Animals in which males take on the role of caregivers henrique_bitencourt / szymon_bzoma / michael_leven - iNaturalist When a video showing a pair of arapaima surrounded by hundreds of babies went viral on social media, many people were impressed by the scene. What few know is that the observed behavior is far from being an exception. In different groups of animals, males can incubate eggs, protect nests, carry offspring and even increase their chances of reproduction precisely because they demonstrate that they are good caregivers. ? Also follow Terra da Gente on Instagram Science calls this behavior parental care. According to a review published in the journal Ecology and Evolution, it encompasses any parental investment that increases the survival, development or quality of offspring, as long as the benefits for the offspring outweigh the costs for the adults. The authors highlight that this type of care emerged independently several times throughout evolution and can be exercised by the mother, the father or both, depending on the species. A review by the Royal Society reinforces that there is no single family model in nature. When comparing different groups of vertebrates, researchers observed that birds, fish, amphibians and mammals followed different evolutionary paths. While mammals mostly provide maternal care, bony fish and amphibians exhibit several transitions to exclusive male care. See more news from Terra da Gente, on g1: SCIENCE: Dogs alter the behavior of pumas in protected areas, study reveals WATCH VIDEO: Giant otter is caught devouring huge cachara in the Pantanal; see video BEYOND DEFORESTATION: Diseases are also a concern in the conservation of Brazilian felines The father who leads hundreds of cubs The arapaima (Arapaima gigas) is one of the most emblematic examples of Brazilian fauna. According to researcher Ana Cláudia Torres Gonçalves, from the Mamirauá Institute, the male takes direct care of the offspring. "The cubs swim above their father's head, learning to breathe and feed. Meanwhile, the female remains close, warding off possible predators." According to the researcher, this care lasts about three months and significantly increases the survival of the puppies. The behavior recently observed in a video with approximately 400 puppies illustrates precisely this reproductive strategy. Watch the video: Arapaima couple with around 400 offspring goes viral on the networks This pattern helps to explain why paternal care is so common among fish. A meta-analysis with 48 species concluded that, unlike what is observed in many mammals and birds, caring for offspring does not normally compromise the physical condition of males. Even more surprising: in several species, females prefer to mate with males who are already caring for a litter, making parental care a real sexual attraction. Parents who fast and watch Emu (Rhea americana) szymon_bzoma / iNaturalist In birds, few examples are as extreme as that of the emu (Rhea americana). A study carried out by researchers at the University of Buenos Aires showed that the male builds the nest, incubates the eggs alone for around 42 days and gradually increases the time dedicated to the nest, going from 64% during laying to 97.5% at the height of incubation. Exits occur mainly during the hottest hours of the day, reducing the risk of embryos reaching lethal temperatures at night. After hatching, the father continues to care for the chicks for four to six months, devoting less time to feeding and more to vigilance against predators. According to biologist Joana Caito, this investment comes at a high price. "It is estimated that the male loses between 15% and 20% of his body weight during incubation. Even so, he continues to protect the young for several months, which shows the high energetic cost of this behavior." In Antarctica, the emperor penguin (Aptenodytes forsteri) takes this effort to the limit. While the female goes in search of food, the male remains incubating the couple's only egg during the winter. Emperor Penguin (Aptenodytes forsteri) michael_leven / inaturalist To survive the intense cold, hundreds of individuals continually group together. As Joana explains, these groupings are not static: they last, on average, around 1.6 hours and can temporarily raise the temperature inside the group to approximately 37.5°C, drastically reducing heat loss. When the father helps the mother reproduce more Golden Lion Tamarin (Leontopithecus rosalia) henrique_bitencourt / iNaturalist Among mammals, the golden lion tamarin (Leontopithecus rosalia) also defies common sense. The male spends much of his time carrying the young and gives them to the female, basically for breastfeeding. This behavior illustrates a pattern identified by researchers at the University of Hull, in the United Kingdom. By analyzing more than 500 species of mammals, they found that species in which males carry their young have shorter lactation periods and greater reproductive frequency. In other words, the father's help reduces some of the enormous energy cost of breastfeeding and allows the female to reproduce more quickly. "In some species, caring for young represents a huge sacrifice. In others, like many fish, being a good father can even increase the chances of winning new partners. The important thing is that all these strategies have evolved because they increase the chances of survival of the next generation", adds Joana. VIDEOS: Highlights Terra da Gente Watch this Saturday's Terra da Gente (1st), in full See more content about nature on Terra da Gente