The Pet Tree House - Where Pets Are Family Too : Nautiluses The Pet Tree House - Where Pets Are Family Too : Nautiluses
Showing posts with label Nautiluses. Show all posts
Showing posts with label Nautiluses. Show all posts

Friday, April 10, 2015

According to the Fossil Record, Nautiluses Have Existed for About 500 Million Years


 A scientific look at the unusual nautiluses, including their eating habits, reproduction, and famously unique anatomy. 

The common misconception regarding the captive care of cephalopods is that long-term success is impossible. While it is true that keeping cephalopods is a difficult task, understanding their biology and natural behavior will enhance the success of the exhibition of these animals. The nautiluses are no exception. Though they may not have the chromatophores possessed by other cephalopods that enable color change, these deep-sea animals are a window into a world that most people will never see.

The nautilus differs from other cephalopods in many aspects both anatomically and behaviorally. The main body features of the nautilus are its shell, hood, and tentacles.

The chambered or pearly nautilus is a cephalopod (a type of mollusk)—a distant cousin to squids, octopi, and cuttlefish. Unlike its color-changing cousins, though, the soft-bodied nautilus lives inside its hard external shell. The shell itself has many closed interior chambers or “compartments.”

The animal resides in the shell’s largest chamber, while the other chambers function like the ballast tanks of a submarine. This is the secret to how the nautilus swims.

The tissue in a canal called the siphuncle [sigh-funk-el] connects all of the interior chambers. As seawater pumps through the living chamber, the nautilus expels water by pulling its body into the chamber, thereby creating jet propulsion to thrust itself backwards and to make turns. While swimming up or down through the water column, the nautilus uses its siphuncle to suck fluid into, or draw it out of, the smaller sealed chambers, allowing the animal to adjust its overall buoyancy.

According to the fossil record, animals similar to the chambered nautilus have existed for about 500 million years. Although no regulations currently exist to protect them, the six living species of chambered nautilus appear to be in decline. They are trapped mostly for their attractive shells and also for the shell’s inner layer, called nacre, which is used as a pearl substitute in jewelry and trinkets. In 2013, NOAA Fisheries funded a University of Washington researcher to conduct population studies of the nautilus in Fiji and American Samoa. The research should provide a clearer picture of nautilus abundance in those areas.

Shell and Hood

Similar to the cuttlebone in cuttlefish, the nautilus shell regulates the animal’s buoyancy, while at the same time providing protection against predators. The calcium carbonate shell is made up of individual chambers, some of which are filled with gas and others filled with seawater. The chambers are interconnected by a tube, or siphuncle. The liquid-filled chambers release or take in sea water in order to maintain neutral buoyancy.

The body of the nautilus lies within the first chamber and can retract into this chamber if in danger. In the retracted state, the hood protects and conceals the animal from predators. This behavior is its only known defense mechanism. While most cephalopods possess an ink sac that can be used as a defensive tactic, the nautilus is without an ink sac.

Tentacles

Nautiluses are equipped with a total of 90 adhesive tentacles, without suckers, significantly more than any other cephalopod. Utilizing its 90 tentacles, the nautilus is able to feel around the ocean floor or rocks searching for prey. Vision in the nautilus is much less developed than in other cephalopods; the eye lacks a lens and is constructed like the aperture of a pinhole camera (Hanlon & Messenger, 2005).

The last major difference between nautilus and other cephalopods is their life span. While most cephalopods have a life span of one to two years, the nautilus is thought to live up to at least 15 years, a very attractive characteristic for an aquarium animal.

Feeding

Wild nautiluses have been observed to make diel migrations (Carlson et al., 1984; Ward et al., 1984). This type of behavior takes the nautilus from depths of 1200 feet at daybreak up to depths of 300 feet by sunset. Nautiluses can best be characterized as opportunistic feeders investigating food when detected. The actual feeding behavior of the nautilus can be described as sampling, searching, and sweeping.

There is evidence to support that the nautiluses detect prey by sampling lateral currents across the reef for chemical trails (O’dor et al., 1993). After detecting prey with the use of large olfactory organs, the tentacles are used to locate and seize the prey. The diet of the wild nautilus includes crustaceans (including hermit crabs; Ward & Wicksten, 1980), crustacean molts, nematodes, echinoids, and fishes (Saunders & Ward, 1987). There are accounts of cephalopod beaks and nautilus tentacles found in the gut as well (Hanlon & Messenger, 2005). It is not uncommon under aquarium conditions to witness cannibalism (Carlson, 1987) as is observed with other species of cephalopods.

