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Ward's World + MGH Sphenisciformes

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Sphenisciformes (continued) By this time, the sea ice has melted back close to the site of the nesting colony. Habitat Penguins are found primarily in the cold southern oceans, on the Antarctic continent and its surrounding islands, as well as northward to Australia, New Zealand, South America, and Africa. One species, comprising the Galápagos penguins (Spheniscus mendiculus), is found in the Galápagos Islands, which are on the Equator, but are surrounded by the cold Humboldt Current. Fossil record The fossil record of the penguins begins in the late Eocene and continues throughout the Tertiary. Fossils have been found in Antarctica, Australia, and South Africa, approximating the range of present-day penguins. The earliest fossil penguins were already well specialized as flightless, wing-propelled swimming birds, and their fossil history provides little new information about the evolutionary history and distribution of the group. Some fossil penguins were much larger than the emperor penguin [which can reach 120 cm (48") in height and is the largest living species]. Some Eocene species were gigan- tic (possibly reaching 180 cm (72") in height] and had a long spearlike bill. Fig. 2: Adélie penguin (Pygoscelis adeliae) incubating eggs. (Credit: iSTOCK ) Penguins are gregarious, breeding in large colonies along coastal areas. The emperor penguin (Aptenodytes forsteri) also breeds on ice packs along the Antarctic coasts during the fall. The males and females, which are identical, form strong pair bonds and share in the incubation and care of the downy nestlings. The older young of some species are kept in large groups, or crèches. Incubation of the one egg is the responsi- bility of the male (Fig. 2), which remains on the nest for over 2 months in the winter without eating. The females leave the breeding colony during this period to feed, and return fat and laden with food for the young. Males then leave for the ocean and return with food to relieve the females. This alternation continues until the young are old enough to enter the water. + ward ' s science 5100 West Henrietta Road • PO Box 92912 • Rochester, New York 14692-9012 • p: 800 962-2660 • wardsci.com This article was originally published by McGraw Hill's AccessScience. Click here to view and find more articles like this.

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