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The Piraiba (Brachyplatystoma filamentosum)

Today features a short post concerning one of the strangest looking groups of catfish—which is truly saying something since the entire order of catfish appears rather odd.  Brachyplatystoma is a genus of catfish from central South America which includes the largest catfish from that continent, Brachyplatystoma filamentosum, the so-called Goliath catfish or Piraiba, which is capable of reaching up to 3.6 metres (12 ft) in length and can weigh up to 200 kg (450 pounds).  The Piraiba is hunted for food and sport both with hooks and with harpoons.  All Brachyplatystoma catfish are swift sleek fish which live by hunting, but whereas the other species mostly hunt fish, the Piraiba has been known to eat primates.  Specimens have been found with monkeys in their digestive system and attacks on humans are darkly rumored (although ichthyologists scoff that the mighty fish only scavenges the remains of such terrestrial animals).

Brachyplatystoma capapretum (photo by Enrico Richter)

The other Brachyplatystoma catfish species are smaller than the giant Brachyplatystoma filamentosum, but they all have the elongated flattened nose which characterizes the genus.  One of these species, B. tigrinum, has especially lovely stripes.  Although an unusual fish, it is caught in sufficient quantities to be available in specialty stores for home aquariums, where its long nose, pretty stripes, and interesting behavior fetch a premium price.

Brachyplatystoma tigrinus (Zebra shovelnose catfish)

Brachyplatystoma tigrinus

Obdurodon--A Miocene Platypus which flourished 15 to 20 million years ago

Ferrebeekeeper has an abiding interest in monotremes including both the poisonous platypus and the enigmatic echidnas (with their advanced frontal cortex).  But sadly that is about it as far as it goes for the extant egg-laying mammals: there are only two living families of monotremes (with a scanty total of five species split between them).  To learn more about these animals one must turn to paleontology.  Unfortunately even in the fossil record, monotremes are extremely rare.

Based on genetic evidence, biologists believe that the first monotremes made their advent in the history of life about 220 million years ago during the Triassic era; however the earliest known fossil monotreme so far discovered was a fossil jaw from the early Cretacious era about 120 million years ago.  The bones belonged to Steropodon galmani, which seems to have been a beaked swimmer about 50 cm (20 inches) long which lived in Australia.  Steropodon was apparently a giant among Cretacious mammals–most of which seem to have been shrew-sized (so as to better avoid attention from their contemporaries, the dinosaurs). Reconstructions of Steropodon all seem to resemble the platypus, and most paleantologists would probably concede that it was a sort of platypus—as apparently were other Mesozoic fossil monotremes such as  Kollikodon and Teinolophos (platypuses and these platypus-like forbears are called the Ornithorhynchida).  During the Cretaceous era, the land which is now Australia was in the South Polar regions of the world (approximately where Antarctica is today).  Although temperatures were much warmer during the Cretaceous, monotremes must still have been able to deal with terrible cold: it is believed that the extremely efficient temperature control and the deep hibernation mechanism which these animals continue to display first evolved during that time.

An artist's reconstruction of Steropodon

The only monotreme fossil which was not found in Australia was from another platypus-like creature named Monotrematus sudamericanum.  The creature’s remains were found in a Patagonian rock formation from the Paleocene era (the era just after the fall of the dinosaurs). Monotremes probably flourished across South America and Antarctica, as well as on Australia, but evidence is still scarce. There are most likely many interesting monotreme fossils throughout Antarctica, but, for some reason, paleontologists have not yet discovered them. Additionally, unlike the marsupials (which still quietly flourish throughout South America), the poor monotremes were wiped out on that continent.

Another artist's vision of Steropodon galmani--Notice how peeved the poor creature looks!