The main focus in the feeding of nautiluses is to provide food that is high in calcium in order to sustain normal shell growth. The most common food offered to nautiluses in captivity is shrimp (with shell), squid, various types of frozen fish, and blue crab. Several different types of molts, such as lobster molts, have also been fed as an enrichment food. The lobster molt is taken quickly and consumed with no problems (molts are also a great source for calcium).

Shell Aberrations

A common and still misunderstood issue with captive nautiluses is aberrations of the shell. Over time, the shell does not grow normally and begins to degrade. Signs of this are black edging of the newly formed shell. There appears to be no adverse health issues associated with the shell malformation, and to date is merely an aesthetic problem.

Aquarium Care

Tank Size

Although nautiluses spend most of the time attached to the walls of the aquarium, they do occasionally jet around with minimal control, often running into the sides of the tank. For this reason the dimensions of their accommodations are important for the proper care and maintenance of nautiluses. For the average nautilus (less than 6 inches), the aquarium should be at least 3 feet long, 18 inches wide, and 2 feet deep to allow the animal to move around freely without constantly bumping into the sides of the tank; however, when keeping multiple nautiluses or a single large nautilus, a bigger aquarium is required.

Filtration

As with all cephalopods, a key ingredient in successful husbandry is proper filtration. Due to the high amount of solid and liquid waste produced, it is important to have a large biological filter bed or sand filter. A protein skimmer is also recommended to help manage the large waste load. UV sterilizers can be added to help minimize the spread of possible pathogens, which can be difficult to treat in cephalopods. A good rule to go by is to have a filtration system that is designed for a tank twice the size of the one the animal is in.

Temperature

Another important aspect of keeping nautiluses alive is maintaining the water temperature between 50° and 70°F, using a chiller. For a more natural environment and to aid possible breeding, one can have the temperature gradually fluctuate between cooler and warmer temperatures over a 24-hour period. This will mimic diel migration, although this will be difficult without a computer controlling the heater/chiller. Because nautiluses live in the deep sea and receive only minimal light when migrating to the surface at night, there should only be enough light in the tank to view the animal. Actinic lights work well for this, as too much light can stress the animal.

Aquascaping and Tankmates

Careful consideration should be used when deciding how to decorate the tank and choosing tankmates. Live rock can be used on the bottom and sides of the tank, but the mid and upper sections of the tank should be clear of obstacles that the nautilus could run into and damage itself. There should be no plastic décor, as nautiluses have a habit of trying to bite/eat everything.

The nautilus is one of the few cephalopods with which other animals have been kept in the same tank with some success, but keep in mind that there is always the chance that those animals could become a snack. If choosing to have tankmates, make sure they are non-aggressive and can withstand the cold water and dim lighting nautiluses require. Possible tankmates include cardinalfish, squirrelfish, pinecone fish, flashlight fish, shrimp, sponges, snails, and non-stinging corals that can live in low light.

Reproduction

The understanding of nautilus reproduction has increased substantially in the past 20 years owing much to the pioneering work of Dr. Bruce Carlson at the Waikiki Aquarium (Carlson, 2000). There are two methods in determining the sex of a nautilus. The first is best used on new animals not accustomed to captivity. By turning the animal upside-down, a horseshoe-shaped gland will be visible in females and will be green to brown in mature females. This technique, though, should only be used by advanced aquarists. The second technique of sexing a nautilus is to locate the spadix, which is a large modified tentacle found on the left side of the male nautilus, adjacent to the mouth. The spadix is the mode of sperm transfer.

Nautiluses mate facing each other and may stay in that position for hours. The first embryo was discovered in 1985 and the first hatchling was obtained in 1988 (Norman, 2000). In captivity, female nautiluses may lay one to two eggs per month. The nautilus egg will take at least one year to hatch. The temperature of the egg-holding tank is crucial in the development of the embryo.

While most nautiluses are kept at temperatures of 64°F, the eggs actually develop at warmer temperatures, 70° to 75°F. Once hatched, the juvenile nautilus readily accepts food. Unfortunately, there has been no success in rearing adults from eggs as of yet.

Difficult Yet Rewarding

The task of exhibiting the nautilus can be very overwhelming when considering tank design, filtration units, and tank decor. Nevertheless, a keen awareness and understanding of nautilus biology and behaviors will assist you when you begin to assemble your tank. As Jacques Cousteau said, “The impossible missions are the only ones which succeed.”

References
Carlson, B. A., McKibben, J. N., & DeGruy, M. V. 1984. “Telemetric investigation of vertical migration of Nautilus belauensis in Palau.” Pacific Science 38:183–188.












