One of the nice thing about diving is that it gives you the privilege to see what most people do not see. The ocean covering 75% of our planet means that there are numerous species that are still unknown to science and behavior of marine life still brings its share of novelties. It is not something that should be of any surprise given how limited can be the time of observation underwater for a human, but still something that we tend to forget.
Doing underwater photography also clearly makes you discover yet another world which are the colors that one cannot see underwater. Typically, white appears bluish at the surface and past 5m red starts to look dark sometimes appearing entirely black. Usage of strobes underwater brings to our eyes a world full of intense colors.
A few weeks ago, I was diving in Anilao in the Philippines with a group of friends, all of us doing underwater photography as a hobby and we were able to observe an extremely rare behavior: a lizardfish attempting to eat a frogfish. While for the casual reader this may sound relatively boring, one has to know that frogfish are particular to underwater photographers as they are a subject of choice due to their particular feature: the first dorsal spine is modified as a fishing lure to attract prey.. and they have unique ‘facial’ characteristics. Moreover, observing predatory behavior underwater is also pretty rare in itself for the reason mentioned earlier.
The particularity about this event was the reaction of the frogfish which self-inflated in a defensive behavior and put the lizardfish with quite a mouthful. While this behavior was known by science, it has apparently never been observed widely nor even photographed. I stayed more than 30min around the lizardfish that did a couple of quick release/catch to try different angles without much success, the frogfish was still alive and ‘breathing’.
In a communication with Theodore W. Pietsch, professor and curator of fishes at the University of Washington (who recently published a paper following the discovery of a new specie of frogfish), he suggested to me that those pictures may well be the first to show this behavior and he was kind enough to quote the portion of his book Frogfishes of the world related to body inflation:
Numerous authors have commented on the ability of frogfishes to expand their stomachs enormously by swallowing large quantities of air or water, an adaptation usually attributed only to the pufferfishes (families Diodontidae and Tetraodontidae), a few filefishes (genus Brachaluteres, family Balistidae; see Clark and Gohar, 1953:46, fig. 12), and swell sharks (genus Cephaloscyllium, family Scyliorhinidae). The capacity to “expand their bellies like a balloon”; was first recognized by Marcgrave (1648:150) and later confirmed by Commerson (ca. 1770; MSS 889, 891), Cuvier (1817b:422), Swainson (1838:202), Valenciennes (1837:389), Gunther (1861:184), and a host of twentieth-century authors including Jordan and Sindo (1902:367), Gregory (1933:388), Gordon (1938:20), Schmitt (in Longley and Hildebrand, 1941:304, 305), Barbour (1942:31), Schmitt and Longley (in Schultz, 1957:52), Bohlke and Chaplin (1968:714, 718), Randall (1968:291), and Halstead (1978:354). In the most significant of these many reports, Gordon (1938:20) wrote that Histrio histrio sometimes “uses the quick gulping technique for self-defense. If it is attacked by a larger fish,. . . [it] throws open its jaws, swallows water as it is on the point of being devoured, and instantly pumps itself up to an unexpected size. Thus the swallower is forced to cough up the swallowee.” In summary, a survey of the literature strongly suggests that body inflation is an often-used defensive response in frogfishes, functioning to ward off potential predators or to defend a feeding or shelter site from intra- and interspecific competitors.
It is true that at least some species of frogfishes (Antennarius striatus, A. hispidus, A. ocellatus, A. radiosus, and Histrio histrio) inflate themselves with air when removed from the water, but initiating this response nearly always takes a considerable amount of poking and manipulation on the part of the experimenter. Furthermore, in all of our 14 years of experience in maintaining living antennariids in laboratory aquaria, often harassing the animals beyond what might be expected under natural circumstances, we have not witnessed a single case of body inflation due to swallowing water. Thus we conclude that reports of frogfishes that have inflated themselves with water-filled stomachs, if not false, describe something that occurs very infrequently in nature and is perhaps an ability confined to H. histrio. We also conclude that observations of inflation by swallowing large quantities of air have all resulted from human removal of frogfishes from their natural medium.
Gunther (1861:184) went further than most by suggesting that body inflation provides a mechanism for dispersal: frogfishes are “enabled, by filling the spacious stomach with air, to sustain themselves on the surface of the water. . . . They are therefore found in the open sea as well as near the coasts, and being bad swimmers, are driven with the currents into which they happen to fall.” Jordan and Sindo (1902:367), in apparent reference to Gunther (1861), added that they are “therefore widely dispersed by the currents of the sea.” Although some antennariids, particularly Histrio histrio, may drift on the surface in an inflated state for short distances, it seems very unlikely that geographic distributions have been altered substantially in this way.
In addition, as confirmed by Rachel Arnold from the University of Washington, this frogfish is also a specie is yet to be described. As it is, it seems to be at this time relatively common to a particular area where we have been diving in Anilao as I have had pictures of about a dozen different one of various patterns and colors such as the grey one on the left. More will be available on Flickr in the next couple of days as I continue to go through all the shots taken during this period.