Table 1.

Statistics of the ORFs for Ocean Virus datasets

Sample		Num	Min	Max	Ave	Num60
Arctic Ocean	Reads	688590	35	370	99	-
	UA-ORF	1015432	30	58	33	0
	A-Pep	359023	30	162	37	13547
Sargasso Sea	Reads	399343	36	282	104	-
	UA-ORF	345411	30	49	33	0
	A-Pep	211922	30	202	34	1813
Coast of British Columbia	Reads	16456	37	254	102
	UA-ORF	426666	30	61	33	1
	A-Pep	300227	30	196	36	3165
Gulf of Mexico	Reads	771849	38	246	95	-
	UA-ORF	467085	30	54	33	0
	A-Pep	204595	30	155	34	2166

Num, Min, Max and Ave represent the total number, the minimum, maximum, and average length of the reads (in nucleotides), unassembled ORFs (UA-ORF, in amino acid residues) and assembled peptides (A-Pep, in amino acid residues), respectively. Num60 represents the total number of unassembled ORFs and assembled peptides of length ≥ 60. We note that MetaORFA only reports assembled peptides of at least 30 aa. So in this statistics we use 30 as the minimum length of unassembled ORFs, just for the comparison purpose. Also there are still many short ORFs that can not be assembled or assembled well for these four datasets, causing the low average length of assembled peptides. This also re ects the difficulties of assembling of these four datasets.