''Lernaeenicus sprattae'' is a species of

copepod Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (living in the water column), some are benthos, benthic (living on the sedimen ...

in the family Pennellidae. It is a parasite of the European sprat (''Sprattus sprattus'') and certain other fish and is sometimes known as the sprat eye-maggot.

Distribution

''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.

Ecology

This copepod has a large number of developmental-stages, some free-living and some parasitic. Two naupliar stages and the first copepodid stage are free-living and are followed by a second copepodid stage where the larva grasps a host fish. This is followed by four

chalimus Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The ...

stages (nymphal stages) where the larvae are parasitic on the host. During the next stage, the adults are free-living and mate, the male dying soon after copulation. The female moults once more before reattaching to a sprat, either on its external surface or by invading the eye; while in the eye, the female transforms into a mature adult with two attached strings of eggs. The earliest naupliar stages take place before the eggs hatch and are released from the strings. Altogether, there are fourteen developmental stages. The life cycle is very similar to that of ''

Lernaeocera branchialis ''Lernaeocera branchialis'', sometimes called cod worm, is a parasite of marine fish, found mainly in the North Atlantic. It is a marine copepod which starts life as a small pelagic crustacean larva. It is among the largest of copepods, ranging ...

'', a parasite of the European flounder (''Pleuronectes flesus''), the

common sole The common sole, Dover sole, or black sole (''Solea solea'') is a species of flatfish in the family Soleidae. It is one of the largest fish in the '' Solea'' genus. It lives on the sandy or muddy seabed of the northern Atlantic and the Mediter ...

(''Solea solea''), and the

lumpsucker The Cyclopteridae are a family of marine fishes, commonly known as lumpsuckers or lumpfish, in the order Scorpaeniformes. They are found in the cold waters of the Arctic Ocean, Arctic, Atlantic Ocean, North Atlantic, and Pacific Ocean, North Paci ...

(''Cyclopterus lumpusbut)'', but the cycle is slower, with each of the developmental stages taking longer.

Pathology

The copepod commonly burrows into the eye of the host, causing damage to the

retina The retina (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional ...

and

cornea The cornea is the transparency (optics), transparent front part of the eyeball which covers the Iris (anatomy), iris, pupil, and Anterior chamber of eyeball, anterior chamber. Along with the anterior chamber and Lens (anatomy), lens, the cornea ...

. The fish's vision is reduced and it may be blinded. Copepods can also attach to the flank of the fish by piercing it with its clawed limbs. The host's immune response causes inflammation of the surrounding tissue and further secures the parasite's hold. The parasite feeds on the host's blood and lysed cells. The loss of nutrients from the copepod feeding on blood and lysed cells is not enough to kill the fish; instead the host usually dies as a result of the copepod's physical attachment. Infected fish were observed to be slower than uninfected fish, likely due to reduced vision and blindness, which make it harder for the infected fish to escape predation. Disruption in blood flow from parasite feeding and physical difficulty moving due to the location of parasite attachment on the body also contribute to a loss of agility in infected fish.

References

External links

* * {{Portal bar, Crustaceans, Marine life Siphonostomatoida Animal parasites of fish Parasitic crustaceans Copepods of the Atlantic Ocean Crustaceans described in 1806