last week I gave you a slightly misleading mystery object to identify:

The European Sprat Sprattus sprattus (Linnaeus, 1758) was the obvious object in the image, but I was actually interested in the parasite attached to its eye:

With that trailing pair of egg strings, this delightful ocular assailant bears a similarity to a past mystery object that also parasitises fish.

If you can remember that far back, you may remember that fish parasite was a member of the Copepoda, which is a group within the Crustacea. Most (although not all) copepods that parasitise fish are members of the Siphonostomatoidae and this week’s mystery object is part of that same Order.

For this particular specimen you don’t really need to get too bogged down in the taxonomy to work out what it is, especially if you recognise the host fish. A quick web search for “Sprat eye parasite” will take you straight to the correct species, although if you search for “fish eye parasite” you’ll eventually find it, after trawling through some fascinating information about the body-snatching eye fluke Diplostomum, which alters its host’s behaviour to make it less, and then more likely to be eaten by predators. And who wouldn’t want to take that informational detour?

So as most people figured out, this is charmingly named Sprat Eye-maggot Lernaeenicus sprattae (Sowerby, 1806).

While we’re taking informational detours, I thought you might appreciate the initial species account for this delightful critter:

Sowerby, J. (1806). The British miscellany; or, Coloured figures of new, rare, or little known animal subjects: many not before ascertained to be inhabitants of the British Isles: and chiefly in the possession of the author, James Sowerby. R. Taylor & Co., London, Vol. 1-2 136 pp., 76 plates.

I hope you enjoyed the challenge and that this eyeball sucking miscreant hasn’t left you too traumatised.