Catfish story

There are many stories about one terrible catfish. A toothless, scaleless, merciless catfish capable of the abominable. It is said that this catfish can climb trough the human urethra to feed its insatiable thirst for blood. A fish so terrible that George Myers named a relative of it Urinophilus diabolicus (Myers 1927), in reference to its association to the devil and its scary abilities. Of course, I am not talking about the wels catfish. That is another story.

Two fishermen were reported to reel one enormous catfish in Italy last week (CNN report). Dino and Dario Ferrari. Both Italian. Both boosting youth and energy, and the finest fishing equipment (wink). So what do we know about this catfish? The fish in question is a beautiful specimen of Silurus glanis Linnaeus 1758. This catfish was described by the father of nomenclature himself, more than one hundred years before Johann Strauss II composed the famous melody associated to weddings in many countries around the world. The wels catfish is native to the Danube River and was introduced in reservoirs of Italy and Spain in the 1980s where it has established healthy populations, based on the reports of large size specimens caught in the region. The catfish in question might not be the largest caught, but it is “possibly” the largest reeled. The International Game Fish Association established regulations for fish catches to count as records. For the fish to be a record the fishing has to be done by one person, with no help, and preferably there should be at least one witness that can state that the activity was conducted under such regulations. Just like golf. If I hit a ball into a hazard, take a Mulligan, and then get the ball in the hole with one shot in a par three, I can only say that it could have been a hole in one. But it wasn’t.

The wels catfish is one of 15 species in the genus Silurus, with species inhabiting rivers in Europe and Asia. There is even one species of Silurus in Japan! Like most of its relatives, it doesn’t have scales. Like most of its relatives it doesn’t have teeth like alligators or mammals do. But they do have teeth. Tiny little needle-like teeth, arranged in patches over the premaxillary and dentary bones. Picture this: your upper jaw is made out of two bones that hold teeth. They are attached together in the middle by a suture. These bones are the maxillary (upper jaw) and the dentary (lower jaw). Catfishes have maxilla and premaxilla, whereas the premaxilla is exactly where you expect it to be: anterior to the maxilla. An extra pair of bones, closer to the midline than the maxillary bones, that we don’t have. So now that you can picture the location of the premaxilla on a catfish, think about this bone as a very wide rectangular brush. Like one of those you would use to comb your cat’s fur. The ones with bent needles. That is what catfish teeth look like. This is, actually, a type of teeth not uncommon in fishes. These teeth feel like sand paper to the touch. The coarsest sand paper you’ve ever seen. These teeth are also found in the lower jaw of the catfish, on the dentary, named like the bone that makes up your own lower jaw. The wels catfish is a beautiful gentle giant with a tiny dorsal fin and an extremely long anal fin. Its little beady eyes are probably not the most powerful tools to capture prey, but together with the latero-sensory canals and taste buds that cover its body the job gets done.

The catfish Silurus glanis has been reported to eat pigeons in France. After observing the results of 45 attempts at capturing pigeons, 28% of them were accounted as successful events. Good for the catfish. So, wouldn’t it be a great idea to test the myth and conduct experiment? What about 100 healthy adults shuffling their feet in the waters of the Po River. Or even better! How about 100 adults rolling naked on the bottom of a sandy river in the Amazon basin (that is the requisite, the candiru cannot get through spandex) in the name of science. Volunteers?

If you are interested in this type of stories, there is a fascinating book about the candiru by Steven Spotte (Candiru: Life and  Legend of the Bloodsucking catfishes). I will not spoil it for you.


One ocean sunfish plus one Southern ocean sunfish might equal three

There is a wonderful article by Melissa Hogenboom going around in social media right now. An article about the ocean sunfish, its vertical migrations, and its diet (Weird giant sunfish reveals its secrets). The article describes the results reported in a manuscript by a team led by Itsumi Nakamura of the University of Tokyo, Japan. This manuscript has been accepted for publication in the Journal of Animal Ecology, which is different from a research article that has been published, as the manuscript in question could experience slight changes before its publication.

