Nerocila depressa
Species of crustacean
From Wikipedia, the free encyclopedia
Nerocila depressa are ectoparasitic isopods that attach onto the skin, leaving lesions that can cause problems for their hosts.[1] They are white in appearance with two dark stripes on their sides and are commonly found in coastal waters of the Northern Indian and Pacific oceans.[1][2][3][4][5][6] N. depressa can affect the sales of commercial fish depending on factors like environmental conditions and density of stock.[5][7]
| Nerocila depressa | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Clade: | Pancrustacea |
| Class: | Malacostraca |
| Order: | Isopoda |
| Family: | Cymothoidae |
| Genus: | Nerocila |
| Species: | N. depressa |
| Binomial name | |
| Nerocila depressa H. Milne Edwards, 1840 | |
Impact on host
Nerocila depressa are ectoparasitic isopods of the family Cymothoidae, which is generally parasitic towards fish, feeding on their host fish’s blood and muscle tissue.[1][8][9] They can attach onto the head, body surface, or fins of the host fish using the hooks of their pereopods (walking legs).[1][9] N. depressa can leave skin lesions or small pinholes in the hosts body surface from penetration of these pereopods, which can cause infections in the host.[8] Infections caused by N. depressa on host fish can result in reduced growth, anemia, or even death.[10][8] Behavioral changes have also been observed in fish infected by Nerocila depressa.[3] They parasitize a variety of fish, but Carangidae, Clupeidae, and Engraulididae seem to be the most frequent host families .[9][11]
Appearance
Nerocila depressa’s body is white in appearance, with two dark stripes along the lateral sides of their body, and no visible eyes.[2][3] N. depressa has a segmented body containing 7 segments, whose ends are posteriorly directed, with segments 5-7 being the longest.[4][2] They have 7 pairs of pereopods that gradually get longer towards the posterior part of the body.[2] The biggest specimen of N. depressa known to be found was around 23-27 mm in length.[2]
Distribution
Commonly found in marine and brackish habitats, mostly in coastal areas.[1][12] Nerocila depressa have been found in warm waters of the Northern Indian and Pacific oceans of India, Thailand, Hong Kong, Taiwan, Indonesia, the Gulf of Tonkin, Pakistan, and Malaysia.[1][4][5][6] Infestation rates are generally highest from October to March, when temperatures are extremely high.[13] Fluctuations in distribution could also be due to seasonal environmental changes such as weather, rainfall, and salinity.[13]
Effect on humans
An increase in Nerocila depressa can cause a decline in fish population of estuary fish.[1] Since N. depressa can delay growth and cause infections in fish, these fish are not fit to sell or eat, possibly resulting in economic loss from commercial fish sales.[5][7] Factors which may induce these parasites on commercial fish are environmental conditions, density of stock, quality of stock, food availability, and more.[7]