Thursday, 16 August 2018



 Some animals e.g., echinoderms, annelids, sipunculans use coelomic fluid as a supplementary or sole circulatory system. Coelomic fluid are identical to interstitial fluids or some time differ from this fluid, particularly with respect to specific proteins and cells. Coelomic fluids have the role to transports nutrients, and waste products and gases,. It have function in certain invertebrates (annelids) as a hydrostatic skeleton.

 Hemolymph is the circulating fluid of animals with an open circulatory system. Most arthropods, ascidians, and many molluscs have hemolymph.  These animals hve function to a heart pumps hemolymph at low pressures through vessels to tissue spaces and sinuses. Hemolymph  have high volume and the circulation slow. In the process of movement, essential gases, nutrients, and wastes are transported.

Many times, hemolymph has noncirculatory functions. For example, in insects, hemolymph pressure assists in molting of the old cuticle and in inflation of the wings. Some jumping spiders have hydrostatic pressure of the hemolymph that provides a hydraulic mechanism for limb extension.

The coelomic fluid, hemolymph, or blood of most animals contains circulating cells called blood cells or
hemocytes. Some cells contain a respiratory pigment, such as hemoglobin, and are called erythrocytes or red blood cells. These cells are usually present in high numbers to facilitate oxygen transport. Cells that do not contain respiratory pigments have other functions, such as blood clotting.

The number and types of blood cells vary dramatically in different invertebrates. For example, annelid blood contains hemocytes that are phagocytic. The coelomic fluid contains a variety of coelomocytes  such as amoebocytes, eleocytes, lampocytes, linocytes that have the role in phagocytosis, encapsulation, defense responses glycogen storage, , and excretion. Insect hemolymph contains large numbers of various hemocyte types that function in phagocytosis, encapsulation, and clotting.


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