Open Circulatory System In Invertebrates mechanism Of Transport In Insects

Invertebrates such as hydra, flatworms, and insects are animals without backbones. Their transport mechanism is called the circulatory system, which describes the circular movement of substances. The lesson aims to explain the two main types of circulatory systems and specifically focus on open circulatory systems in insects like grasshoppers.

The circulatory system consists of the heart, blood, and blood vessels. There are two primary types: open circulatory systems and closed circulatory systems. Some invertebrates, including insects and flatworms, possess open circulatory systems.

Insects have a form of 'blood' called hemolymph. Unlike human blood, hemolymph cannot transport oxygen and is not red because it lacks hemoglobin. This is why when you step on an insect, you might see a clear or yellowish fluid, not red blood.

In grasshoppers, the tubular heart has openings called ostia (plural of ostium) on the dorsal vessel. The heart pumps hemolymph forward into the aorta. From there, the hemolymph flows into the insect's body cavity, known as the hemocoel. When the heart relaxes, the ostia open, and the hemolymph returns to the tubular heart through these openings. During this process, digested food substances are delivered to cells, and waste products are collected and moved to the Malpighian tubules for excretion.

While the circulatory system serves the same fundamental function across organisms, its structure varies depending on the complexity of the animal. This concludes the explanation of open circulation in some invertebrates like grasshoppers, emphasizing the flow of hemolymph through the tubular heart, aorta, and hemocoel.