Saturday, October 20, 2012

Chambered Nautilus

Nautilus pompilius
The Nautilida Order contains six extant species and a handful of extinct ones, some of which date all the way back around 550 million years. They are primitive Cephalopods that often are given the "living fossil" moniker-- they have changed very little over the past several million years.

The Chambered Nautilus is perhaps the best known of the bunch. They are large in size (one subspecies reaches just under a foot in shell diameter) and have a very widespread distribution across the Pacific.

The shell of the Chambered Nautilus is covered in dark and light stripes-- a coloration pattern that camouflages them. The shell serves as protection, and also helps with buoyancy  as the Nautilus can fill and empty out different pockets with gas. As they grow, the shell gains new chambers, and full grown adults will have around 30 different compartments.

Aside from the shell, the Chambered Nautilus displays several other interesting traits. For one, they have no lenses or corneas in their eyes. Secondly, they have around 90 tentacles, none of which have suckers (something most other Cephalopods have).

The Chambered Nautilus is a very slow growing creatures. They are between 15 and 20 years old before they reach sexual maturity. Reproduction takes place internally, with four of the males' tentacles forming a part called the spandix. They use this to transfer a spermatophore mass to the female. The mass attaches to the female's mantle and releases the sperm. Newly hatched babies have shells that measure about 1in in diameter.

Back during the Renaissance, Chambered Nautilus shells were very popular with artists and collectors. They would attach the shells to metal stems, forming decorative cups. Some got exceptionally elaborate-- like this piece using guilt silver that looks like an Ostrich!

IUCN Status : Not Listed
Location : Pacific Ocean
Size : Shell Diameter up to 10in (25cm)
Classification : Phylum : Mollusca -- Class : Cephalopoda -- Order : Nautilida
Family : Nautilidae -- Genus : Nautilus -- Species : N. pompilius

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