Nautilus pompilius

Chambered Nautilus

Domain: Eukaryota

Kingdom: Animalia

Phylum: Mollusca

Class: Cephalopoda

Order: Nautilida

Family: Nautilidae

Genus: Nautlius

Species: pompilius

Taxonomy

Biome

Marine

(Coral Reefs)

Characteristics/Adaptations

The chambered nautilus is the only living descendent of a group of ocean creates that thrived in the seas 500 million years ago. Not a lot of adaptation has occurred in those years.
Its shell is divided into compartments. More compartments develop as a nautilus matures. As the organism grows, its body moves forward and a wall is produced that seals off older chambers. The animal can withdraw its body into its shell, closing the opening with a leathery hood. It has tentacles that have rides to allow it to grip to objects.
The shell also encloses a system that allows the animal to control its buoyancy. The older chambers of the shell have an argon-nitrogen gas mixture and a liquid saline solution that the nautilus has the ability to change. Therefore, the animal can control the ratio of liquid to gas.
The nautilus moves by pulling water it a cavity within the shell and blowing it out the siphon beneath the tentacles. The animal can then control the direction of the siphon.

Oxygen & Carbon Dioxide Exchange

When the chambered nautilus moves by ejecting water out of the siphon, there are four gills located just after the ventral mantle (before the siphon), that the water runs through/over. Cilia on the gills create a flow of oxygenate water through the mantle cavity, carrying off carbon dioxide and nitrogenous wastes. The dissolved oxygen is then transferred into the blood where it is taken back to the heart.

Circulation and Excretion

The chambered nautilus has a three-chambered heart and an open circulatory system. Two auricles collect the oxygenated blood from the gills and the ventricle forces this blood into blood vessels that bathes the tissues directly. The blood pools in small chambers (sinuses) until it is collected and carried back to the gills to be re-oxygenated.

The chambered nautilus has a coelom, which is a collecting place for waste fluids that are destined to be excreted. The beating of cilia pulls the fluid from the coelom, into tubular structures that recover useful sugars and salts. The rest of the waste then leaves the body through a pore that opens into the mantle cavity.

Nutrients

A chambered Nautilus is a scavenger that uses its calcified jaw to grind food. It is possible that they use their sense of smell to detect prey because they do not have good vision. Then then capture the prey with its retractable tentacles and pass it to its mouth where it is torn into pieces. Their diet mainly consists of hermit crabs and brachyuran crabs. The digestive system is made up of the buccal complex, the radula, jaw, crop, oesophagus, stomach, vestibulum, caecum, midgut gland, midgut and rectum. The food reaches the stomach very quickly and is reduced to small pieces. The indigestible food goes directly to the rectum where it is promptly excreted. The digested food remains in the stomach and crop for a long period of time as the stomach produces strong contractions and dilations. This is believed to help the distribution and breakdown of the nutrients throughout the body.

Resources

Picture: http://captainkimo.com/chambered-nautilus-cephalopod-from-siam-paragon/

Info: http://animaldiversity.org/accounts/Nautilus_pompilius/

http://www.aquariumofpacific.org/onlinelearningcenter/species/chambered_nautilus

http://jeb.biologists.org/content/205/11/1617

http://www.waza.org/en/zoo/visit-the-zoo/snails-cuttlefish-octopus-and-relatives-mollusca-1254385523/nautilus-sp.

http://www.tulane.edu/~bfleury/diversity/labguide/mollannel.html

http://www.iteachbio.com/Marine-Biology/MolluskSummary.pdf

http://www.seasky.org/deep-sea/chambered-nautilus.html

http://www.starfishfacts.org/starfish_facts_on_their_senses.html

Phylogenetic Tree: http://www.reed.edu/biology/courses/BIO342/2011_syllabus/2011_websites/CWEFEL_cephalopods/phylogeny.html

Reception and Response

A chamber nautilus’s eyesight is very poor, partly because they never adapted like other mollusks. Their eyes do not contain lenses so there is only a tiny hole to allow light into the eye. In order to capture its prey, it is believe that a chamber nautilus relies on its sense of smell (which is limited compared to most animals).

This organism does not have many interactions with its environment, other than searching for prey. When it believes it has found food, it will descend upon the victim and hold onto it with its tentacles. It will then proceed to place the prey into its mouth where it is grinded into pieces. All of its time is spent within the security of its shell, so it doesn’t have any defensive features.

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