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Oophagy (// oh-OFF-ə-jee) sometimes ovophagy, literally "egg eating", is the practice of embryos feeding on eggs produced by the ovary while still inside the mother's uterus. The word oophagy is formed from the classical Greek ᾠόν (ōion, egg) and classical Greek φᾱγεῖν (phāgein, to eat). In contrast, adelphophagy is the cannibalism of a multi-celled embryo.
Oophagy is thought to occur in all sharks in the order Lamniformes and has been recorded in the bigeye thresher (Alopias superciliosus), the pelagic thresher (A. pelagicus), the shortfin mako (Isurus oxyrinchus) and the porbeagle (Lamna nasus) among others. It also occurs in the tawny nurse shark (Nebrius ferrugineus), and in the family Pseudotriakidae.
This practice may lead to larger embryos or prepare it for a predatory lifestyle.
There are variations in the extent of oophagy among the different shark species. The grey nurse shark (Carcharias taurus) practices intrauterine cannibalism, the first developed embryo consuming both additional eggs and any other developing embryos. Slender smooth-hounds (Gollum attenuatus), form egg capsules which contain 30-80 ova within which only one ovum develops while all other ova are ingested and packed to an external yolk sac. The embryo then develops normally without ingesting further eggs.
Oophagy is also used to refer to more general egg-eating behaviours such as those practised by some snakes. Similarly, the term can be used to describe the destruction of non-queen eggs in nests of certain social wasps such as seen in Polistes biglumis and Polistes humilis. Oophagy has been observed in Leptothorax acervorum and Parachartergus fraternus, where oophagy is practiced to increase energy circulation and consume more protein. Polistes fuscatus use oophagy as a method to establish a dominance hierarchy; dominant females will eat the eggs of subordinate females such that they no longer produce eggs, possibly due to the unnecessary expending of energy and resources.