Cephalopods: Octopuses and Cuttlefishes for the Home Aquarium

It's December, and Squidmas is coming. Maybe you're like me, and the kids have all moved out, so you're thinking having a little intelligent life at home would be nice. Or maybe you're kids are still home, and you think they'd love a pretty pet. Or maybe you just love cephalopods, as do we all, so you're thinking, hey, let's get an aquarium and an octopus! What a fun idea!

One word of advice: NO. Don't do it. You can't just rush into these things.

Here's a positive suggestion, though. Start reading TONMO, the octopus news magazine online, regularly. If you haven't been reading it already, you aren't worthy of owning a cephalopod anyway. If you start dreaming about tentacles, then maybe you can consider feeding your obsession by planning to get a cephalopod of your own.

Second positive suggestion: buy a copy of Cephalopods: Octopuses and Cuttlefishes for the Home Aquarium(amzn/b&n/abe/pwll) by Colin Dunlop and Nancy King. This is essential. All in one place and in a very practical way, it describes all the important information you'll need to successfully keep a cephalopod in your home, and it may discourage all but the most fervent. Here are a few of the reasons you should not try to keep cephalopods, gleaned from this book and my reading of TONMO.

  • They are difficult to raise. You will need a well-maintained salt water aquarium, which with all the apparatus required can be quite expensive, and you will need to invest a fair amount of time every day in maintenance. This is a job for a serious aquarist.

  • They need live foods. What this means for most of us is that you'll need two tanks — one for the octopus and another to raise the octopus's food.

  • A cephalopod's life is one of heart-breaking brevity. They do not live for long, even in the wild, so no matter what, you're going to have a pet funeral every six months to a year.

  • There are few species that you can keep. Most can't live in the confines of a tank, a few are very dangerous, and many are rare, and it would be unethical to strip natural environments of these precious specimens.

  • It will eat just about anything else you try to put in the aquarium. The cephalopod and its food will be the only creatures you will have.

  • Forget keeping one as a pet—a cephalopod in the house is your Lord and Master, and you will serve it everyday. Forget those silly ideas that this will be your little pal, it is going to rule you.

If you aren't yet discouraged, then you know your proper place in the universe and can consider getting a cephalopod. In order to figure out how to do so, you will first have to buy this book: it contains all the information you will need to proceed. Plus, it's beautifully illustrated with photographs of the beloved class, so you'll enjoy reading it, and it therefore makes an excellent Squidmas gift. Then what you may do is purchase a salt-water aquarium and supplies, but at first you should only raise something boring, like damselfish. Master the art of maintaining a stable aquarium for at least a year, and then you may consider obtaining a cephalopod for it. Conceivably, then, you could have one for next Squidmas. But don't even dream of it yet.

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The TONMO link isn't working for me.
http://www.tonmo.com/ does work.

But a few words of advice (speaking from experience here) - do NOT add a moray eel to your octopus tank. Morays like their tako (octopus sushi).

I haven't seen you post info about where you'll be drinking on your upcoming visit to Orlando. I do hope I can join you for a pint or two.

This is some pretty good info -- I didn't realize that they were so short-lived. That's a real shame.

But I guess... I wonder what you do if you dream of having tentacles of your /own/? (Maybe cut back on the Japanese animation a bit?)

Zeekster @2: From the sound of this post, he's started without you. (j/k) :)

Seriously though... six months to a year, really? For all cephalopoddies? Bummer.

By speedwell (not verified) on 03 Dec 2008 #permalink

The biggest problem about keeping octopi is that they are the consummate escape artists. They can get out of almost any opening in your tank and therefore, your tank needs to be almost air-tight, no gaps around air hoses or filtration lines. They're also deceptively strong and can open doors, therefore you need to either latch or weight any opening into the tank or they'll be gone again. I have a friend who has an octopus right now and he's got a wire-mesh screen over his tank, then all of his plumbing and lighting on top of the mesh, then bricks on top of that to keep the octopus from getting out.

