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PLATYPUS.
Term Paper ID:25052
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Essay Subject:
Mating, grooming, sleep & dreams, electrodetection, burrows, feeding, incubation, more.... More...
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9 Pages / 2025 Words
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Paper Abstract:
Mating, grooming, sleep & dreams, electrodetection, burrows, feeding, incubation, more.
Paper Introduction:
The platypus spends a great deal of time - “most of [its] life,” according to Gould (1985, 14) - in the water, swimming, playing, and, principally, foraging for food. Adults can spend up to 12 or 14 hours continuously feeding, especially during breeding seasons (Fleay, 1944). During winter, their diets consist of various fly larvae, horsehair worms, and freshwater shrimp; in summer, shrimp and worms are replaced by still other types of fly larvae (Grant, 1989). The enormous amounts of food consumed by adult platypus have been a source of encumbrance in maintaining them in captivity: Fleay’s Jill, weighing 2 lbs herself, was observed to consume 1.75 lbs of food in a single day (1944).
The platypus temperament presents a challenge to researchers hoping to study their habits. Platypus do not easily survive captu
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Another evolutionary feature that aids platypus survival in itsenvironment is the high oxygen-carrying capacity of its blood (Grant,1989). In any event, the bill is clearly an importantsource of sensory information. Platypus blood, made up of 5 % red blood cells asopposed to 45% in humans, displays a greater affinity for oxygen, so thatits physiological needs can be met with smaller amounts of oxygen. Even when the baby ventured out into the water at 17weeks, it consumed little food on its own, implying that the mother wasstill assuming responsibility for its nutrition. In M.L. This solicitude on the part of the mother is explained by the factthat baby platypuses are hatched in a state of extreme helplessness. While Fleay's Jill provided an exception, most platypuses appear to beextremely antisocial animals. The platypus spends a great deal of time - "most of [its] life,"according to Gould (1985, 14) - in the water, swimming, playing, and,principally, foraging for food. Mosman: The Royal Zoological Society of New SouthWales. But in newborn humans, just as in the platypus, the forebrain does not appear to be active during REM sleep. Washington, D.C.: Smithsonian Institution Press. The "sixth sense" sought by researchers toexplain the mystery turned out to be sensitivity to weak electric fieldsproduced by platypus prey, detectable at such low levels as that made by ashrimp flicking its tail (Gregory, 1991). The observation that burrows arepredominantly located above river flood-levels, however, indicate thatplugs are introduced for the "the purpose of providing conditions necessaryfor incubation" (Burrell, 1927, 172). There is little evidence to suggest eventhat individual platypuses show any kind of emotional interest in otherplatypuses, except when a mother is nursing her young. Both male and female platypuses are born with rudimentary "spurs" ontheir hind ankles, which remain and develop to maturity only in males.These spurs are sharp and secrete a venomous substance; wild platypuseshave been picked up with signs of spur wounds, but spurs are thought to beprimarily reserved for use during the mating season. 298. Platypuses are not known to make much noise, except when angered. Natural History, pp. Augee (Ed.), Platypus andechidnas (pp.1 6-114). Based on these findings, researchers suspect that REM sleep may servea more basic physiological function than dreaming or learning, at least insome organisms (Travis, 1997). Because the platypus spends so much of its time burrowed away, oftenin plugged-up cavities far from the nearest source of fresh air, it isexposed to hypoxic conditions. 