The anatomical regions of rotifers include the head, neck, trunk, and foot. But what exactly is inside of these regions? Despite being nearly the size of an amoeba, rotifers have multiple basic organ systems.
An average rotifer has fewer than 1,000 cells in its body, and these cells have been arranged to give rotifers a digestive system, a nervous system, rudimentary eyes, and other sensory organs. Click each tab to read about the inner working of rotifers.
Rotifer Digestion
Rotifer Nervous System
Rotifer Senses
The digestive system of the rotifer is located mostly in the central area of the rotifer's trunk.
The cilia of the corona are the first step in the digestive process of rotifers. What role do cilia play in digestion? Think about the answer to this question, then click Show Me to see if you are correct.
Cilia push water particles and food particles into the animal's mouth.
After the mouth, there is a tube referred to as the pharynx where the food is chewed up. The next portion of the digestive tract is called the mastax. The mastax has muscular walls that contain the trophi. Trophi are sometimes referred to as the jaws of the Rotifera. The job of the trophi is to grind down a rotifer's food. After the mastax is the esophagus of the rotifer.
What is the function of a rotifer's esophagus? Think about the answer to this question, then click Show Me to see if you are correct.
The esophagus is a tube that transports the chewed up food to the stomach, just like the human esophagus.
The majority of digestion and absorption of the rotifer's food occurs in the stomach. Following the stomach the rotifers have a short intestine that ends in an opening called the cloaca. Through this opening the rotifer can excrete its waste products.
Most of the rotifer's nervous system is located above a rotifer's mastax.
Rotifers also have a rudimentary nervous system. They have a compact brain situated just above the mastax. Nerves start from the brain and stretch out through the animal's body. The quantity of the nerves and their layout vary between species, but it is usually a simple configuration.
Most of the sensory organs are located in and around a rotifer's head. The cilia seen in this image are sensitive to touch.
The rotifers use structures of the nervous system to perceive information about their environment. Rotifers typically possess one or two pairs of short antennae and tiny sensory pits lined by cilia in the head region. In addition to that, the cilia of the rotifer's corona are sensitive to touch.
The rotifers can also have up to five rudimentary eyes. These structures are very simple, sometimes just a single photo-receptor cell, which is a cell that is sensitive to light.
Question
Which organism is more complex--an amoeba or a rotifer?
Question
Which organism is more complex--an amoeba or a rotifer?