FOLLOW US!
/

Friday, April 3, 2015

Can You Keep Cephalopods As Pets?


Cephalopods, the class of mollusks which scientists classify octopuses, squid, cuttlefish and nautiluses, can change color faster than a chameleon. They can also change texture and body shape, and, and if those camouflage techniques don't work, they can still "disappear" in a cloud of ink, which they use as a smoke-screen or decoy. Cephalopods are also fascinating because they have three hearts that pump blue blood, they're jet powered, and they're found in all oceans of the world, from the tropics to the poles, the intertidal to the abyss. 

Cephalopods have inspired legends and stories throughout history and are thought to be the most intelligent of invertebrates. Some can squeeze through the tiniest of cracks. They have eyes and other senses that rival those of humans.

Usually, hobbyists interested in keeping a pet cephalopod should stick with Octopus or Cuttlefish - Squid don't survive well in aquaria) should first consider buying one at their local aquarium store. Even if they don't regularly stock cephalopods, most good saltwater shops can special order an octopus (and in rare cases, a cuttlefish) if it is requested. 

The main advantage one gains by going through a pet store is in cost—and it's a big difference. Because pet stores buy through distributors and in bulk quantities, a cephalopod at the local shop will cost nearly half of what it would to get through the mail: overnight shipping is expensive and saltwater is heavy; not to mention if the shipment has to cross a national border and become mired in red-tape permits and government bureaucrats that think cuttlefish are fish and octopuses are not because the word fish is not part of their name. Although some retailers will require a deposit to cover their risk, another advantage to the consumer lies in the fact that you normally get to examine the animal and ask the shop owners and caretakers questions about it before you make it your pet. 

Here's The Caveat:

Most shop owners lack specific knowledge about cephalopods, their care requirements, and species information. The online shops and mail-order houses are usually no better about it. In fact, most of what the industry knows about cephs is from trial-and-error and long-standing rumors—rumors that don't favor our soft friends. Many will slap the omnipresent O. vulgaris or O. joubini tag on their animal and sell it as such, regardless of where it came from or what it actually is. The animal you receive could be a baby with the potential to grow very large, or it could be a full grown adult of a small species that may have only weeks left in it's natural lifespan. 

Most octopuses in the aquarium trade are in the small to medium size range as adults—rarely larger than a grapefruit. Both scientists and hobbyists alike find frustration in finding transportation for their cephalopods, and international orders will need to address permits to cross national borders. 

In addition to costing more than many marine fish and invertebrates, none of the cephalopod family tolerate shipping stresses well, and there's always the chance of inking during shipment. 

Most other type of cargo has higher priority than live fish and invertebrates, and some of the species listed below are only available in certain seasons. Also, the prices below do not include shipping costs—which can be over $50 for the smallest specimens and thousands for the largest. 

Things to think about before you buy a cephalopod:

1. Home aquarists and scientists agree- cephalopods can be really hard to keep alive in a tank. They require a very clean, stable seawater system, escape proof lids, and they are picky eaters. Keeping one can be expensive, and feeding one can be expensive.

2. While some countries have strict collecting laws, many tropical animals are collected from the wild using irresponsible and illegal methods such as poaching and/or “cyanide fishing”. Cyanide fishing involves squirting cyanide into the reef and breaking coral to dig out the poisoned, stunned animals. It kills coral, other invertebrates, and fish. Ask your aquarium shop for tank-raised animals.

3. It might be deadly. Blue-ringed octopuses are deadly. There is no anti-venom for their bite. Other octopuses are so poorly known that we don’t even know how dangerous they might be. Relatives of Abdopus aculeatus have a poison in their bodies that’s similar to TTX, the poison in blue-ring venom (Robertson et al. 2004 Toxicon 44: 765). Striking animals like “Wunderpus” and the “Mimic” might be highly venomous. It appears that the skin of the "Flamboyant" cuttlefish is toxic. You don’t want to be the one who finds out. 

4. It might be rare, so taking a wild animal might put those cephalopod populations at risk.

5. It might try to crawl out. Octopuses are well-known for their abilities to escape aquaria. Intertidal species are notoriously hard to keep in a tank. If it goes walkabout when you’re not looking, then you will find a dead octopus on the floor the next morning, or behind the couch in two years. 

6. It might eat your other pets. Crabs, clams and sometimes snails are not safe from the voracious appetite of a cephalopod. Often fish will either eat your cephalopod or be eaten by your cephalopods.

7. They don’t live very long, most species only about a year. By the time you get your tropical cephalopod, it is an adult near the end of its live span. You’ll be lucky to keep it alive for a few months







FOLLOW US!
/