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If you are wondering through the great untouched rainforests of the Amazon basin, you will sometimes come across a clearing devoid of all vegetation save for a few trees. These bare patches are known as devil’s gardens and are said to be the haunt of the fearsome Chuyachaqui (or Chullachaqui), a shape shifting demon which delights in causing misfortune to travelers. Although the Chuyachaqui’s default form is that of a small misshapen man with one hoof and one human foot, the demon can change shape into a person known to the traveler in order to mislead the latter to doom.
Scientists were curious about these small bare patches of forest. After carefully studying the ecosystem, they discovered that a force nearly as diabolical as the Chuyachaqui is responsible. The lemon ant, Myrmelachista schumanni, produces formic acid, a natural herbicide which it methodically injects into the plants in a “devil’s clearing”. The only plants which the ants leaves alone are Duroia hirsuta, “lemon ant trees” which have evolved a mutualistic relationship with the ants. The lemon ants keep the forest free of competing trees and plants, while the lemon ant tree is hollow inside—a perfect natural ant hive and its leaves provide a source of nutrition for the lemon ants (which are a sort of leaf-cutter).
Large colonies of lemon ant trees have been found which are believed to be more than 800 years old—far older than the life of any ant colony or individual tree. It is remarkable to think these ant/tree settlements have been part of the rainforest since before the Mongol conquests.
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).
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.
Since I have already written so many mammal posts I am creating a new blog category for mammals (I will leave out human concerns to concentrate on zoologic overviews of other species, but please remember that technically we too are mammals and all of the posts on this and every website could fall under this category). To make way for the mammals I deleted the “celebrity” topic for good (I had hoped to make fun of our queasy fascination with lackwit celebrities–but other than an one sighting of the disquieting Richard Simmons, I had nothing). Begone vile celebrities! The age of the mammals has dawned.
I already have plenty of posts about goats, pigs, wombats, hyraxes, and bizarre intelligent monotremes with which to populate this category, but to kick the topic off properly I am writing today about the alpha-predator of the Amazon. This mammal is the king of the Mustelidae (also known as the weasel family) and, if you have ever seen a lightning fast stoat hunting a rabbit, or smelled a skunk, or watched a badger drive off a bear, or witnessed a wolverine tear apart a moose, you will know that the weasel family is not joking around. [ed: what? When did you see any of this?] The largest mustelid is a particularly magnificent creature—the giant otter (Pteronura brasiliensis) which lives throughout the Amazon basin and Pantanal. The giant otter is a long animal and males are up to six feet (2 meters in length) and weigh up to 100 pounds (45 kilograms). Much longer males measuring nearly 8 feet in length were once reported but it is believed that extensive hunting may have eradicated all of the really giant giant otters.
Giant otters are tremendously accomplished fishers living largely on cichlids, characins (such as piranha), and catfish, but, as an apex predator they are opportunists who supplement their diet with snakes, crabs, turtles, and caimans. Although the otters are diurnal predators who hunt at daytime using their large acute eyes to find their prey, their hearing is also excellent and they possess extremely sensitive vibrissae (whiskers) to gauge the faintest water current. Like other mustelids, giant otters have fast metabolisms and they eat about 10% of their body weight per day. Their adaptations to aquatic life include webbed feet, ears and nostrils which clamp shut, powerful tails for swimming, and incredibly dense fur. As with their cousins the sea otters, this valuable fur proved to be their undoing. During the nineteenth and early twentieth century they were hunted to the very threshold of extinction by furriers (and by fishermen who regard them as a clever nuisance). Their numbers still remain low today: only 2,000-5,000 giant otters are estimated to live in the wild.
Giant otters form family groups around a mated pair. Older offspring from years past stay with this pair and help out rearing the young cubs before venturing off on their own. They travel widely through the inundated forest during flood seasons and spend the rest of the year based around a fishing camp which they build beside a lake or a choice stretch of river. These camps consist of large multiple entrance home dens built under and around tree roots as well as several secondary locations (along with communal latrine areas). The otters might also alter river beaches to be more to their liking by removing vegetation. The fur of the giant otter is usually brown, red, or fawn and the otter’s bib is marked with cream and white stipples. These are for identification purposes: otters “persiscope” up out of the water to get a better view of each other and to learn whom they are meeting. Giant Otters are also famous for their complicated (and loud) vocalizations.
Although the adult giant otter has no natural predators, young otters must look out for caimans, jaguars, and anacondas. Additionally the giant otters compete for prey with these creatures as well as with river dolphins, large predatory fish, and large turtles. The otters are always on the lookout for dangerous stingrays and electric eels. None of these natural threats, however, are particularly significant compared with the threat from habitat loss, logging, mining, and industrial pollution.
Some of the native humans indigenous to the great river basins believed the otters were river spirits who had, once taught valuable lessons to the first humans. Other native peoples (particularly fishing people) held that the otters were worthless nuisances to be killed or run off whenever sighted. Such sightings however grow increasingly rare as the giant otter, the longest mustelid, vanishes forever away from all but the wildest places in the rainforest.
Some things are easy to write about. For example, the world’s largest catfish was an effortless topic—what a great fish! There is plenty of information about the animal and its giant size makes it instantly fun and interesting (although the specie’s widespread decline does bring a sense of mounting unease). For a wide variety of reasons, other subjects are considerably more difficult to address. Sometimes the information is unavailable or the data is lurid and upsetting. In a poignant incongruity, one of these troubling topics happens to be the world’s smallest catfish, the candiru, which hails from the Amazon basin of Brazil.
The term itself “candiru” can mean either the species Vandellia cirrhosa, or it can refer to several genera of similar small catfishes. There is apparently even a genus “Candiru”. To put it bluntly the candiru is a vampire catfish. It enters the gills of larger fishes and sucks their blood–well actually, it doesn’t suck the blood as such. To quote “fishbase” an online fish resource, “[The candiru] bites mostly at the ventral or dorsal aorta arteries, and the blood is pumped into its gut by the host’s blood pressure. It does not need any special sucking or pumping mechanism to quickly engorge itself with blood, but simply uses its needle-like teeth to make an incision in an artery.” The candiru is small. Vandellia cirrhosa rarely exceeds lengths of 1-2.5 in (2.5-6 cm) with a width of 3.5 mm (although much larger specimens are known).
The junction of the Amazon River and the Rio Negro, (near Manaus, Brazil) is the principal haunting ground of the candiru. The catfish hides in the sand or mud. When prey swims by—either in the day or at night—the candiru uses its tremendous sense of smell and powerful eyesight to hone in on the other fish’s gills for a blood meal. The Candiru has backwards pointing spines behind its gill covers. It can lock itself into a victim’s flesh with these razor sharp rays.
The candiru is not picky about its blood source and this has made it one of the most feared fish in the Amazon. It has been known to enter swimming humans through various orifices or through open wounds. Lurid ethnological reports from as far back as the 19th century detail this fish’s intimate depredations of human hosts.
It is entirely whimsical—even childish—to speculate about whether the catfish is averse to garlic, possesses immortality, has become a hero to preteen girls, speaks with a strong Baltic accent, etc.