Male Parasitism in Angler Fish
Biology 342 Fall 2006
Mikey Badr and Will Gester
Do you take this man? (Finding a host)
Male anglerfish have huge nostrils, used to track down female specific pheromones in the vast empitiness of the deep. After finding males will bite her with his specialized jaws, and within five minutes there is a complete fusion of the tissues at the area of attachment (Munk 2000), becoming permanently attached parasites. From this point on the male with receive all of his nourishment from the female. He will continue to live and grow with her, becoming larger than his free-swimming brethren, until she dies. In exchange he will provide sperm to his gigantic host, resulting in repeated matings. Some species are monogamous, though some have found to exhibit polyandry, in which a female will host multiple sperm-providing parasites.
To have and to hold. (Attachment)
In order to initiate the fusion, the male first penetrates the female epidermis with two specialized spines, protruding from his snout and lower jaw. A “plug” of female skin may be folded into his mouth, meanwhile the entire dorsal portion of his head becomes flush with her skin and fuses. The exact method by which the dermis of the two fuses is unknown, but it has been shown that there is no sharply defined boundary between the two. Indeed, in the area of attachment there is no epidermis to be found at all. (Munk 2000).
In sickness and in health (Parasitism)
Though it is known that the male receives his nourishment from the female bloodstream, there are currently two models through which this may happen. In the first model the circulatory systems of the two fish actually fuse. This has currently only been demonstrated in one specie. Munk (2000) found that vascularization from both organisms can be found at the zone of attachment, supporting the theory. The other model is that the male fish receives feeds using a placenta-like structure, with no actual merging of the circulatory systems. Evidence for this model has been claimed, but not substantiated. Norman and Green- wood (1975)
After attachment a number of physiological changes occur in the male. His eyes degenerate, as they are no longer useful. His digestive system no longer serves much purpose. His testes grow to occupy a large portion of his abdominal cavity, and will continually produce spermatozoa for the female.