The life of Grasshopper

Arthropod dissection-PAPBio-3rd per

represented by: MOJDE YADOLLAHKHALES

Objectives

learn about the external and internal anatomy of a grasshopper. Focus on the organs, structures, and functions of the respiratory system. Understand the ecological role of the grasshopper.

Grasshopper

Males have a single unpaired plate at the end of abdomen. Female has two pairs of valves (triangle shapes) at end of abdomen used to dig in sand when egg laying.

In very young stage, the grasshopper has no wings. In later stages, wings are visible as small pads at end of thorax.

Taxonomy

Kingdom: Animalia

Phylum: Arthropoda
Class:
Insecta
Order:
Orthoptera
Family:
Acrididae
Genus:
Romalea
Species:
microptera

Evolutionary relationships of grasshopper

Grasshopper dissection

Respiratory system

In grasshopper, the tracheal system consists of 10 pairs of spiracles, located laterally on the body surface. Of these, 2 pairs are thoracic and 8 pairs are abdominal. The spiracles are guarded by fine hairs to keep the foreign particles out and by valves that function to open or close the spiracles as required. The spiracles open into small spaces called the atria that continue as air tubes called the tracheae. The tracheae are fine tubes that have a wall of single layered epithelial cells. The cells secrete spiral circular thickenings around the tube that gives support to the tubes.

Mechanism

The first four pairs of spiracles are involved in inspiration or drawing in of air that is oxygen-rich. This air passes through the trachea and the air sacs to reach the tracheoles.

The ends of the tracheoles are filled with fluid. This end enters into the tissue. The ends of the tracheoles are also devoid of cuticle and therefore the respiratory surface is very thin making the diffusion of oxygen into the cells easy. As respiration occurs in the cell, the products of respiration accumulate in the cell and this forces the fluid in the tracheoles to enter the tissue. The exit of fluid creates low pressure in the tubes and draws in more oxygen to the tissues where it is needed.

The carbon dioxide produced is detected by the chemoreceptors which make the muscles near the spiracles contract. This pushes the air out. The last six pairs of spiracles are involved in expiration of air.

Thus, in grasshopper there is ventilation or circulation of air as the oxygen-rich air is inhaled through the first four spiracles and the carbon dioxide-rich air is exhaled through the remaining six pairs of spiracles.

In grasshopper, therefore, the respiratory system is independent of the circulatory system.

Interesting facts

  • Although they eat many things, they still have preferences.
  • Female digs hole with abdomen.
  • Some grasshoppers spit a brown bitter liquid as a defensive behavior in response to being handled.
  • Before molting, grasshoppers do not eat and become less active. During the molt, they swallow air to build up pressure to split the old cuticle.

Impact on ecosystem

Positive
As herbivores, grasshoppers link plants to the rest of the ecosystem. Frass (droppings) contribute to nutrient turnover by returning nutrients as fertilizer for the plants. They provide food for birds and other predators.

Negative
Sometimes some species of grasshopper occur in very large numbers and cause serious crop damage and loss of plants in pastures.