Like many other animals grasshoppers store any excess food as lipids or fats within the body. This storage method is most apparent in the larval stage of the grasshopper, where body size is largely determined by fat storage (http://www.ncbi.nlm.nih.gov/pubmed/16098985).

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