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Home › Ocean Life › Marine Animals › Invertebrates › Mollusks › Nautiluses

Fascinating Facts about Nautilus Species

[Nautilus Phylum: Mollusca] [Class: Cephalopoda] [Subclass: Nautiloidea] [Family: Nautilidae]

A family of ancient marine cephalopods that look like living fossils are only found in the eastern Indian Ocean and parts of the western Pacific.

This section contains facts and information about nautilus mollusks, including where they live, what they eat, and how these primitive creatures reproduce.

Nautiluses Geographical Range and Habitat

The nautilus species is a deep sea mollusk that thrives best in the deep tropical and subtropical waters of the Indo-Pacific, such as:

• Australia (e.g. the Great Barrier Reef and New Caledonia)
• Fiji
• Indonesia (moreso at the Maluku Islands and Bali)
• Papua New Guinea (including the nearby Solomon Islands)
• Vanuatu
• The Philippine Islands (especially around Bohol and Palawan)

Pro Tip: Despite being in existence for centuries, in fact nautiloids were around before the dinosaurs, none of the native populations of nautiluses exist in the Atlantic Ocean, the Caribbean Sea, or any of the European dive sites (e.g. the Mediterranean Sea).

Nautilus spend most of their life in deep water environments, such as in depths ranging between one hundred and seven hundred (700) metres (deeper than 2,000 feet).

But, it's not uncommon for scuba divers to see them swimming along shallow reef slopes, limestone escarpments, and the middle light zone (mesophotic area) when they're scavenging for food.

Even though the preferred habitats of nautiluses tends to be areas with rocky substrates and deep reef drop-offs, they steer clear of large open areas of sand or mud.

Nautilus Characteristics and Behaviour

Their shells are made from the carbonate ion compound that exists in seawater. You might call it the building block for the skeletons and shells of many marine organisms, especially coral formations and shellfish.

These inner chambers help to regulate their buoyancy in the water column and they increase in numbers as they grow older. However, the main nautilus anatomy exists only in the outermost chamber.

But wait - there's more:

Nautiluses have up to ninety (90) suckerless tentacles protruding from the chambered shell and a beak that they use to crush their favourite prey - sea shrimp.

Compared with many of the marine molluscs, nautiluses have poor eyesight. In fact, scientists believe they rely on their sense of smell to locate food sources.

What Do Chambered Nautilus Eat?

These ancient creatures use a siphon to swim and migrate to shallower depths at night to hunt. Even though their daily diet will include different types of shrimp species, they are opportunistic scavengers that also eat a range of other nutritional organisms, such as:

• Algae
• Carrion (carcasses of dead fish)
• Crustaceans (e.g. hermit crabs, lobsters)
• Marine mollusks (especially bivalves and gastropods)
• Small "slow-moving" benthic fish
• Soft-bodied invertebrates
• Worms (polychaetes)

Pro Tip: Some nautilus species are known to be "cannibalistic animals" and will eat other small or weak nautiluses.

List of Nautilus Species

How Do Nautiluses Reproduce?

Nautilus reach reproductive maturity after the age of ten (10) and they can live up to twenty (20) in the wild. But, one of the main reasons for slow population recoveries is that nautilus reproduction is unhurried and seasonal.

Despite having separate genders (male and female), there are few obvious signs of sexual dimorphism. However, the males tend to be smaller than the females and there are some subtle differences in tentacle and mantle cavity structures.

At an appropriate time of year, often determined by a shift in water temperature, courtship and the mating process begins - usually occurring "face-to-face".

Here's the thing:

The male uses a spadix (a conical shaped tentacle-like organ) to transfer a spermatophore (a packet that contains his sperm) into the mantle cavity of the female.

During the initial fertilisation process, the eggs are leathery and measure around three (3) centimetres long. The female attaches the eggs to hard deep-water structures, such as coral and rocks.

There is no parental care and the eggs are abandoned by the adults to develop on their own. It takes between nine months and one year for the eggs to hatch.

Nonetheless, once the hatchlings have emerged as fully formed miniature nautiluses, they will already be capable of swimming and hunting for food.

Threats and Predators

Many of the nautilus populations are considered as severely threatened, mostly due to their low reproductive rates, slow growth patterns, and late adulthood.

Moreover, nautilus shells have become a commercial target and they're often used for artwork, items of furniture, and jewelry.

In the wild, the biggest threat to nautiluses comes from being eaten by sharks, octopuses, large bony fish (such as groupers), and triggerfish.

Important: The IUCN Red List of Threatened Species is a comprehensive source of information about the global conservation status of animals, fungi, and plants. Currently, the IUCN lists most of the nautilus types as being Near Threatened (NT).

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