Dimorphism, Parasitism and Sex: Reproductive Strategies among Deepsea Ceratioid Anglerfishes

Abstract

Knowledge of the reproductive biology of the Ceratioidei is reviewed and new and scattered evidence is brought together in an attempt to reevaluate some previously accepted ideas concerning the unique sexual habits of these fishes. Notes on taxonomic content, available material, occurrence of parasitism, gravid females and ripe males and the ability of males to ingest food independently of the female are given for each ceratioid family, after which this information is summarized and discussed. Data are presented to support at least three reproductive strategies utilized by ceratioid anglerfishes: sexually mature males of the Ceratiidae, Linophrynidae and perhaps the Neoceratiidae, are obligatory sexual parasites; those of the Caulophrynidae and the oneirodid genus Leptacanthichthys are probably facultative sexual parasites; and those of the Melanocetidae, Himantolophidae, Gigantactinidae and at least some oneirodid genera, are non-parasitic and perhaps spawn during a nonparasitic, temporary attachment. The four ceratioid families in which sexual parasitism has been previously recorded appear to form a highly specialized, monophyletic group, most likely derived from some oneirodid-like ancestor. If a facultative sexual parasitism exists for some ceratioids, particularly some oneirodid genera, it would form a convenient evolutionary intermediate between those ceratioids with obligatory sexual parasitism and those whose males never become parasitic.