"So, naturalists observe, a flea has smaller fleas that on him prey; and these have smaller still to bite ’em; and so proceed ad infinitum."
- Jonathan Swift

November 10, 2010

November 10 - Holobomolochus confusus

Here’s another ectoparasite of the European flounder, Platichthys flesus (Linnaeus, 1758) (Teleostei: Pleuronectidae). This time, it is Holobomolochus confusus (Stock, 1959) (Copepoda: Bomolochidae). The photo shows an adult female with 2 egg sacs. This specimen was isolated from the fish’s nasal cavity, which is the typical infection site. In comparison with other ectoparasitic copepods of the European flounder, i.e., Acanthochondria cornuta and Lepeophtheirus pectoralis, it is remarkably smaller, occurring less frequently and in lower numbers. This parasite is commonly found infecting the cod, Gadus morhua (Linnaeus, 1758) (Teleostei: Gadidae), and has also been reported from other species of fish.

For details, see the papers below:
1. Cavaleiro, F. I. & Santos, M. J. (2007) Survey of the metazoan ectoparasites of the European flounder Platichthys flesus (Linnaeus, 1758) along the north-central Portuguese coast. Journal of Parasitology 93, 1218-1222.
2. Cavaleiro, F. I. & Santos, M. J. (2009) Seasonality of metazoan ectoparasites in marine European flounder Platichthys flesus (Teleostei: Pleuronectidae). Parasitology 136, 855-865.

Contributed by Francisca I. Cavaleiro & Maria J. Santos, Universidade do Porto, Faculdade de Ciências, Departamento de Biologia, Rua do Campo Alegre, s/n, FC4, 4169-007 Porto, Portugal.


  1. i have recently been finding this exact parasite coming from my nasal passage for the past year. at first it looked like larvae of some sort then over the months it changed the way it looked.Doctors keep telling me there's nothing in the samples i have provided though it just keeps getting worse and worse.I now have one of the parasites to show the doctor and it is about 1/2 a centimeter in length and the same around, with legs and a head. looks just like this sample picture. i am terrified and afraid of it being too late to save my life.

  2. Please see the sign on the side bar:

    "We do not give any medical or veterinary advice. If you think you or your pets have a parasite, please seek the appropriate care you need from your own doctor or veterinarian."

    Also, it cannot possibly be *this* particular parasite - it is a marine crustacean which lives in a nasal passage of flounders - not people. Please consult your medical doctor or general practitioner.