Grasshoppers do not possess backbones. Unlike humans and many other animals, their structural support comes from an external covering. This rigid outer layer, known as an exoskeleton, serves as both their skeleton and protective armor.
The Grasshopper’s Outer Armor
A grasshopper’s exoskeleton is a multi-layered structure that provides support and protection. It is primarily composed of chitin, a tough, fibrous polysaccharide, along with various proteins, creating a strong yet flexible casing. The exoskeleton encases the grasshopper’s entire body, offering structural rigidity and safeguarding its internal organs. It also helps to prevent water loss, important for terrestrial insects.
The exoskeleton is not a single, continuous piece but is segmented, allowing for movement. Each segment is made of hardened plates, called sclerites, connected by thinner, more flexible membranes at the joints. This design is highly efficient for small animals, providing a large surface area for muscle attachment.
How Grasshoppers Move and Grow
The exoskeleton plays a central role in a grasshopper’s movement and growth, despite its rigid nature. Muscles attach to the inner surface of the exoskeleton, forming a lever system that enables locomotion. For instance, the powerful hind legs, specialized for jumping, contain large muscles that pull on tendons connected to the exoskeleton, allowing for rapid extension. This internal muscle attachment provides the force needed for their characteristic leaps and walking.
Because the exoskeleton is a hard, unyielding shell, it cannot grow as the grasshopper grows. To increase in size, grasshoppers must periodically shed their old exoskeleton in a process called molting, or ecdysis. During molting, the grasshopper develops a new, soft exoskeleton underneath the old one, then sheds the old casing. This process leaves the grasshopper temporarily vulnerable until its new exoskeleton hardens, which can take some time. Most grasshoppers undergo about five to six molts, or instars, before reaching their adult size and developing fully functional wings.
Animals With and Without Backbones
In the broader animal kingdom, organisms are categorized based on the presence or absence of a backbone. Animals with a vertebral column, or backbone, are known as vertebrates. This group includes a wide array of familiar creatures such as mammals, birds, reptiles, amphibians, and fish. Vertebrates possess an internal skeleton, or endoskeleton, which provides support and protects the central nervous system.
Conversely, animals that lack a backbone are classified as invertebrates. This diverse group makes up over 90 percent of all animal species on Earth. Invertebrates encompass a vast range of organisms, including insects like grasshoppers, as well as worms, jellyfish, spiders, and mollusks. Grasshoppers, therefore, fall squarely into the invertebrate category, relying on their external chitinous armor rather than an internal bony spine for structural integrity.