Is this a Copepod?

[hillegom]

their numbers will increase or decrease depending on how much food is available to them.

I just picked this up on the net for you, describing them a little better.

The animals you are seeing are small crustaceans most commonly associated with the order Amphipoda, Isopoda and class Copepoda. The copepods, as we will collectively call them here, are quite harmless. They inhabit ocean waters and can be either pelagic (free swimming) or benthic (bottom dwelling). Only a few of the thousands of species known are parasitic. These are tiny animals less than a quarter inch long that feed on organic detritus, microscopic organisms or anything small enough for them to digest. They are an important part of the food chain, being feed upon by higher animals. In our aquariums the copepods are a good indicator of how well our ecosystems are developing. They will bloom in the tank when the temperature is slightly warmer and a food source is available. The name copepod is derived from the Greek words for oar and foot. The name demonstrates the simplicity of the animal. It is commonly composed of a head, thorax, and abdomen. It utilizes pairs of appendages for sensing and movement. Copepods are sometimes confused with small, white dots that grow on live rock and glass but do not move around. These are hard tube worms of the family Serpulidae.