"Wheel animals" - On Rotifers.

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The Phylum Rotifera or wheel animals are funny yet cute looking little microorganism.        They are about 200-500 micrometers long and
are generally found in moist soil, still waters or
free flowing waters. They are detritivores and feed
on bacteria, algae and decaying protozoans.

They might be small but don't underestimate them!
They have a well developed digestive system,
reproductive system and even a nervous system
consisting of a brain! Due to this they are considered
 as animals. 

One of their most unique characteristic is the crown of rotating cilia or the 'corona'.


Lets learn a bit more on the digestive system of rotifers!
The digestive system of rotifers consists of many complex organs some of them being the stomach and mouth!
Lets go one by one!
1) Corona - The corona or the crown of the mouth is lined with cilia(hair like structures) as you have seen in the video.(Taken by me:))
The cilia vibrate and create a vortex of water that attracts food in its mouth. This type of feeding is also called 'Filter feeding'. The size of the corona differs from one species to another. Once they have captured enough food they contract to consume it.
2) Mouth - The mouth of rotifers is simply a cylindrical opening allowing food to enter in.
3) Mastax - The mastax is a ciliated tube with muscles and a hardened jaw called the 'trophi' that helps it to chew and grind food as it passes through its esophagus. 

4) Stomach - The digestion and absorption of nutrients occur in the stomach. Rotifers contain 7 salivary glands including 2 gastric salivary gland helping in this process.
5) Intestine - The intestine has the ability to produce urine and feces from the remaining undigested food material received from the stomach.
6) Anus - Through the anus the waste product is excreted out.

Another special character of the rotifer is its foot through which it is able to stand and stabilize itself and attach itself on other objects, also allowing it to rotate.
The foot acts as a support to the toes in rotifers. Each foot contains upto generally 4 toes. The toe has a gland called 'cement gland' (also the pedal gland) that allows the rotifers to produce a sticky substance allowing it to attach itself on other objects. Some species or rotifers lack this unique feature.

Now let's go forwards and learn about the nervous system in rotifers.
The nervous system of rotifers consists of a brain and nerves.
The brain or in complex terms the cerebral ganglion is located right above the mastax. Through this several nerves extend throughout the body. 25% of the roughly 1000 cells belong to the nervous system!
 (Rotifers are 'eutelic', they have a fixed number of cells from birth.)

The eyes of the rotifer are simple eyes with generally only one photoreceptor cell and is a part of the nervous system too. The bristles of corona are touch sensitive.

That is the end of our journey on rotifers! Hope you guys enjoyed! Never stop being curious!

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