Last week I wrote about the Eocene era and the great proliferation of mammalian types which took place during that warm and fecund time.  Although most families of mammals alive today first appeared on the scene during the Eocene, obviously the monotremes were already incredibly ancient.  The Eocene does however seem to have been significant time for the monotreme order: the aquatic platypuses were apparently the ancestral monotremes, and echidnas (the Tachyglossidae) probably split off from them during the Eocene.  Unfortunately we have no Eocene monotreme fossils so this conclusion is based on genetic evidence and on the suffusion of Miocene monotremes which include representatives of both Ornithorhynchida and  Tachyglossidae.  Some of these latter creatures are spectacular, like Zaglossus hacketti the giant echidna from the Pleistocene which was about the size of a ram! As Australia dried up so did the monotremes and now there is only one species of platypus left…

The Giant Echidna (Zaglossus hacketti) which lived until 20,000 years ago...

Well, that’s a cursory history of the monotremes based on what we know.  I wish I could tell you more but unfortunately there is no fossil evidence concerning the first half of the order.  Sometimes I like to imagine the first monotremes—which were probably clunky, furry platypus-looking characters with an extra hint of iguana thrown in. These creatures fished in the alien rivers of the Triassic world in a time when dinosaurs and pterosaurs were also still evolving.

Armoured Catfish (photo by Elaine Dockery)

There are about 40 known families of catfishes–give or take a few extinct families and a few mystery species (which will probably be classified as their own families in time).  The largest family of catfish in terms of diversity is the Loricariidae family—the exquisite armoured catfishes of Central and South America.  Nearly seven hundred species are known, and more are being added all of the time.  The extraordinarily successful family is characterized by suckermouths for closely grazing on vegetation and detritus.  They have long slender tapering forms with heavy bony plates around the head and body.  The Locariidae frequently have exquisite fanlike dorsal fins which they can open for display (the dorsal fin is the top fin, which you can see extended in some of the “out-of-the water pictures in the gallery below).  In Fishes of the World Joseph S. Nelson describes additional armament carried by this family, “When present, the adipose fin usually has a sharp spine at the forward edge.” Because of the vagaries of the Amazon and the other tropical rivers they inhabit, Locariidae are adept at breathing air and can survive for more than a day out of the water.

Adult Male Armoured Catfish of Baryancistrus genus (photo by Brian Glover) note the omega-shaped pupil

In addition to their maxillary barbells, which are loaded with sensory organs, the Locariddae are completely covered with taste buds.  The fish are therefore extraordinarily attuned to changes in their environment.  Even their fins and tails have tasting sensors.  Pretty much the only part of the fish’s external body not covered with taste buds are their eyes, which are remarkable in their own right.  Locariidae (save for one subfamily) have highly adjustable omega shaped pupils which give them excellent vision in night or day (additionally, to my way of thinking, they further enhance the creatures’ already endearing personality.)  The male catfish are loyal parents.  In most armoured catfish species, fathers will guard the eggs until they hatch–and they will frequently stick around to defend the larval hatchlings after that.

Hypostomus plecostomus

Aquarists will instantly recognize the family for a famous member, Hypostomus plecostomus, which find service as algae eaters in many tropical hobby tanks.  Most specimens of the Loricariidae for sale at aquarium shops are colloquially known as “Plecostomuses”, “plecos”, “suckermouths” or ”algae eaters”.  A glimpse at the list of Locariidae species from the “CATelog” of “Planet Catfish” will reveal why these catchall terms are used.   I have included a random sampling of these fish from images I found at “Planet Catfish” (I  tried hard to correctly cite the photographers and spell the fish names right).  You should visit that site and check out these amazing successful animals in their spell-binding diversity.

Loricaria similima (Johnny Jensen's Photographic Library)

Pseudancistrus barbatus (Photo by Rémy Ksas)

Pterygoplicthys gibbiceps (photo by Mark Sabaj Pérez)

Rhadinoloricaria macromystax (photo by Mark Sabaj Pérez)

Sturisomatichtys leightoni (photo by Paul E. Turley)

Peckoltia compta (photo by Jacob Lihn)

Leporacanthicus triactis (photo by Håvard Støre Andresen)

Lamontichtys stibaros (Johnny Jensen's Photographic Library)

Farlowella amazonum (Johnny Jensen's Photographic Library)

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