Animal Armageddon
Straight-Shelled Nautiloid
The Great White of Its Time: During the Paleozoic Era, the straight-shelled nautiloid ruled the seas. The great white shark of its time, it was a merciless killer feared by all. This perfectly designed killing machine was up to 20 feet long — 15 feet of shell plus 5 feet of head and tentacles — and had an insatiable hunger. A chambered, gas-filled shell kept this 300-pound beast buoyant. It sliced through the sea by inhaling water then forcing it out through a small muscular tube at the base of its shell.
Nautiloid Anatomy: Also known as the orthocone nautiloid, the straight-shelled nautiloid had a semi-flexible hood composed of tough, warty skin that draped over its eyes. It had eight tentacles for grasping prey, which extended from its head. These lacked suckers, but instead had segmented ridges for gripping slippery meals. Chromatophores in the skin let the nautiloid change color, though in general the underside remained white. The long, pointed shell was white with magenta stripes, though when underwater the colors deepened.
Forwards and Backwards: Straight-shelled nautiloids traveled shell first with the hyponome — a small, flexible propulsion tube — pointed to the rear. The hyponome squirts out water like a jet. Water pushed through the hyponome was thrust out by the head pistoning in and out of the shell (the nautiloid's living chamber). When attacking the nautiloid reversed direction, traveling tentacles first with the hyponome directed shellward. This reverse method of travel was slower because the tube was not fully inflated as it bent over the shell, yet it was still highly effective. |
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As seen in ANIMAL ARMAGEDDON:
Episode 1 — "Death Rays
 Watch a Video of the Straight-Shelled Nautiloid.
COULD YOU SURVIVE? Take the "Staying Afloat in the Age of Sea Creatures" QUIZ to find out.
Straight-Shelled Nautiloid: CUTE or CREEPY? Rate their fright factor in Prehistoric Scary or Not?
Is there a modern-day mollusk even more horrifying than this? Perhaps... Meet the giant squid at Science Channel.com. |
NEXT CREATURE: Trilobites »
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