The system through which blood flows is called circulatory system. The circulatory system of grasshoppers is free-type (grasshoppers, grasshoppers, shrimps, mosquitoes, flies, spiders, snails, oysters, octopuses). The circulatory system in which blood is freed from the heart through the ostia or ducts into the body cavity or sinuses and returns to the heart through the ostia or ducts is called free circulatory system. It consists of four main parts. Hemolymph or blood, hemocele, dorsal vessels and accessory pulsating organs.
1. Hemolymph: Blood of grasshopper is made up of two components. Plasma and hemocytes.
(i) Plasma: Plasma is a colorless liquid. It does not contain hemoglobin. It contains protein, sugar, glycerol, amino acid, glucose, organic acid, ester, sterol, triglyceride, urea, uric acid, nitrogen, sodium, calcium, magnesium, potassium, phosphate, hemoxanthin, trihalose, diglyceride, tyrosine, trihalase etc. Dr. Siddiq Publications
(ii) Haemocytes or Blood Cells: Grasshopper blood contains only white blood cells or Haemocytes (15,000-60,000). It does not contain red blood cells. Haemocytes can be divided into three types. Prohemocyte, transitional hemocyte and giant hemocyte. Prohemocytes 6-9 mµ (23%), transitional hemocytes 9-19 mµ (68%) and giant hemocytes 19-23 mµ (9%).
Hemolymph function
(i) Haemolymph acts as a water reservoir. It contains 92% water.
(ii) It transports nutrients, minerals, hormonal secretions.
(iii) Maintains water balance in the body.
(iv) Wings help in circulation and shedding of shells.
(v) Hemocytes ingest microbes by the process of phagocytosis. As a result, disease is prevented.
(vi) Haemocytes help in blood clotting and wound healing.
(vii) Haemocytes secrete mucopolysaccharides to form connective tissue.
2. Haemocoel: The word haemocoel is formed from the Greek words haema meaning blood and coel meaning cavity. A body cavity filled with hemolymph is called a hemocele. Their hemocele is called myxocele. It is divided into three chambers or sinuses by the dorsal membrane and digital membrane. These are-
(i) Pericardial sinus: It is located above the dorsal membrane. It contains the heart.
(ii) Perivisceral sinus: It is located below the dorsal membrane. The alimentary canal is located in it. Dr. Siddiq Publications
(iii) Perineural sinuses: It is located under the digital membrane. It contains nerve fibers.
3. Dorsal canal: The dorsal canal consists of three parts. These are-
(i) Dorsal aorta: The first chamber of the heart narrows to form a cylindrical part. This is called the dorsal aorta. It extends from the forehead to the head. It does not contain ostia.
(ii) Heart or heart: The heart of the grasshopper is located in the pericardial sinus. It is composed of several funnel-shaped chambers. The first 3 chambers are located in the thorax and the last 10 chambers are located in the abdomen. In the region between the two chambers, the cardiac wall folds from both sides and enters the cardiac cavity. Each fold has a hole. It is called Ostia. Each chamber is connected to the pericardial sinus by ostia. A pore between two adjacent cells is called an intercellular pore.
(iii) Alary muscle: The triangular muscle that is attached to the heart is called Alary muscle. These muscles arise from the digital floor of the targum. Its broad end is attached to the heart. Alary muscles (6 pairs in total) contract and expand the heart.
4. Accessory Vibrating Organs: Antennae, legs and base of wings have accessory organs. Each appendage consists of an ampulla and a duct. They pulsate the hemolymph from the sinuses into the appendages.