Paris japonica has the most base pairs(149 billion compared to humans 3.5 billion).
With 150 billion base pairs of DNA per cell (50 times larger than that of a human haploid genome), Paris japonica may possess the largest known genome of any living organism; the DNA from a single cell stretched out end-to-end would be longer than 300 feet (91 m)
JAUME PELLICER The largest eukaryotic genome of them all? September 2010 1
The diversity of eukaryotic genome sizes has long fascinated, but at the same time puzzled, scientists who have asked how and why such diversity evolved. These are important questions because we know that the total amount of DNA in the nucleus has both biological and ecological consequences that affect the distribution and persistence of biodiversity. There is a staggering diversity of genome sizes (the amount of DNA in the nucleus) in eukaryotes, with available data for over 10 000 species showing that they currently vary c. 57000-fold. The smallest genome so far reported is in the microsporidian Encephalitozoon intestinalis, which parasitizes a range of mammals, including humans (Vivares, 1999). Its genome comprises just 0.0023 pg of DNA, which corresponds to 2.3 Mbp . At the other end of the range, the genome of the marbled lung fish, Protopterus aethiopicus, with c. 130 000 Mbp (1C = 132.83 pg), is one of the largest ever reported. Given that the length of one nucleotide is estimated to be c. 0.34 nm, this diversity translates into lengths of only c. 2 mm of DNA per somatic nucleus in E. intestinalis and c. 88 m in P. aethiopicus, with our own genome (1C = 3 pg) measuring c. 2 m. Such enormous variation and lack of apparent correlation with organismal complexity has long caught the attention of biologists, including Thomas (1971), who coined the phrase ‘the C-value paradox’ (more recently termed ‘the C-value enigma’; Gregory).
Who has the most chromosomes? Adder’s tongue fern (1440). Who has the most bones? Pythons (in excess of 600). Most cone cells in eye? Mantis shrimp (16).