[3] Lernaeenicus sprattae is a parasite of the European sprat (Sprattus sprattus) in northwestern Europe and the European pilchard (Sardina pilchardus) in southwestern Europe, the Mediterranean Sea, and the Black Sea.

[3] The earliest naupliar stages take place before the eggs hatch and are released from the strings.

The life cycle is very similar to that of Lernaeocera branchialis,[3] a parasite of the European flounder (Pleuronectes flesus), the common sole (Solea solea), and the lumpsucker (Cyclopterus lumpusbut),[5] but the cycle is slower, with each of the developmental stages taking longer.

[3] The copepod commonly burrows into the eye of the host, causing damage to the retina and cornea.

The host's immune response causes inflammation of the surrounding tissue and further secures the parasite's hold.