Question: how many chromosomes do earthworms have?
Answer: In most lumbricids, the basic haploid set includes 18 chromosomes, and diploid, 36 chromosomes (Viktorov 1993, Vsevolodova-Perel and Bulatova 2008, Bakhtadze et al. 2008, Kashmenskaya and Polyakov 2008). In polyploid members of the family, the number of chromosomes is usually a multiple of 18.