The Nautilus - Everything You Need To Know - Octolab TV (2024)

Even if your knowledge is restricted to what you have read on a seafood restaurant’s menu, you are all more or less familiar with the octopus, the squid, and the cuttlefish.

But the fourth animal that completes the class of cephalopods is most probably an alien to you.

This cephalopod, however, does not deserve its anonymity: if it could talk, it would have thousands of stories to tell… Nautiluses have been around even before dinosaurs! In fact, according to paleontologists, the nautilus appeared 265 millions years before dinosaurs roamed the earth.

The truth is that the nautilus looks very different from the rest of the cephalopods (mainly because of its shell) and it is impressive how this slower and not-so-bright cephalopod has managed to survive for so many millions of years.

The nautilus is:

• An invertebrate meaning that it does not possess a spine.
• A mollusc, which is a phylum of the invertebrate animals. Almost one quarter (23%) of all marine animals are molluscs. But the majority of molluscs are terrestrial organisms: 80% of all molluscs are gastropods (snails, slugs etc.) One of the main characteristics of the mollusc is the existence of a mantle cavity. The word mollusc derives from the ancient Greek word “malákia” which means soft.
• A cephalopod, which is a class of molluscs, containing also octopuses, squids and cuttlefishes. They are otherwise known as inkfishes as they are all able to expel ink. The word cephalopod translates from Greek as head-feet. They are named like that to refer to their prominent heads and pairs of arms or tentacles.

The meaning of the word nautilus (from the Greek ναυτίλος nautílos) is ‘sailor’ as in antiquity the word was used to describe the Argonaut Octopus, which, according to Aristotle, used their arms to “sail” on the sea surface. The Argonaut Octopus is also known as the paper nautilus but it should not be confused with the nautilus, as the Argonaut is an octopus species, whereas the nautilus is a completely different marine creature with several different species.

Unlike other cephalopods, which can be found almost everywhere in the world, the nautilus’ distribution is restricted to the southwestern Pacific Ocean, the Philippines, Indonesia, and the tropical seas of Australia.

The nautilus is a pelagic species and a deep sea inhabitant, active both during the day and during the night. It can cover considerable distances, moving to up to 6 km in a single day.

The nautilus can be found along the slopes of coral reefs. It cannot move to very shallow waters, as its preferred water temperature is below25 °C (75 °F), nor can it move too deep as its shell will implode at a depth of more than 800 meters.

It has long been believed that nautiluses move at a depth range of 600–2,000 feet during the day (180-600 m) and at about 300 feet (90m) below the surface during the night. In this way, the nautilus stays hidden from the threat of its predators at the deepest parts of the sea and moves further up during the night to feed.

However, recent studies that used more advanced technology have proved that individual populations of nautiluses move higher or deeper in the water column for various reasons (such as the habitat’s specific characteristics), and not so much according to this day and night pattern.

Sadly, the nautilus is an endangered species. Its beautiful shell, which forms a logarithmic spiral, has long been used for the creation of fine jewelry and decorative items, thus making it a commodity of high demand. Fortunately, international trade of the nautilus’ shell is nowadays illegal although many brainless merchants still try to profit from the beauty of this rare and long-surviving creature.

The nautilus is most often described as a living fossil, although recent studies have proved that this characterization is not very accurate. The nautilus appearance dates back to the Late Cambrian period, when they were the masters of the seas long before the ascent of fishes and marine animals.

About 200 million years ago, the nautilus populations were thriving. Back then, it is calculated that there were about 10.000 different species of nautiluses.

The reason why nautiluses are called living fossils is that their shells look so similar with the 500-million-year-old preserved specimens of ancient nautiluses’ shells. But although it was believe that the nautilus have seized to evolve, a study of the nautilus’ genetics has shown that the nautilus is able to evolve very quickly, and is even capable of producing new species.

• The tentacles: The 60 to 90 appendages of the nautilus (the number depends on the species) are not tentacles per se. Rather, they are cirri similar to the ones of some deep-sea octopuses such as the Dumbo Octopus and the Glowing Sucker Octopus. The cirri are long, flexible and retractable. They are suckerless, with alternating grooves and ridges that allow it to grip objects.
• The beak and radula: Similar to other cephalopods, the nautilus has a parrot-like beak which is used to tear the flesh of its prey apart. The tongue-like radula of the nautilus has nine teeth.
• The eyes: The eyes of the nautilus have no solid lens and so the nautilus has a much poorer vision than other cephalopods.
• The funnel: The funnel or siphon of the nautilus is located on the lower side of the shell. It is used to regulate the buoyancy of the nautilus as well as for jet propulsion.
• Nervous system: Whereas the nervous system of the nautilus is less sophisticated compared to other cephalopods which are capable of “higher learning”, an experiment has proved that nautiluses, like other cephalopods, have both a short-term and a long term memory.

The nautilus can be an easier target compared to other cephalopods which are faster and can camouflage themselves more effectively.

In fact, the nautilus mainly depends on its shell for its protection. The crusty nautilus, in fact, has its shell covered with a slimy protein-dense skin to avoid the grasp of the octopus. Other nautilus predators include sharks, triggerfishes, and sea turtles.

The nautilus is mainly a scavenger. It feeds on the remains of dead fishes or the molts of lobsters and crabs. The nautilus is also an opportunistic hunter. Its prey includes shrimp, crabs, fishes, and occasionally even other nautiluses. Scientists believe that nautiluses mainly rely on their smell to track their victims due to the lack of good vision.

Being slower than other cephalopods means that nautiluses need to consume less energy. Therefore, the nautilus can survive with even one meal per month!

There is still a lot of mystery surrounding the reproduction processes of the nautilus. Up to now, scientists have not managed to witness egg laying in the wild and only a handful of efforts to produce fertile nautilus eggs in captivity have been fruitful.

One important aspect that differentiates the nautilus from the rest of the cephalopods is that the nautilus is not semelparous. This means that it can reproduce multiple times during its lifetime.

This is why the nautilus has a much longer life span than other cephalopods. Some nautiluses can live for more than 20 years!

Instead of one specialized reproduction arm (like the octopus’ hectocotylus), the male nautilus has four specialized tentacles which form its sexual organ called the spadix. The spadix is used to transfer the sperm packet from the male to the female. It is located on the left side of the mouth and looks like a spike or shovel.

Since the nautilus can reproduce multiple times during its lifetime, it produces fewer eggs than the octopus or the squid. Each time the female octopus lays about 12 eggs, which are also way bigger than other cephalopod eggs. A female nautilus of six or seven inches may lay an egg measuring 2 inches!

Observations from eggs raised in captivity suggest that the embryo needs about a year to hatch. Unlike other cephalopod hatchlings which have amazingly fast growth rates, the nautilus reaches maturity in about 15 years!

Classifying the living species of nautiluses is not such a nightmare as the octopus or the squid. There are, as far as we know, only six living species which are:

• The Crusty Nautilus
• The Chambered Nautilus
• The Bellybutton Nautilus
• The Palau Nautilus
• The White-Patch Nautilus
• Allonautilus perforatus (which is the least-known and studied among the six, and therefore has no common name.)

Some genetic researchers consider only the first three as separate species and the rest as subspecies.

The Chambered Nautilus (Nautilus pompilius) is the most commonly found species and that is why its name is sometimes used to refer to all nautiluses.