In this article we will discuss about the Macrophagy in Hydra:- 1. Subject Matter of Hydra 2. Feeding in Hydra 3. Process 4. Digestion.
Subject Matter of Hydra:
Hydra is an animal under Phylum Cnidaria. It has no head end. The mouth (which serves also as the anus) is the single opening of the only internal cavity, called the coelenteron. At the oral end the mouth is situated on a cone like structure called the hypostome.
Around the base of the cone is a circle of about six tentacles. On the tentacles stinging cells are concentrated. Stinging cells called cnidae or nematocysts are used for food capture and defence. Nematocysts are unique to the phylum and a diagnostic feature of it.
Feeding in Hydra:
Hydra is carnivorous and feeds mainly on small crustaceans. For capturing the food, they possess some specialised cells.
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The structure and functions of these cells are described below:
Cnidocytes/Cnidoblast cells:
They are located throughout the epidermis of the tentacles and are lodged between or invaginated with epitheliomuscular cells of the epidermis (Fig. 2.37). A cnidocyte is a rounded or an ovoid cell with a basal nucleus.
One end of the cell contains a short, stiff, bristle-like process called a cnidocil (Fig. 2.36 & 2.38). The cnidocil in electron microscope, reveals structural similarity with that of a cilium. It remains exposed to the surface.
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The interior of the cell is filled by a capsule containing a coiled, usually pleated tube. The outwardly directed end of the capsule is covered by an operculum or by lid-like flaps. The base is attached to the lateral extensions of one or more epitheliomuscular cells. Sometimes these cells may be associated with a neuron terminal.