3 -38. REM sleep is characterized byrapid eye movement and an active brain, and has been associated withdreaming and memory consolidation, as well as learning. Theymay spend as many as eleven weeks in total blindness (Fleay, 1944), anddepend on mothers for food for as long as four months (Grant, 1989). The platypus. Platypusestend to be antisocial even among themselves: rarely do two or more animalsshare a burrow, except when a mother is nursing her young, and never have amale and a female been observed to share a burrow (Burrell, 1927). The highincidence of lone juveniles wandering helplessly at great distances fromrivers supports this conclusion. Because the other monotremes, the echidnas, had not been found toundergo REM sleep, it had been assumed that REM sleep is a trait exclusiveto the "higher mammals," and evolved after monotremes diverged from theother mammalian branches (Travis, 1997). To be a platypus. (1992). Since the venom glandenlarges coincidentally with the testes, during mating season, and maleshave been observed to rush at each other during this time as well,researchers believe that spurs are used in competition for breeding females(Grant, 1989). (1927). According to Grant (1989), thetemperatures inside a burrow range from the winter minimum of 14 degreesCelsius to a summer maximum of 18 degrees Celsius. That is, its environment is frequently onewith higher levels of carbon dioxide and lower levels of oxygen than thosefound in normal air. Innature, they are difficult to observe due to their secretive habits andwhat has been called "shyness" (Burrell, 1927). When not diving underwaterfor food, platypuses are hidden away in earthen burrows dug into riverbanks, and venture out mostly at night, or at dawn and dusk. Ithas been suggested that the plugs, as well as the elaborate structure,serve as safety devices against flood. Natural History, pp. (1998, March). 1 -15. "The eyes would twitch, and the head and bill would make movements similar to what the animal would do when swimming," says Siegel. I have frequently noticed that sickly and enfeebled animals will attempt to perform the toilet motions, but are so little able to correlate their activities that the claws pass helplessly up and down without touching the body at all (Burrell, 1927, 162). [W]hen Siegel and his colleagues at the University of Queensland in Brisbane monitored the eye movements, muscle activity, heart rate, and brain waves of four platypuses, they found that the animals displayed most of the characteristics of REM sleep. Collins, L.R. Gregory, E. The puzzle was compounded by the observation that theplatypus keeps its eyes, ears, and nostrils completely shut underwater,which strikes out the three senses of sight, sound, and smell where thesearch for food is concerned. With the discovery thatplatypuses, an "earlier branch" of mammals, undergo REM sleep, as do birds,the trait may date from as early as 25 million years ago, back to the lastliving common ancestor of birds and mammals (Travis, 1997). Gould, S.J. Causes of unhappiness might includedisturbance by a human, especially in its burrows or while it is groomingon the riverbank. The dramatic increase in this type of interaction during October 199 coincided with [instances]...of mating..." (Hawkins & Fanning, 1992, 1 8) If impregnation is successful, incubation of the eggs is left entirelyup to the female; in any event, the male does not appear to show anyinterest in the young or in the female after copulation (Burrell, 1927). The first is a "short, simpleconstruction in the river bank, just above water level and often under atangle of tree roots" (Strahan, 1995, 38), while the second is much morecomplex, extending up to 2 meters and plugged up at numerous intervals. Extremely young platypuses have been foundwandering wearily far from the ideal habitat of the river bank, and thereis data to suggest that juveniles either die or leave the breeding area atmuch higher rates than do adults (Grant, 1989). The animal makes two different types of burrows, one for normal useand one for nursing newly hatched young. During [September, October, and November] the male seemed actively to seek the female when they were present in the exhibit together and attempted tail-bite interactions (where he grasped the tip of the female's tail with his bill). The enormous amounts of foodconsumed by adult platypus have been a source of encumbrance in maintainingthem in captivity: Fleay's Jill, weighing 2 lbs herself, was observed toconsume 1.75 lbs of food in a single day (1944). Males and females do not interact frequently, except immediatelybefore, during, and after mating. Travis, J. "It's almost a metaphysical question" (Discover, 1998, 26). 