Approximately how many species are in the order Siphonaptera?

• A. 500
• B. 10000
• C. 1900
• D. 100

Answer: (C)

Fleas, the insects in this order, are specialized, wingless ectoparasites that feed on the blood of mammals and birds. Their global species count is in the low thousands, with current estimates typically around two thousand described species. Saying about 1,900 fits comfortably within that range, reflecting the described diversity across many hosts and regions.

If you see numbers like 500 or 100, that underestimates how many distinct flea species have been identified and described across different genera and host species. A figure as high as 10,000 would be larger than most taxonomic assessments for this group. So, roughly 1,900 is a solid approximate count for the order.