Question

Where is cnidoblast found?
A. Epidermis
B. Gastrodermis
C. Mesoglea
D. Both epidermis and gastrodermis

Answer 1

Hint: It is the thin, outermost layer of the skin which is visible to the eye. It works to provide protection to the body.

Complete Answer:
- Cnidoblasts are cells which grow into mature, specialized structures called cnidocytes. Cnidocytes are cells of cnidarians (jellyfishes, sea anemones, corals, hydrae, etc.) that shoot off threadlike, frequently poisonous, tubules to capture prey and ward off enemies.
- Each cnidocyte contains an organelle known as nematocyst, cnidocyst, ptychocyst, or spirocyst. This organelle is composed of a bulb-shaped capsule comprising a coiled hollow tubular structure connected to it.
- When the cnidocyte is immature, it is referred to as cnidoblast or nematoblast. The externally directed side of the cell has a hair-like stimulus called a cnidocil, a mechanic and a chemo-receptor.
- As the mechanism is triggered, the tubular shaft of the cnidocyst is expelled and, in the case of a penetrating nematocyst, the forcibly expelled tubule penetrates the aimed organism.

There are two types of tissue: the epidermis is the outermost layer of the skin which we can see and the gastrodermis which lines the inside of the body.
- These two layers are separated by a non-living layer of elastic, gelatinous base material called mesoglea, which provides structure and elasticity at no metabolic cost.
- Cnidoblast cells are present only in the epidermis. It is a cell in which the nematocyst is formed. In Cnidaria, the capsule appears on the surface of the body and the cnidoblast is formed.

Thus, the correct answer is option A i.e., Epidermis.

Note: Cnidocyte cells are found around the mouth and on the tentacles and help to catch or repel predators. Cnidocytes have large stinging organelles called nematocysts, usually carrying barbs at the base of a long coiled cord.