A peculiar behaviour has been documented in one species of cichlid, the rainbow
cichlid Herotilapia multispinosa. Working in the lab of Miles Keenleyside at the
University of Western Ontario, Simon Courtenay exposed parental rainbows to
oxygen concentrations of only 2 ppm. When the eggs hatched, the parents did not
gather the emerging wrigglers into pits dug in gravel as usual. Instead they sucked the
wrigglers into their mouth and spat them into vegetation, onto which the wrigglers
attached themselves thanks to glue-producing glands on their head. Courtenay
showed that this behaviour, called “wriggler-hanging”, was more prevalent when
oxygen concentration was low. Presumably, wrigglers benefited from being close to
vegetation because of the oxygen released by photosynthesis and also because the
plants were often closer to the surface. Wriggler-hanging has also been reported in
other cichlids, such as the angelfish, the red discus, the severum and the festivum.
are low. This prediction is borne out. I have taken a battery-operated oxygen meter
to tide pools where male threespine sticklebacks tended their nests full of eggs, and
have found that lower oxygen levels coincided with higher percentages of time spent
fanning by the fish.26 Dutch ethologists working in the lab have also been able to
coerce male sticklebacks into fanning more by connecting a tube to their nest and
pumping deoxygenated water through it.27 Higher fanning levels caused by low
oxygen represent a great expenditure of energy by parental males, to the point that
they may lose weight and be unable to successfully breed a second time after the first
stressful attempt. This was recently demonstrated in common gobies, Pomatoschistus
microps, by Jackie Jones and John Reynolds from the University of East Anglia
A peculiar behaviour has been documented in one species of cichlid, the rainbowcichlid Herotilapia multispinosa. Working in the lab of Miles Keenleyside at theUniversity of Western Ontario, Simon Courtenay exposed parental rainbows tooxygen concentrations of only 2 ppm. When the eggs hatched, the parents did notgather the emerging wrigglers into pits dug in gravel as usual. Instead they sucked thewrigglers into their mouth and spat them into vegetation, onto which the wrigglersattached themselves thanks to glue-producing glands on their head. Courtenayshowed that this behaviour, called “wriggler-hanging”, was more prevalent whenoxygen concentration was low. Presumably, wrigglers benefited from being close tovegetation because of the oxygen released by photosynthesis and also because theplants were often closer to the surface. Wriggler-hanging has also been reported inother cichlids, such as the angelfish, the red discus, the severum and the festivum.are low. This prediction is borne out. I have taken a battery-operated oxygen meterto tide pools where male threespine sticklebacks tended their nests full of eggs, andhave found that lower oxygen levels coincided with higher percentages of time spentfanning by the fish.26 Dutch ethologists working in the lab have also been able tocoerce male sticklebacks into fanning more by connecting a tube to their nest andpumping deoxygenated water through it.27 Higher fanning levels caused by lowออกซิเจนหมายถึงรายจ่ายที่ดีของพลังงานโดยผู้ปกครองชาย ไปยังจุดที่พวกเขาอาจสูญเสียน้ำหนัก และสามารถสำเร็จขุนเป็นครั้งที่สองหลังจากครั้งแรกพยายามเครียด ล่าสุดนี้ถูกแสดงใน gobies ทั่วไป Pomatoschistusmicrops, Jackie โจนส์และจอห์นเรย์โนลด์สจากมหาวิทยาลัยของอีสต์แองเกลีย
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