Note: This is Dark_Knight's Web Creature Classes List, not mine. From: http://www.geocities.com/TelevisionCity/Studio/8087/index.html
WEB CREATURE CLASSES
Class-A: Spore only. No offensive or defensive capabilities except the ability to survive all conditions. Once in a suitable environment, will turn into a Class-B.
Class-B: Worm-like. Ravenous, will eat anything; Viruses of all classes, Sprites, Binomes. Once gorged, will turn into a Class-C.
Class-C: A travelling cocoon. Large and tubular, with impenetrable skin. When mature, any one of the classes may emerge (including Classes A and B).
Class-D: Web Probe. No offensive capabilities, but can communicate with all other classes, regardless of distance or location. Took part in the invasion of Mainframe.
Class-E: Web Fighter. Fast, manuverable and deadly, they are lightly armoured and heavily armed. They are also inherently aggressive. Took part in the invasion of Mainframe. Also known as drones.
Class-F: Web Siege Fighter. Slow and not as manuverable, they are still heavily armoured and armed. Took part in the invasion of Mainframe.
Class-G: Whale-like, large and ponderous, they are unarmed but extremely well armoured. The Saucy Mare covers herself in the armour plates of these creatures.
Class-H: These are the Creatures ridden by the Web Riders. They are moderately armoured, and have teeth for weapons. They are aggressive, but will obey orders.
Class-I: These are small squid-like creatures. They are something like hawks in the User world; fierce and deadly, but still can be tamed.
Class-J: Large squid-like creatures. Feeds on tears and other sources of inanimate energy. Benign, unless they suck the power out of your Keytool or something.
Class-K: Large pod. Benign (from a certain point of view). Wanders around, spurting clouds of Web Spores occasionally.
Class-L: Medium-sized crab-like creature. Its flesh is a delicacy among the Web Riders. Will be extremely aggressive if provoked, using its pincers to penetrate almost anything.
Class-M: Portal-forming. Leeches energy from Sprites and Binomes, and steals their code as well. Able to merge with and control Viruses.
Class-N: Tear-forming. Will create tears from anything, anywhere. The larger ones create massive tears that cause disturbances in systems 33.6 baud away.
Class-O: Large and deadly, they are fast, heavily armed, and heavily armoured. If it ever enters a system, it will drain the system's energy, including animate sources. It will then release the energy in a Shock Wave that will annihilate the system.
There may be many more types of Web Creatures, still unknown. Updates will be added when they are discovered.