Unfortunately, once they get out, you can pretty much guarantee they'll die, but they'll probably get to the other end of the house before they do. They can be amazingly fast on land as well as in the water.

As PZ says, don't do it unless you're an expert in both salt-water aquariums and dedicated to keeping your octopi safely inside the aquarium.

As a somewhat experienced reef/marine aquarist, I have considered cephalopods - but even with a few years experience behind me, it still scares the bejezus out of me.

Of course, my wife probably wouldn't appreciate the sudden appearance of YET ANOTHER tank in the house...

I'm definitely picking up the books you recommend....only to look. Must resist....

By Yossarian (not verified) on 03 Dec 2008 #permalink

I've wanted a nice salt water aquarium for many years, but I realized a long time ago that the time to get one was when I could afford a service to maintain it for me.

In the meantime, I like to check out the work of vendors like this:

http://www.reynoldspolymer.com/portfolio.cfm?cat=aquariums

They've built some amazing tanks around the world.

-jcr

By John C. Randolph (not verified) on 03 Dec 2008 #permalink

I'll echo the warning about marine aquaria - we had a 120 gallon reef tank, but gave it up when we had our second child. It's a lot of work to maintain salt water tanks.

By Epinephrine (not verified) on 03 Dec 2008 #permalink

And just in case it affects your drinking decision-making, Friday night from 6pm-10pm is the 2nd Annual Orlando Holiday Brew Fest downtown. $30 entry, but free unlimited samples of over 100 beers from around the world plus foods. more info here

From what I learned from my friends, the cooler the animal, the worse of a pet it will make.

What a cool sugarglider, until you realize they are nocturnal, hyper, stinky, and needy

What a neat lizard, until you discover their tail breaks skin when they hit you with it.

What a cute monkey, until it throws poop at you, bites you and breaks everything it can.

If the animal seems so cool you can understand why you don't often see them as pets, there is most likely a good reason.

I wouldn't dream of going through that much trouble, even though a cuttlefish could take my fancy.

What I am wondering is if the cephalopod market is well-regulated and thus avoids trafficking in endangered species taken from the wild. I'd hate to see cephalopods promoted only to put them into danger.

Do they breed reasonably well in captivity?

Glen D
http://tinyurl.com/2kxyc7

knew a fella years ago who had a beauutiful saltwater tank. Wifey got him the cutest little octopus. Several days later he had a big, single occupant, saltwater tank.

I've actually saw a Hapalochlaena lunulata in a pet store once. I've often wondered if some loon actually purchased it and tried to had feed it.

I have run a temperate marine aquarium for several years now and have always wanted to keep an octopus but have decided against it for the very reasons PZ mentions. His advice is not exaggerated.

If you absolutely have to have one why not knit it? Those are nautloids, but there are several free knit/crochet patterns for squid and octopus; Google can help you find them.

Kept a marine tank for a few years, with indifferent success. Finally gave it up as too much work. For that matter, we eventually gave up on freshwater tanks as well (and we used to have half-a-dozen). Now we just keep koi and GF in a couple of outdoor ponds. Much easier -- almost self-maintaining (I think it's something about the water:plant:fish ratio being much higher on the first two numbers).

Just buy triops, folks. They're bloody cannibals and you won't weep for them!

"You will need a well-maintained salt water aquarium[...]"
This raises an interesting question that had never occurred to me before - why do there seem to be no freshwater octopodes or squid or other cephalopods? What's missing from the freshwater environment that make it an unattractive evolutionary niche for cephalopods?

I was once going to try my hand at the ol'aquarium thing. Got a deal on the tank - a 20 gallon hexagon for like $50.00 or so. Only later - before any fish was bought - did I find out that such tanks are considered Fish Death Traps. It is now a nice terrarium. Mostly ferns.