23-24. Platypus do not easily survive capture, often dying ofshock and stress, or refusing to eat (Hopson, 1981; Burrell, 1927). (1973). "So if you can tell me whether the baby is dreaming, I can tell you whether the platypus is dreaming," he says. Although platypuses are generally solitary, shy creatures, captivityhas been known to modify these characteristics in some individuals. Inthat case, it makes a "querulous growl, exactly like that of an annoyedbroody hen" (Fleay, 1944, 18). Hoffman, E. Adults can spend up to 12 or 14 hourscontinuously feeding, especially during breeding seasons (Fleay, 1944).During winter, their diets consist of various fly larvae, horsehair worms,and freshwater shrimp; in summer, shrimp and worms are replaced by stillother types of fly larvae (Grant, 1989). He also found that although the forebrain in platypuses was apparently inactive during sleep, their brain stem - a part of the brain not thought to be involved in REM sleep - was active (Discover, 1998, 26). Whenlactating, Jill (Fleay, 1944) was observed to consume an amount of foodnearly equal to her body weight, before returning to the nest to feed herfive week-old baby. The mammals of Australia. Strahan, R. Protecting her eggs and young from outsiders may be another importantmotivation for the mother platypus' introduction of complex passages andplugs into the nesting burrow. Griffiths, M. Nevertheless, the platypus has one feature in particular that ishighly evolved, its electroreceptive bill. Tuned-in, turned-on platypus: as it turnsover on Australian stream bottoms, the animal gets all charged up aboutfood. Other pores,which exhibit lower levels of electrosensitivity, are more responsive tomechanical stimulation. The importance of grooming hasalso been observed by Burrell: As with most wild animals, the first sign of ill-health is the neglect of toilet, and this neglect in the case of Ornithorhynchus is rapidly followed by death. Lower rates of recapture inadult males compared to adult females may be explained by the relativedifficulty with which males are approached in the wild: "[t]he adult maleplatypus is also more difficult to observe in the wild state than thefemale, for these big 'old men' are far more suspicious and retiring thanthe females" (Fleay, 1944, 23). The young, while born in a state of helplessness that lasts fourmonths or more, is thrust out on its own after that time. 18-22. 84-92. One explanation for the high incidence of juvenile mortality ordispersal may be population pressure. Accordingly, some beetle larvae were proffered to Jill, who reacted eagerly by clinging to the fingers that approached her and levering them apart with her bill (Fleay, 1944, 24). (1989). What do platypuses dream of? Recent research has revealed that the platypus engages in up to eighthours of REM sleep per day (Travis, 1997). (1944). The platypus attaches great importance to its grooming,which consists of combing the moisture out of its fur; entering the burrowwith wet fur causes misery and in some cases even pneumonia (Burrell,1927). Mothers are extremely sensitive to intrusioninto the nesting chamber, and "[d]uring many years of observation no malehas been found in a breeding-burrow" (Burrell, 1927, 181). Hawkins, M., & Fanning, D. Discover, pp. (1997, November). They spend a great deal of time hidden awayin burrows, and avoid interaction with each other to the extent of livingalone in most cases. Yet, based ontheir limited cognitive functions and limited life experience, it isunlikely that they are engaging in dreaming or memory consolidation. Having been raised from an early age by humans,she was so tame as to communicate with humans regarding her wants. Since the platypus is not subject toserious predation threat in its habitat, and tends to be long-lived, thepotential arises for population explosion. Some types of pores on the bill are more sensitive toelectric fields than others, particularly those with special nerve endingsassociated with mucus-secreting glands (Griffiths, 1988). Jill, Fleay'splatypus, was ordinarily friendly and comfortable around humans, but whenher nest was invaded by outsiders, she exhibited clear signs of distress. Studies show that the region of the platypusbrain corresponding to the bill is several times larger than thosereceiving input from the eyes and ears (Grant, 89). (1988, May). ScienceNews, p. Furthermore, in all mammal species including humans, newbornsexperience the highest amounts of REM sleep (Discover, 1998). Courtship and mating behavior ofcaptive platypuses at Taronga Zoo. We breed the platypus. Young platypuses, still relatively helpless and inactive, willinstinctively perform the act of scratching their flanks with their hindfeet, often ineffectively (Fleay, 1944). Paradoxes of the platypus.International Wildlife, pp. everyday, and foraged for food in her swimming tankwhile the audience watched. (1995). The platypus: a unique mammal. The question of why