Why are there different classes of titans?


There are 4 size classes of titans.

![](https://i.stack.imgur.com/S2HEW.png)

Taken from [Shingeki no Kyoujin
Wiki](http://img4.wikia.nocookie.net/__cb20130527182654/shingekinokyojin/images/thumb/5/56/Maru1369501858577.png/1000px-
Maru1369501858577.png)

Why is this so? Do they get larger when they eat?




**Spoiler alert!**

> The classes are just sizes and nothing more. However, the 60 m class is not
> really a class but is classified as _special_ or _abnormal_ much like Eren
> and Annie. These specials are basically one of a kind titan that have
> different abilities like jumping and running. We see them several times in
> the series.

