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They are strong fliers; their broad, blunt-tipped wings require faster wing-beats than those of many ducks and they take off with some difficulty. Northern species tend to be migratory ; southern species do not migrate though the hardhead travels long distances on an irregular basis in response to rainfall.
The evolution of flippers in penguins was at the expense of their flying capabilities, in spite of evolving from an auk-like ancestor that could 'fly' underwater as well in the air. Form constrains function, and the wings of diving flying species, such as the murre or cormorant have not developed into flippers. The flippers of penguins became ...
The physiology of underwater diving is the physiological adaptations to diving of air-breathing vertebrates that have returned to the ocean from terrestrial lineages. They are a diverse group that include sea snakes , sea turtles , the marine iguana , saltwater crocodiles , penguins , pinnipeds , cetaceans , sea otters , manatees and dugongs .
The white-throated dipper and American dipper are also known in Britain and America, respectively, as the water ouzel (sometimes spelt "ousel") – ouzel originally meant the only distantly related but superficially similar Eurasian blackbird (Old English osle). Ouzel also survives as the name of a relative of the blackbird, the ring ouzel. [6]
[citation needed] Plunge-diving birds are notable for their beaks, necks, and morphing wings. Plunge-diving birds generally have a higher beak angle ratio than others. [ 5 ] Beak angle ratio is defined as the top angle divided by the side angle.
Diving equipment, or underwater diving equipment, is equipment used by underwater divers to make diving activities possible, easier, safer and/or more comfortable. This may be equipment primarily intended for this purpose, or equipment intended for other purposes which is found to be suitable for diving use.
An underwater glider is a type of autonomous underwater vehicle (AUV) that employs variable-buoyancy propulsion instead of traditional propellers or thrusters. It employs variable buoyancy in a similar way to a profiling float , but unlike a float, which can move only up and down, an underwater glider is fitted with hydrofoils (underwater wings ...
The entry requirements for diver training depend on the specific training involved, but generally include medical fitness to dive. Fitness to dive, (also medical fitness to dive), is the medical and physical suitability of a diver to function safely in the underwater environment using underwater diving equipment and procedures.