By LibraryGuy (not verified) on 03 Dec 2008 #permalink

Wow, this exactly the post I've wanted after reading all the cephalopod updates. Just the other day I commented to my girlfriend that they would be unusual pets (I've never known anyone to have one). I was already discouraged because of price and my apartment's inconsistent heating, but the 6-12 month life, high maintenance, and other factors make it a definite "no".

Maybe I'll go for a corn snake instead. Finding a good heat lamp is no problem, so if I can locate a supplier of mice, it wouldn't be too bad. Once the snakes are a decent size you don't have to feed them too often. Or maybe I'll just get a stupid goldfish...

@ the escaping comment:

A strip of AstroTurf around the rim of the tank works quite well for keeping them in. They hate the feel of it.

Eamon, my success came when I started performing regular water changes every single week. I live in Cape Town South Africa and can get natural sea water from the Two Oceans Aquarium in the waterfront. The reward has been amazing, life has exploded in my tank since doing that. All it takes is commitment, time, passion, money, your house, your soul, your wife ...

well, I for one, welcome our new tentacled overlords

wait...
...what was the question ?

I am an experienced saltwater fish guy and I won't touch them with a 50 foot pole. I have owned a shark, lionfish, scorpionfish, eels, triggers, and the creme de la creme was a stonefish. Now I live about 5 hours from the coast in Texas, the chances of a local ER having stonefish anti-venom is very, very, very, very slim.

One thing I didn't see is about how Octopi like to get out of the tank and go explore. I have kept many eels that do this as well. From what I understand you actually have to duct tape up even the smallest of holes in the tank because they WILL find a way to get out.

I also read a story about a woman who kept a couple. She had a tank in the kitchen and when her's was ready to eat he would actually pull the magnet cleaner off the tank so it would drop the other side onto the tile and make noise. They are VERY smart and from what I hear are on par with very smart dogs.

Also STAY AWAY FROM THE BLUE RINGS!!!!!!!!!!!!!!!! I can not stress this enough!!!!!! I have seen way too many stupid ass people buy these thinks as pets knowing full well that they can kill you. Not only are they great hiders but they are much quicker than you and sometimes the bite is painless. If you do not seek medical attention AS SOON AS you are bitten you will die, period.

Glen D: Absolutelyvthere are some reputable captive breeders. Tonmo would be your best bet to find them.

PZ's post describes me, and my experience, to a T. It took me a long time to be confident I could adopt a ceph master, and it's the antithesis of the casual pet. But if you're truly odd enough to want it, it's feasible.

I lost mine in a tragic accident wherein a tank electrical safety system shut the whole thing down for too long (he suffocated) and I haven't gotten another, since I'm now waiting until my budget allows me to create a specially customized tank. But some additional caveats I would add:

--If your tank is well-designed, you will ironically rarely see your ceph. They nearly always hide.
--Many cephs are very temperature sensitive. A heater or chiller will make your system much more expensive to own and maintain.
--they really will eat everything...except most echinoderms. Blue tux urchins and brittle stars seem to be safe.

I'm sure the books PZ cites cover this stuff as well.

First seashorses, now this: all my acquarium dreams ended. At least I have had success with small parrots, which have never tried to kill me.

By Leslie in Canada (not verified) on 03 Dec 2008 #permalink

This thread is full of naysayers. Of course the octopus can be trained to eat dead things such as thawed krill, clam, squid and fish. Plus, they know their limits on what they can eat and many larger, peaceful fish make excellent tank mates, as do most coral and anemones.

In my experience with octopuses working at a saltwater specialty store is that most people don't realize nocturnal animals are...well, nocturnal, how big they grow (which is why the blue ring is popular due to its small size) and that their beak is the limiting factor on the size of hole they can squeeze through.

For some reason I used to have dreams about having an aquarium with tiny cuttlefish for years. Since my subconscious seemed to think it was such a good idea, I decided to see what the Internet had to say and was heartbroken to find that keeping a cephalopod in an aquarium was way beyond my abilities.

Thank goodness there's always cats...

