The cells of a bird, a fish, and a lizard are not the same .
Each species of living beings has in all its cells a number of chromosomes that is characteristic of the species.
The group of fish comprises several species. In one of them, the white shark ( Carcharodon carcharias ), the number of chromosomes is 82, grouped in 41 pairs.
The group of birds also includes several species. Taking as an example a species of hummingbird ( Colibri thalassinus ) we can say that it has 114 chromosomes that form 57 pairs.
The lizard Anolis carolinensis has 36 chromosomes that form 18 pairs.
If cells have different numbers of chromosomes, they can never be the same .
On the other hand, even within the same organism, cells have different shapes and functions. This is because, although they have the same genetic make-up, not all genes are expressed in all cells.