No, all species do not have the same number of chromosomes. The number of chromosomes varies greatly between species.

Here are some examples:

* Humans: 46 chromosomes (23 pairs)

* Fruit flies: 8 chromosomes (4 pairs)

* Dogs: 78 chromosomes (39 pairs)

* Rice: 24 chromosomes (12 pairs)

* Onion: 16 chromosomes (8 pairs)

The number of chromosomes is not directly related to the complexity of an organism. For example, humans have far fewer chromosomes than some plants.