Chromosomes are packages of DNA and may contain more or less DNA depending on species. Humans have 23 matched pairs of chromosomes, one set from each parent, making 46 total. Other organisms have more than two copies of each - they have more chromosomes but don’t necessarily have more genes, just more copies of each gene.

So which organism has the most? Among mammals, that prize goes to the red viscacha rat ( viscacha rat ) with 102 chromosomes, with an average of four copies of each DNA packet. The Agrodiaetus Shahrami butterfly ( click here ) has 268 chromosomes, the most of any multicellular animal.

Not all organisms arrange their DNA is such tidy groups as chromosomes. Some single-celled protozoa, like Oxytricha trifallax , have both a micronucleus (with a complete set of DNA in chromosomes, like ours) and a macronucleus that contains many more copies and snippets of genes. The DNA in the macronucleus is organized into smaller packets called nanochromosomes. There can be greater than 15,000 nanochromosomes in Oxytricha trifallax’s macronucleus, each one containing an average of one gene! For more info, check out: chromosomes in creatures

The adder’s tongue fern is generally believed to have the largest number of chromosomes with 1262 compared to human’s 46. However, the number of chromosomes is not a good indicator of complexity. A lot of DNA in bigger genomes, like the ferns, is “junk DNA” and doesn’t actually code for anything useful. Humans on the other hand are more careful with no accumulating junk DNA and therefore have a smaller, more information-dense genome. In fact, the reason that ferns can have so many chromosomes is that they are ancient enough to have accumulated so many chromosomes.