The union of two gametes of different nature in terms of size, shape and structure is called anisogamy. Gametes that participate in sexual reproduction are called anisogametes. It can be flagellated and motile or non-flagellated and immobile. One is large in size and the other is small in size. Larger gametes are called macrogametes or female gametes and smaller gametes are called microgametes or pungametes. Such as Pandorina, Chlamydomonas, Caulerpa, Ectocarpus, Ulothrix etc.