Animal Armageddon
Coiled Nautiloid
From Past to Present: Coiled nautiloids belonged to a group of marine mollusks called "nautiloids," all of which possess an external shell; the best-known living examples are the modern nautiluses. Ancient nautiloids flourished during the early Paleozoic era, where they constituted the main predatory animals. They developed an extraordinary diversity of shell shapes and forms. Some 2,500 species of fossil nautiloids are known, but only a handful of species from this ancient group survived to the present day. The nautiloids are among the class of animals called the cephalopods, which includes octopus and squid.
A Coiled Shell: There are three key features which are common to the shells of the nautiloids. These are the internal chambers, the siphuncle and the sutures of the shell — features that are also found in the shells of all modern nautiluses. The thin walls between the internal chambers (camerae) of the shell are called the septa. As the coiled nautiloid grew, it would detach its body from the walls of the shell, move forward and secrete a new septum behind it. Each septum added created a new camera in the shell. The body of the animal itself occupied the last chamber of the shell — the living chamber. The shell, or cone, could grow to about 1 foot in diameter and had mathematically perfect whorls.
Freaky Features: The coiled nautiloid had 16 tentacles with segmented ridges on the inner pads. Halfway down, the tentacles change to more of a smooth, spaghetti-like shaft. The coiled nautiloid had a glossy black beak, like a parrot's, that was useful for snapping through tough shells as it devoured its prey. The coiled nautiloid moved much in the same way as its relative, the straight-shelled nautiloid. |
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As seen in ANIMAL ARMAGEDDON: Episode 1 — "Death Rays"
 Watch the Animal Armageddon preview.
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Coiled Nautiloid: CUTE or CREEPY? Rate its fright factor in Prehistoric Scary or Not?
Want to know more about the coiled nautiloid's modern relative, the nautilus? Visit HowStuffWorks.com. |
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