By Sclerophanax (not verified) on 03 Dec 2008 #permalink

When I had one I caught in Hawaii a long time ago it got out the 55 gal tank (natural sea water) it was in and started trucking across the lawn (towards the beach a block away). But the house cats had it surrounded in the morning and I guess it expired there on the lawn. But hey, your mileage may vary.

just go and get some sea monkeys.

i remember in the old adds they had tridents and crowns--hmm, they don't sound to peacefull...

i suppose if they get uppity you can feed 'em to your zebra fish.

What's missing from the freshwater environment that make it an unattractive evolutionary niche for cephalopods?

hmmm...
Salt?

Sorry. It's almost certainly a physiological, rather than an ecological barrier. Probably a better question is why are there freshwater mollusks (bivalves & gastropods)? They survive with extremely dilute body fluids, and my guess would be that the active lifestyle of cephalopods (neuron function? muscle function?) is not compatible with such dilution. But it's a guess.

By Sven DiMilo (not verified) on 03 Dec 2008 #permalink

I decided to see what the Internet had to say and was heartbroken to find that keeping a cephalopod in an aquarium was way beyond my abilities.

Thank goodness there's always cats...

It's a lot of work to keep cats in an aquarium too. Little bastards keep scratching and biting when I try to put 'em in and even when I finally manage it, they don't last shit time.

"slowly wading through the meadows of brit, the Pequod still held on her way north-eastward towards the island of Java; a gentle air impelling her keel, so that in the surrounding serenity her three tall tapering masts mildly waved to that languid breeze, as three mild palms on a plain. And still, at wide intervals in the silvery night, the lonely, alluring jet would be seen.

But one transparent blue morning, when a stillness almost preternatural spread over the sea, however unattended with any stagnant calm; when the long burnished sun-glade on the waters seemed a golden finger laid across them, enjoining some secrecy; when the slippered waves whispered together as they softly ran on; in this profound hush of the visible sphere a strange spectre was seen by Daggoo from the main-mast-head.

In the distance, a great white mass lazily rose, and rising higher and higher, and disentangling itself from the azure, at last gleamed before our prow like a snow-slide, new slid from the hills. Thus glistening for a moment, as slowly it subsided, and sank. Then once more arose, and silently gleamed. It seemed not a whale; and yet is this Moby Dick? thought Daggoo. Again the phantom went down, but on re-appearing once more, with a stiletto-like cry that startled every man from his nod, the negro yelled out- "There! there again! there she breaches! right ahead! The White Whale, the White Whale!"

Upon this, the seamen rushed to the yard-arms, as in swarming-time the bees rush to the boughs. Bare-headed in the sultry sun, Ahab stood on the bowsprit, and with one hand pushed far behind in readiness to wave his orders to the helmsman, cast his eager glance in the direction indicated aloft by the outstretched motionless arm of Daggoo.

Whether the flitting attendance of the one still and solitary jet had gradually worked upon Ahab, so that he was now prepared to connect the ideas of mildness and repose with the first sight of the particular whale he pursued; however this was, or whether his eagerness betrayed him; whichever way it might have been, no sooner did he distinctly perceive the white mass, than with a quick intensity he instantly gave orders for lowering.

The four boats were soon on the water; Ahab's in advance, and all swiftly pulling towards their prey. Soon it went down, and while, with oars suspended, we were awaiting its reappearance, lo! in the same spot where it sank, once more it slowly rose. Almost forgetting for the moment all thoughts of Moby Dick, we now gazed at the most wondrous phenomenon which the secret seas have hitherto revealed to mankind. A vast pulpy mass, furlongs in length and breadth, of a glancing cream-color, lay floating on the water, innumerable long arms radiating from its centre, and curling and twisting like a nest of anacondas, as if blindly to catch at any hapless object within reach. No perceptible face or front did it have; no conceivable token of either sensation or instinct; but undulated there on the billows, an unearthly, formless, chance-like apparition of life.

