Third-stage larvae emerge from eggs of Contracaecum osculatum (Nematoda, Anisakidae).

In Contracaecum osculatum Rudolphi, 1802 (Nematoda, Anisakidae) the first and the second ecdyses occur inside the egg. Larvae forced out from the eggs by coverslip pressure are surrounded by 2 cuticles, revealing 2 previous ecdyses. It is thus the third-stage larva that emerges from the hatched egg and not the second-stage larva as previously believed. The cuticle of the first-stage larva is thin, smooth, and remains in the egg, whereas the cuticle of the second-stage larva is thick, striated, and, serving as a cover, loosely ensheaths the released larva.