RESUMEN
The trilobite larvae of C. rotundicauda were tested to determine their colour preference and light sensitivity until their first moulting (25 days post hatching) under laboratory conditions. Maximum congregation size of the trilobite larvae was found in the white zone respectively where (n = 12) followed by yellow (n = 8) and orange (n = 8), which showed the larval preference for lighter zones. Morisita's index calculation showed a clumped/aggregated distribution (yellow, blue, orange and white) and uniform/hyper dispersed distribution (green, red and black) for various colours tested. Trilobite larvae showed least preference for brighter regions while tested in the experiment [black; (n = 4) and red; (n = 5)]. Experiments done to determine the light sensitivity of trilobite larvae showed that the larvae had more preference towards ultraviolet lights. The maximum congregation size of 38.8 and 40.7% of the larvae was encountered under ultraviolet light, when the light sources were kept horizontal and vertical, respectively. Overall, results suggested that the trilobite larvae of C. rotundicauda, preferred light source of shorter wavelengths (UV light) and colours of lighter zone (white, yellow, orange), which might be due to their adaptation to their natural habitat for predator avoidance, prey selection and water quality.
Asunto(s)
Cangrejos Herradura/fisiología , Larva/fisiología , Fotofobia , Animales , Color , Rayos UltravioletaRESUMEN
A new sanguinicolid blood fluke, Parasanguinicola vastispina, is described from sea bass Lates calcarifer cultured in Malaysia. It is distinguished by its massive armature and widely spaced genital pores, the female pore being pre-ovarian. P. vastispina inhabits the branchial arteries, dorsal aorta, mesenteric venules and renal artery of its host. No pathological effect was observed in infected fish.
Asunto(s)
Lubina/parasitología , Trematodos/aislamiento & purificación , Animales , Interacciones Huésped-Parásitos , Malasia , Trematodos/clasificación , Trematodos/fisiologíaRESUMEN
Cruoricola lates are found throughout sea bass (Lates calcarifer), most commonly in the mesenteric blood vessels, kidney, pericardial vessels, and eye. Eggs of C. lates were predominantly found in the gills, ventricle, hepatopancreas, and kidneys, but only develop to miracidia regularly in the gills and heart. Single miracidia escaping appear to cause little damage, but groups induce an inflammatory response and haemorrhage. Endocardial macrophages encapsulate eggs trapped between trabeculae in the heart. The reaction to eggs in the kidneys, hepatopancreas and spleen consists of fibrocytic encapsulation. Infection at the levels observed in this study were insufficient to cause lethal pathological changes, but could result in reduced food conversion ratios or impaired immunological capacity.