Early development of the head skeleton in Brycon moorei(Pisces, Ostariophysi, Characidae)

Authors

  • P. Vandewalle,

    Corresponding author
    1. Université de Liège, Département des Sciences et Gestion de l’Environnement, Laboratoire de Morphologie fonctionnelle et évolutive, Institut de Chimie B6, Sart Tilman, B-4000 Liège, Belgium,
      Tel.: +32 4 366 50 40; fax: +32 4 366 37 15; email: p.vandewalle@ulg.ac.be
    Search for more papers by this author
  • G. Germeau,

    1. Université de Liège, Département des Sciences et Gestion de l’Environnement, Laboratoire de Morphologie fonctionnelle et évolutive, Institut de Chimie B6, Sart Tilman, B-4000 Liège, Belgium,
    Search for more papers by this author
  • P. Besancenet,

    1. Laboratoire d’Ethologie et de Psychologie animale, Centre de Recherche et d’Education en Aquaculture, Chemin de la Justice, B-4500 Tihange, Belgium and
    Search for more papers by this author
  • E. Parmentier,

    1. Université de Liège, Département des Sciences et Gestion de l’Environnement, Laboratoire de Morphologie fonctionnelle et évolutive, Institut de Chimie B6, Sart Tilman, B-4000 Liège, Belgium,
    Search for more papers by this author
  • E. Baras

    1. IRD, UR-175, Avenue J.-F. Breton 361, F-34033 Montpellier, Cedex O1, France
    Search for more papers by this author

Tel.: +32 4 366 50 40; fax: +32 4 366 37 15; email: p.vandewalle@ulg.ac.be

Abstract

At hatching (15 h post fertilization), Brycon moorei possesses no skeletal structure. Thereafter, development is very rapid. The first oral teeth appear no later than 3 h post-hatching, but they remain covered with epithelium until c. 45 h. At 7 h, the trabecular bars and part of the cartilaginous visceral arches are visible and at 15 h, the dentaries and premaxillaries are present. At 25 h, i.e. the onset of piscivory and cannibalism (the yolk sac is only fully resorbed after 36 h), the oral teeth are fully developed, the first pharyngeal teeth are formed, and some head movements already appear synchronized, but the mouth cavity is not completely isolated from the neurocranium by bony structures. Thereafter, no new buccal or pharyngeal bony structure is visible until 45 h, when the maxilla and opercula appear, along with a new type of cannibalistic behaviour. Cartilage resorptions also start at 45 h, but with no concomitant replacement by formation of calcified structures. Later, development gradually becomes similar to that of many previously studied teleosts. The developmental pattern of B. moorei is thus extremely rapid in comparison with other teleosts, i.e. it prioritizes feeding structures that permit the expression of piscivory at a very early age. The uniqueness of this pattern is discussed in relation to ecological constraints on early feeding and fast growth.

Ancillary