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Thursday, 16 August 2018

What is Transport system in Invertebrates and give types of circulatory systems..?




Transport system in Invertebrates and types of circulatory systems


Transport system is the system in which different material, nutrients, and gases are transport from one part of the body to the other. Invertebrates transport system may be external and internal. We discussed following invertebrates transport system.

Protozoa

 Protozoa are small, with high surface-area-to-volume ratios all they need for gas, nutrient, and waste exchange is simple diffusion. In protozoa, the plasma membrane and cytoplasm are the connecting link through which materials diffuse to various parts of the organism, or between the organism and the environment.
Sponge
Some invertebrates have evolved specific transport systems. For example, sponges circulate water from the external environment through their bodies, instead of circulating an internal fluid.

Cnidarian

Cnidarians in which Hydra, have a fluid-filled internal gastrovascular cavity .This cavity provides nutrients for all body cells that lining the cavity, provides oxygen from the water in the cavity, and is a reservoir for carbon dioxide and other wastes. Simple body movement moves the fluid.
The gastrovascular cavity of flatworms, such as the planarian
Dugesia, is more complex than that of Hydra. In the planarian, branches penetrate to all parts of body.
Branched gastrovascular cavity runs close to all body cells, diffusion distances for nutrients, gases, and wastes are short. When body move than it distribute materials to several parts of the body.
Pseudocoelomate
Pseudocoelomate invertebrates, such as rotifers, gastrotrichs, and nematodes, use the coelomic fluid of their body cavity for transport. These animals are small, and body move against the coelomic fluids, which have direct link with the internal tissues and organs, produce adequate transport. A few other invertebrates e.g., ectoprocts, sipunculans, echinoderms also depend largely on the body cavity as a coelomic transport chamber.
Molluscs
Molluscs have transport functions that occur with a separate circulatory system. A circulatory or cardiovascular system is a specialized system in which a muscular, pumping heart moves the fluid medium called either hemolymph or blood in a specific direction determined by the presence of unidirectional blood vessels.
Types of circulatory system and their role in invertebrates
The animal kingdom has two basic types of circulatory systems: open and closed.

Open circulatory system,

 In an open circulatory system, the heart pumps hemolymph out into the body cavity or at least through parts of the cavity, where the hemolymph bathes the cells, tissues, and organs.

Closed circulatory system

 In a closed circulatory system, blood circulates in the confines of tubular vessels. The coelomic fluid of some invertebrates also has a circulatory role either in concert with, or instead of, the hemolymph or blood.
Role
The annelids, such as the earthworm, have a closed circulatory system in which blood travels through vessels delivering nutrients to cells and removing wastes.
Most molluscs and arthropods have open circulatory systems in which hemolymph directly bathes the cells and tissues rather than being carried only in vessels. For example, an insect’s heart pumps hemolymph through vessels that open into a body.

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