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Nautilus (from Latin nautilus 'paper nautilus', from Ancient Greek ναυτίλος nautílos 'little sailor') [3] are the ancient pelagic marine mollusc species of the cephalopod family Nautilidae. This is the sole extant family of the superfamily Nautilaceae and the suborder Nautilina .
Nautilus have been noted to exhibit an extensive range of depth, close to 500 metres, however, they were demonstrated to be at risk of implosion when exceeding their depth and pressure limits. Depending on the species, the shells of live Nautilus will collapse at depths of 750 metres or deeper. [18] [4]
Because of their oceanic habitat, studies of their life cycle have primarily been based on captive animals and their eggs have never been seen in the wild. [7] Although nautilus have been kept at public aquariums since the 1950s, the chambered nautilus was first bred in captivity at the Waikiki Aquarium in 1995 (a couple of other nautilus species had been bred earlier) and captive breeding ...
Empty nautilus shells may drift a considerable distance and have been reported from Japan, India and Africa. Undoubtedly the same applies to the shells of fossil nautiloids, the gas inside the shell keeping it buoyant for some time after the animal's death, allowing the empty shell to be carried some distance from where the animal lived before ...
Miocene nautilids were still fairly widespread, but today the order includes only two genera, Nautilus and Allonautilus, limited to the southwest Pacific. The recent decrease in the once worldwide distribution of nautilids is now believed to have been caused by the spread of pinnipeds. [2]
If an earlier civilization existed on Earth millions of years ago, we might have trouble finding evidence of it -- but that doesn't mean it didn't exist.
When motionless, Nautilus can only extract 20% of oxygen from the water. [62] The jet velocity in Nautilus is much slower than in coleoids, but less musculature and energy is involved in its production. [75] Jet thrust in cephalopods is controlled primarily by the maximum diameter of the funnel orifice (or, perhaps, the average diameter of the ...
Nautilus does, however, have a leathery head shield (the hood) which it uses to cover the opening when it retreats inside. There are many forms of aptychus, varying in shape and the sculpture of the inner and outer surfaces, but because they are so rarely found in position within the shell of the ammonite it is often unclear to which species of ...