platypuses spend so much time in their burrowsremains unanswered. Kensington: New SouthWales University Press. The platypus temperament presents a challenge to researchers hoping tostudy their habits. Engaging in REM sleep is not believed to beassociated with dreaming or memory consolidation in the platypus, and itsuncommunicative nature provides neither opportunity nor reason to concludethat the platypus is "intelligent." References Burrell, H. (1985, August). How the platypus managed to feedits extraordinary appetite in the dark, in often muddy waters, has alwaysbeen a mystery. Sydney: Angus & Robertson Limited. Humidity is a necessary component ofthe nesting environment, as a mere few minutes of exposure to dry air hasbeen known to cause denting in the fragile eggs (Burrell, 1927). Fleay, D. Infact, there is no evidence to indicate that the platypus experiencesanything that may be termed "affection" for its mate, outside the physicalact of mating. Scientific American, pp. The range for air is -12to 34 degrees Celsius, and the range in water is 5 to 24 degrees Celsius.Thus, the burrow provides a less extreme environment. The considerable independenceexhibited by all platypuses may also be instrumental, since each platypusprefers to fend for itself, rather than assemble in large groups that mighttax the resources of a given habitat. Researchers captureplatypuses, mark them, and release them back into the wild; data showsignificantly higher levels of recapture of the same individuals in adultsthan in young, particularly females. Hawkins and Fanning (1992) observed thatthe male and female platypuses at the Taronga Zoo tended to avoid eachother throughout the year, especially during the months of June and July.In fact, minutes after the arrival of the male platypus into the sharedswimming tank, the female would usually leave the tank and return to herburrow. (1991, May). One possibility may be the relatively constanttemperatures maintained within burrows on a seasonal basis, compared withthose in the air and in the water. (199 , January-February). Those that survive into adulthood prove well adapted to theirenvironment, and can live remarkably long lives. Monotremes and marsupials: a reference forzoological institutions. This she does by waving her beak jerkily above the water surface, and repeatedly emerging from underwater dives in the corner nearest the hand holding the food. Melbourne: Robertson &Mullens. Thus, the fact thatthe platypus experience six times more REM sleep than do humans, whoexperience around an hour per day, raises questions regarding intelligenceand dreaming. She voluntarily lefther burrow at 3:3 p.m. In typical REM sleep [that of adult humans], neurons in the forebrain fire just as if the brain were awake. To our delight - and horror - there bulged out and was pushed out, as Jill in her rage turned her back, and began to eject nesting material and earth to block out the daylight, a blind, fat, wrinkled babe...Evidently,...she was in a considerable turmoil over the event, for an hour after we had replaced the youngster in the burrow at midday, Jill appeared in the water in obvious agitation (Fleay, 1944, 35). Platypus dreams. ...Jill slipped forth from her tunnels and began begging for special items of food. Males and females do not form lasting relationships,but separate soon after mating. Fleay'sJill was on display before large groups of humans on a daily basis, andseemed to tolerate, even enjoy, their presence (1944). There was a shrill, sustained growl of annoyance, and Jill's beak and head poked out. The platypus. When he succeeded, the female attempted to escape by spiralling, diving through the logs, or by leaving the tank. Population pressure is relieved by factorslike juvenile mortality and dispersal. Chatswood: Reed Books. No bird or reptile, nor any other mammal, is known to have thiselectrodetection ability (Gregory, 1991), which is centered in theplatypus' bill. After the fourth or fifth month, the young platypus ceases to lactateand depend on its mother for food, and does not even share a daytime nestwith its mother (Fleay, 1944). Grant, T. However, there is littlereason to think that the platypus is "intelligent" beyond its sophisticatedadaptation to its environment. Thick nerves, totaling nearly a million individual nerve fibers, run from the bill to the brain...For comparison, a human finger tip contains about 1, nerve fibers; the entire skin of a hand has fewer than 2 , fibers (Gregory, 1991, 33).
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