platypus feet considered flippers or paws

#Platypus feet considered flippers or paws free#

Tetrapod limbs which have evolved into fin-like structures are usually (but not always) called 'flippers' rather than fins. However, the hydrodynamic control surfaces of fish are always referred to as 'fins' and never 'flippers'. Usage of the terms 'fin' and 'flipper' is sometimes inconsistent, even in the scientific literature. manatees and dugongs), and marine reptiles such as the sea turtles and the now-extinct plesiosaurs, mosasaurs, ichthyosaurs, and metriorhynchids. walruses, earless and eared seals), sirenians (e.g. In animals with four flippers, such as pinnipeds and sea turtles, one may distinguish fore- and hind-flippers, or pectoral flippers and pelvic flippers.Īnimals with flippers include penguins (whose flippers are also called wings), cetaceans (e.g. In animals with two flippers, such as whales, the flipper refers solely to the forelimbs. It refers to the fully webbed, swimming appendages of aquatic vertebrates that are not fish. Instead, they remain a key tool, allowing northern seals to exploit niches not – or perhaps no longer – available to most of their kin.A flipper is a broad, flattened limb adapted for aquatic locomotion. Cases like the grey seals also show that claws are not just an evolutionary hangover. Their claws connect northern seals with their ancient past, and help us understand how their ancestors conquered the ocean. Somewhat shockingly, they even fed on members of their own kind. Grey seals prey on other marine mammals, using their paws and claws in the process. The true nature and cause of these wounds was revealed only recently.

Grey seals, in particular, have put this skill to deadly use.įor years, scientists have noted carcasses of harbour porpoises and various seals with peculiar spiral injuries. Mobile paws may give seals an advantage when handling large prey. Renae Sattler, Alaska SeaLife Centerīut there is also a more sinister part to this story. See how the claws dig deep into the salmon, helping the seal to keep a firm grip on its prey. Harbour seal stretching a fish between its teeth and strong claws during feeding experiments carried out at the Alaska SeaLife Center as part of this study.

#Platypus feet considered flippers or paws free#

Their paws thus remained free to perform other tasks, and simply kept doing what they always had done. Unlike their close relatives, the fur seals and sea lions, northern seals primarily swim with their hind limbs. The answer, partly, is simply because they could. Given the importance of clawed forelimbs to ancient seals, why are northern true seals the only ones that still use them? Clawed forelimbs: a relic of the ancient past or useful modern adaptation? Rather than changing all at once, the behaviour and anatomy of early seals changed gradually, remaining effective at each step along the way. This gradual transition helped to smooth the switch from feeding on land to hunting underwater. Later seals lost the sharp cutting teeth of Enaliarctos, but retained its ability to grasp prey. But unlike modern seals, these ancestral species still had sharp cutting teeth that may have allowed them to chew their food while hauled out on the shore. Like the modern Northern seals, ancient species like Enaliarctos likely used their forelimbs to help process prey into pieces.