Nerocila depressa
| 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 | |
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]
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]
References
- 1 2 3 4 5 6 7 Printrakoon, Cheewarat; Purivirojkul, Watchariya (2011-02-01). "Prevalence of Nerocila depressa (Isopoda, Cymothoidae) on Sardinella albella from a Thai estuary". Journal of Sea Research. 65 (2): 322–326. Bibcode:2011JSR....65..322P. doi:10.1016/j.seares.2010.11.003. ISSN 1385-1101.
- 1 2 3 4 5 SAHOO, AMIYA; Bhakta, D.; Meena, D. K.; Sadhukhan, D.; Das, T.; Kamble, S. P.; Majhi, D.; Samanta, S.; Das, Basanta K. (2021-06-03), Isopod Parasite, Nerocila Depressa (Edwards, 1840) Infestation in Thryssa Stenosoma (Wongratana, 1983) as New Host, and First Record from Narmada Estuary, West Coast of India, doi:10.21203/rs.3.rs-566240/v1, retrieved 2026-04-26
- 1 2 3 Seth, J. K. (2020). "Extension of host range for Anilocra dimidiata, Nerocila sigani and first record of Nerocila depressa (Isopod: Cymothiod) from Odisha coast, India". Indian Journal of Geo Marine Sciences. 49 (8): 1498–1500 – via ResearchGate.
- 1 2 3 Balakrishnan, Srinivasan (2019). "New host records for Nerocila depressa Milne Edwards, 1840 (Crustacea, Isopoda, Cymothoidae) from Digha coast, Bay of Bengal, India". Indian Journal of Geo Marine Sciences. 49 (4): 698–702 – via ResearchGate.
- 1 2 3 4 Anand Kumar, A.; Rameshkumar, G.; Ravichandran, S.; Nagarajan, R.; Prabakaran, K.; Ramesh, M. (2017-03-01). "Distribution of isopod parasites in commercially important marine fishes of the Miri coast, East Malaysia". Journal of Parasitic Diseases. 41 (1): 55–61. doi:10.1007/s12639-016-0749-6. ISSN 0975-0703. PMC 5339172. PMID 28316388.
- 1 2 Ghani, Naseem (2003). "ISOPOD PARASITES OF MARINE FISHES OF PAKISTAN" (PDF). Proc. Pakistan Congr. Zool. 23: 217–221.
- 1 2 3 Rameshkumar, Ganapathy (2013-09-28). "Invasion of parasitic isopods in marine fishes" (PDF). Journal of Coastal Life Medicine. 1 (2): 88–94. doi:10.12980/JCLM.1.2013B1340 (inactive 4 May 2026) – via ResearchGate.
{{cite journal}}: CS1 maint: DOI inactive as of May 2026 (link) - 1 2 3 Rameshkumar, Ganapathy (2013-08-28). "Histopathological changes in the skins and gills of some marine fishes due to parasitic isopod infestation" (PDF). Journal of Coastal Life Medicine. 1 (1): 74–80. doi:10.12980/JCLM.1.20133D233 (inactive 4 May 2026) – via ResearchGate.
{{cite journal}}: CS1 maint: DOI inactive as of May 2026 (link) - 1 2 3 Trilles, Jean-Paul; Rameshkumar, Ganapathy; Ravichandran, Samuthirapandian (2013-03-01). "Nerocila species (Crustacea, Isopoda, Cymothoidae) from Indian marine fishes". Parasitology Research. 112 (3): 1273–1286. doi:10.1007/s00436-012-3263-5. ISSN 1432-1955. PMC 3580147. PMID 23324945.
- ↑ Seth, Jaya Kishor; Mohapatra, Sandeep Kumar; Mohanty, Swarup Ranjan; Behera, Rajesh Kumar; Mohapatra, Anil (2021-12-01). "Confirmation on the occurrence of Cymothoa indica, and first record of Norileca indica, with a note on new host records of Nerocila arres, and Nerocila depressa (Isopoda: Cymothoidae) from Odisha coast, India". Journal of Parasitic Diseases. 45 (4): 944–951. doi:10.1007/s12639-021-01382-1. ISSN 0975-0703. PMC 8556475. PMID 34789976.
- ↑ Bruce, Niel L. (1988). "NEW RECORDS OF FISH PARASITIC MARINE ISOPOD CRUSTACEANS (CYMOTHOIDAE, SUBFAMILY ANILOCRINAE) FROM THE INDO-WEST PACIFIC" (PDF). Proc. Biol. Soc. Wash. 101 (3): 585–602 – via NHM.
- ↑ "WoRMS - World Register of Marine Species - Nerocila depressa H. Milne Edwards, 1840". www.marinespecies.org. Retrieved 2026-04-27.
- 1 2 Aneesh, Panakkool-Thamban; Sudha, Kappalli; Arshad, Keethadath; Anilkumar, Gopinathan; Trilles, Jean-Paul (2013-03-01). "Seasonal fluctuation of the prevalence of cymothoids representing the genus Nerocila (Crustacea, Isopoda), parasitizing commercially exploited marine fishes from the Malabar Coast, India". Acta Parasitologica. 58 (1): 80–90. Bibcode:2013AcPar..58112.3A. doi:10.2478/s11686-013-0112-3. ISSN 1896-1851. PMID 23377916.