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Scientific Name: Caligus arii Bassett-Smith, 1898
English Name: Fish Louse, Parasitic Copepod
Local/Bangla Name: Kaligus (কালিগাস)
Zooplankton : Caligus arii

Photo: Александр Цветков (flickr)

Classification:
Kingdom: Animalia
Phylum: Arthropoda
Class: Copepoda
Order: Siphonostomatoida
Family: Caligidae
Description:
The organism exhibits a wide, flat, semi-circular cephalothorax with relatively inconspicuous frontal plates and small frontal and paired eye spots. The fourth segment is petite, while the genital segment widens towards the rear. There’s a two-segmented abdominal section, equivalent in length to the genital segment, with an exceedingly short distal segment and tiny caudal rami bearing lengthy setae that recede into the abdomen.The antennule’s basal segment features distinct pectinate setae, and the basal process of the antenna is minuscule, whereas the third segment is considerably elongated. While the post-antennal process is missing, the post-oral process is elongated and blunt at its tip. Among the maxillule’s setae, one stands out as notably long, and the maxilla sports a well-defined outer flange and an elongated apical claw. The maxilliped is slender with a brief distal segment. The first leg boasts a sizable dorsal seta, and its endopod is rudimentary, oblong, and curved. The exopod’s distal segment showcases substantial claws, with the second and third segments featuring extended accessory processes and short, spine-like setae. In the second leg’s exopod, the initial claw is large and winged, whereas the second and third claws are diminutive. The segments of the endopod exhibit robust spinules. The fourth leg is flat and comprised of four segments, each hosting sturdy, winged claws. Adult females bear prominent egg strings on both sides of the abdomen. The coloration of adult individuals typically manifests as creamy or light yellow, and there is evident sexual dimorphism.
Habitat & Distribution in Bangladesh:
Its free-living larval forms serve as zooplankton feed for the fish.
Environment:
Freshwater, Marine
Comments:
Its free-living larval forms serve as zooplankton feed for the fish.
Main References:

Ahmed ATA, Kabir SMH, Ahmad M, Rahman AKA, Haque EU, Ahmed ZU, Begum ZNT, Hassan MA, Khondker M (eds.) (2008) Encyclopedia of Flora and Fauna of Bangladesh, Vol. 18. Part II. Arthropoda: Crustacea. Asiatic Society of Bangladesh, Dhaka, 226 pp

DNA Barcodes from Bangladesh
GenBank Accession Number:
Other DNA Barcodes & Nucleutide Sequences
Global IUCN conservation status:
Other Information