In Vivo Culture Study of Free-Living Marine Nematodes (Bathylaimus sp., Oncholaimus sp., Oncholaimellus sp.) Inhabiting West Coast Mallipo, Korea

Abstract

The spawning, development, and early life cycle of three species of marine nematodes in Mallipo, Korea, were studied. With regard to Bathylaimus sp., the number of spawned eggs ranged from four to ten, with an average of seven. The mean hatching time was 99.5 h, while body size was 320–400 μm immediately after hatching and 680–800 μm 1 week after hatching. Twenty-eight days after hatching, Bathylaimus sp. had grown to 1900–2200 μm, which is similar to its adult size and female Bathylaimus sp. developed vulva, and male Bathylaimus sp. developed a spicule. The adult body size of Oncholaimus sp., a scavenger, was 3300–3700 μm, and the number of spawned eggs was 4 to 7 (average 5.2). Spawning to hatching took 72–96 h (average 81 h) and the mean hatching rate was 96.1%. The hatched juveniles grew to 1100–1250 μm 4 days after hatching and 2100–2400 μm 15 days after hatching, which was about 65% of the adult body size. The adult body size of Oncholaimellus sp., another scavenger, was 850–1100 μm, and the number of spawned eggs ranged from 2 to 8 (average 5.3). Spawning to hatching took 52–72 h, with an average of 60 h, and the mean hatching rate was 90.5%. The size of the juveniles ranged from 220–300 μm immediately after hatching to 460–550 μm 5 days after hatching, which was about 50% of the adult body size.