The world's largest insect family

The Singapore stick insect is the longest insect in the world. Its slender body is 27 centimeters long. If it fully stretches its body in a quiet state, it can exceed 40 centimeters in length. The protective shape and color of the stick insect make it look real when it is inhabiting the jungle.

The Amazon giant longhorned beetle and the giant-toothed longhorned beetle are the largest beetles in the world. They are 18 cm long. The horns (long jaws) of the Big-Toothed Beetle are specially designed for cutting branches. When it hooks the branches with its sharp horns, it rotates 360° around the branches until it cuts the branches.

The Spodoptera exigua, which grows in South America, is 9 cm long and has wings 27 cm wide. Its body color is gray with dark spots. They are the largest insects among butterfly moths in the world.

Bones growing outside the body

Generally, the bones of animals are wrapped by muscles, and the muscles are covered with skin, feathers or fur, so that the bones are "contained but not exposed" inside the body. But the bones of some animals are exposed on the surface of the body. For example, when we eat shrimps and crabs, the shrimp skins, crab shells, and crab claws that make us feel uncomfortable are their skeletons. This shell composed of chitin gives the shrimps and crabs a tough "steel helmet." Because they grow outside the body, they are called exoskeletons. "The golden cicada sheds its shell", the shell that the golden cicada sheds is its outer skeleton. Then the horns, nails, hooves, and scales of some animals are also hard objects that grow outside the body. Are these also called exoskeletons? It is generally believed that only the bones of arthropods are called exoskeletons, and other animals have some hard structures on the surface of vertebrates. It is a derivative of skin.

The exoskeleton of arthropods adds a thick and hard protective shell to their bodies. The muscles attached to the exoskeleton can complete various actions driven by the bones. This thick shell can also limit water evaporation and prevent toxic substances from invading the body, creating conditions for arthropods to successfully transition from aquatic habitats to land. But after all, the exoskeleton of arthropods is composed of secretions from some cells on the body surface. The components that make up the exoskeleton are some dead substances, so it is a relatively primitive and simple type of skeleton. The "hidden" internal skeleton in the body of vertebrates is developed from some specialized tissues during embryonic development and is composed of living tissues. Naturally, various functions greatly exceed those of exoskeletons.

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