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The image below is a photo of the exhibit panel. Following it is a transcript of the panel.

Photo of the panel from the exhibit.

An ancient group of marine animals, nautiloids have changed very little in more than 500 million years.

Nautiloids were among the first swimming predators. They use "water-jet propulsion" to swim, and have shells with separate chambers for buoyancy control. Like their octopus relatives, nautiloids have tentacles around the mouth.

Nautiloids ( NAWT -ih-loyds): swimming marine mollusks with chambered external shells

New feature:

    Chambered shell for buoyancy control; fluid levels within separate chambers regulate buoyancy at various depths and pressures

When? 550 million years ago to present

PICTURE CAPTIONS:

  • siphuncle: a fleshy tube that links shell chambers; used to adjust fluids within chambers to regulate buoyancy
  • suture: a curved seam that marks the place where the septum joins the outer shell wall; strenghens shell
  • septum a shell partition that separates chambers; forms behind the animal as it grows forward in the shell; strenghtens shell
  • Diagram showing common ancestry and evolution of nautiloids, ammonoids, and squid/octopus from organisms with a shell modified for buoyancy, head with tentacles, and water-jet propulsion. Evolution of maximum of ten arms is where ammonoids and squid/octopus branch off.