Smallest animal genome

The smallest-known genome (i.e., total amount of DNA in the nucleus of a cell) for an animal assessed to date using best-practice methods is 18.8 million base pairs (Mbp, or megabase pairs), for the plant-parasitic nematode Pratylenchus coffeae. These soil-dwelling roundworms can affect the roots of several crops including potatoes, bananas and strawberries. Its genome was calculated for a study published in the journal Nematology in January 2007.

This is around 170 times smaller than the human genome, which contains c. 3.2 billion base pairs (Gbp, or gigabase pairs).

At the other end of the spectrum, the largest-known animal genome is 129.9 Gbp for that of the marbled lungfish (Protopterus aethiopicus) of Africa as documented in the Journal of Experimental Zoology by Dr Keith Thomson in June 1972.

The largest genome for any organism assessed to date using best-practice methods is 160.45 Gbp for the Tmesipteris oblanceolata fork fern, as reported in iScience on 31 May 2024. It is native to tropical forests in the French overseas territory of New Caledonia and other nearby islands in the south-west Pacific Ocean.