Melissa’s article is straight forward and accompanied by beautiful photographs, and although it is not a taxonomic paper, it surprised me the name of the study subject was not to be found in the text. I am referring to the binomial name, considering that there are two species of sunfishes that inhabit the coasts of Japan. The ocean sunfish is the common name for Mola mola (Linnaeus, 1758), and Mola ramsayi (Giglioli, 1883) is known as the Southern ocean sunfish (more on the Southern ocean sunfish by the Australian Museum). According to the Catalog of Fishes these are the two valid species names in the genus Mola. The Catalog of Fishes is a public source, updated in a regular basis, that accounts for nomenclature acts (naming) that involve fishes. You can go to the previous link and type “Mola” while selecting species. You will retrieve 54 records. At the end of each species description look for current status. You will quickly notice that not all these names correspond to species in the Family Molidae. Of the 35 species among the members of the family Molidae, many are synonyms of Masturus lanceolatus (Liénard 1840), Mola mola (Linnaeus 1758), Mola ramsayi (Giglioli 1883), Ranzania laevis (Pennant 1776). These species names where proposed between 1776 and the late 1800s and the existence of so many synonyms reflects one thing: there was a lot of confusion about the identity of sunfish species.

Fast forward to the year 2015. Do we know everything that lives on earth? The answer is no. To date we know of at least 32,000 species of fishes. Do we know how many species of the genus Mola can be identified worldwide? A review paper from 2010 (Pope et al. 2010) suggests that there might be at least three different species (more in this great post “Luna, alias “ocean sunfish”. El Pez que más mola”) and points at the work of Yoshita et al. from 2009 on sunfishes from the coasts of Japan, where the morphological differences between Mola ramsayi and Mola mola were stated: Mola ramsayi posses large head bumps (something that we might refer to as a “nose”) vs. a smooth slope on M. mola, deeper bodies compared to M. mola, 14-17 ossicles in the clavus vs. 10-13 ossicles in M. mola (which we would not be able to see unless we have x-ray vision or dissect the fish), and a posterior border of the clavus without a wavy edge vs. a clavus with a wavy edge on M. mola.

Unfortunately, the whereabouts of the material used to describe most of the sunfish species is unknown. The holotype is the specimen (the one), the material object, to which an author assigns a name for (nomenclature act). Fortunately, the holotype of Orthragoriscus ramsayi (synonym of Mola ramsayi) is available for study at the Natural History Museum, London (BMNH 1888.11.29.22), so there is a reference for its name. There is also a holotype for Ozodura orsini (synonym of Mola mola) at the Museo di Zoologia, Università di Bologna, Bologna, Italy (MZUB mount on wall). I am interested in knowing what other secrets about these giants will be revealed in the years to come, about their species diversity, evolution, ecology, physiology, and their parasites. Those parasites that birds eat as the magnificent sunfish lies close to the ocean surface (The Blue Planet, BBC). In the meantime I will continue to be awed by the new knowledge gained on the ecology of Mola mola.

References cited:

Giglioli EH (1883) Zoology at the Fisheries Exhibition. II.–Notes on the Vertebrata. Nature (London) v. 28 (no. 718): 313-316.

Liénard E (1840) Description d’une nouvelle espèce du genre mole (Orthagoriscus, Schn.) découverte à l’île Maurice. Revue Zoologique par la Société Cuvierienne (Paris) v. 3: 291-292.

Linnaeus C (1758) Systema Naturae, Ed. X. (Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.) Holmiae. v. 1: i-ii + 1-824.

Pennant T (1776) British zoology. 4th Edition. London. Vol. 3: Class III. Reptiles. Class IV. Fish. Benjamin White, London. v. 3: 1-425, Pls/. 1-73. [Fishes, p. 41-46, 75-409, pls 8-73.]

Pope E. C., Hays GC, Thys TM, Doyle TK, Sims DW, Queiroz N, Hobson VJ, Kubicek L, Houghton JD (2010) The biology and ecology of the ocean sunfish Mola mola: a review of current knowledge and future research perspectives. Reviews in Fish Biology and Fisheries, 19 January 2010, ISSN 0960-3166 (Print) 1573-5184 (Online), DOI 10.1007/s11160-009-9155-9. 

Yoshita Y, Yamanoue Y, Sagara K, Nishibori M, Kuniyoshi H, Umino T, Sakai Y, Hashimoto H, Gushima K (2009) Phylogenetic relationship of two Mola sunfishes (Tetraodontiformes: Molidae) occurring around the coast of Japan, with notes on their geographical distribution and morphological characteristics. Ichthyological Research 56:232–244. doi:10.1007/s10228-008-0089-3

Mola mola (Linnaeus, 1758) or Mola ramsayi (Giglioli, 1883)? Photo credit: