Difference Between Cnidocytes and Nematocysts

Cnidocytes vs Nematocysts

Cnidocyte and nematocysts sound far too different, but they are not so. Therefore, understanding the actual meaning of these terms would be of real importance. The facts about these structures are of great interest, and this article explores those to study whether both these are the same or two different types. Therefore, the presented information would only be beneficial for the reader than not.

What is Cnidocyte?

Cnidocytes are also known as nematocytes or cnidoblasts. These are a type of venomous cells uniquely found in the Coelenterates or the members of the Phylum:Cnidaria. It is remarkable that cnidarians can feed on large fishes by means of predation. This astounding ability is because of the presence of cnidocytes or nematocytes. The exact factual reason is the presence of an organelle called nematocyst in each cnidocyte. The structure and other important characteristics about nematocysts are described under the next paragraph. These venomous cells are very important for the coelenterates in defending their colonies as well as in foraging. Their predatory abilities should be highly regarded, mainly because these cnidarians lack an internal skeleton and being mostly sessile. However, cnidocytes are single use cells and cannot be used after one firing. In addition, misfires and self-stinging have to be avoided. Therefore, a regulatory mechanism of firing is present. According to the structure of nematocytes, there are more than 30 types, but they all fall under four main types. They four types have different strategies to attack the prey including piercing, sticking, wrapping, and other methods of firing. Therefore, the importance of cnidocytes for the cnidarians cannot be compared with other organs in the extremely competitive ecosystem.

What is Nematocyst?

Nematocysts are specialized organelles found inside the nematocytes of coelenterates, as it is described above. A nematocyst is a capsule with the shape of a bulb, which contains a sharp-edged barb connected to the bottom of the capsule by a coiled thread. Outside the capsule, there is a small hair-like structure called cnidocil, which is the trigger to fire the barb with the poison. When the trigger is activated, the barb with the poison reaches the target (mostly the skin of an organism or prey) at an ultra-speed with an acceleration of 5 41,000,000 metres per second. The average time to reach the target organism is calculated by recent studies, and it is only 700 nanoseconds. Millions of these nematocysts activated at once by the whole colony of coelenterates (e.g. jellyfish) can easily disable even a large sized prey. When an organism wanders through a colony of cnidarians, the invisible cnidocil triggers are touched, and a sudden poisonous attack is resulted to the death. Usually, the toxin is identified as a neurotoxin, which paralyses the nervous system of the prey animal.


What is the difference between Cnidocytes and Nematocysts?

• Cnidocytes are a special type of cells in cnidarians, whereas nematocysts are specialized sub-cellular organelles found inside cnidocytes.

• Cnidocytes are of four main types, and nematocysts are found in one of those types.