As with a low sucking sound it slowly disappeared again, Starbuck still gazing at the agitated waters where it had sunk, with a wild voice exclaimed- "Almost rather had I seen Moby Dick and fought him, than to have seen thee, thou white ghost!"

"What was it, Sir?" said Flask.

"The great live squid, which, they say, few whale-ships ever beheld, and returned to their ports to tell of it."

But Ahab said nothing; turning his boat, he sailed back to the vessel; the rest as silently following.

Whatever superstitions the sperm whalemen in general have connected with the sight of this object, certain it is, that a glimpse of it being so very unusual, that circumstance has gone far to invest it with portentousness. So rarely is it beheld, that though one and all of them declare it to be the largest animated thing in the ocean, yet very few of them have any but the most vague ideas concerning its true nature and form; notwithstanding, they believe it to furnish to the sperm whale his only food. For though other species of whales find their food above water, and may be seen by man in the act of feeding, the spermaceti whale obtains his whole food in unknown zones below the surface; and only by inference is it that any one can tell of what, precisely, that food consists. At times, when closely pursued, he will disgorge what are supposed to be the detached arms of the squid; some of them thus exhibited exceeding twenty and thirty feet in length. They fancy that the monster to which these arms belonged ordinarily clings by them to the bed of the ocean; and that the sperm whale, unlike other species, is supplied with teeth in order to attack and tear it.

There seems some ground to imagine that the great Kraken of Bishop Pontoppodan may ultimately resolve itself into Squid. The manner in which the Bishop describes it, as alternately rising and sinking, with some other particulars he narrates, in all this the two correspond. But much abatement is necessary with respect to the incredible bulk he assigns it.

By some naturalists who have vaguely heard rumors of the mysterious creature, here spoken of, it is included among the class of cuttle-fish, to which, indeed, in certain external respects it would seem to belong, but only as the Anak of the tribe."

By The Great Spirit (not verified) on 03 Dec 2008 #permalink

It's a lot of work to keep cats in an aquarium too.

It gets a lot easier once you remove the water. From the aquarium that is, not the cats.

By Sclerophanax (not verified) on 03 Dec 2008 #permalink

Why not learn to dive and see them in the wild instead? I've seen a few whilst diving and, provided you're properly respectful and lucky, occasionally their curiousity will lead them to 'play' with you. They seem to be rather like cats with a stranger in that regard, they either take to you or they're off without a backward glance.

If they're not in a playful mood and you keep your distance without harassing them you will occasionally get wonderful camouflage displays.

Endearing creatures, a treat to encounter underwater.

It gets a lot easier once you remove the water.

I suspected I was doing something wrong: the problem was independent of water temperature and salinity.

Emmet Caulfield @ #35

Actually, cats make great fish. Legs off, fins on. Pipe through the back of the neck so they can breath.

It gets a lot easier once you remove the water. From the aquarium that is, not the cats.

They do keep longer when freeze dried. Though usually less active.

Hmm...

I don't think I'd want an octo for a pet, b/c I can barely hardy plants alive...

BUT, i would like to take this opportunity to call attention to a Cartoon Network show (found it on DVD) called Squidbillies.

You see, it is about a Squid, who is a Hillbilly. Totally anti-religious (Jesus is also a squid, and seems to like to get it on with the gramma), anti-racist ect...

Something worth checking out

Sven DiMilo: Either way of phrasing the question works - it was because I know that other molluscs obviously found their way into freshwater that I was so curious why cephalopods missed out.

Are there any that either live or "survive" (i.e. can adapt for short periods of time) in brackish water, I wonder...

looks like someone is anti-pharyngulating this poll... lots of No votes all of a sudden

I've kept an aquarium for four years now, and after losing the last of my pond cows (C. auratus) to dropsy I took advantage of the opportunity to move to a planted tank. No 'podes of course, but a swarm of neon tetras and white clouds, plus one albino pleco and a pygmy puffer. (I bought the puffer on the advice of the store personnel who said it'd get rid of the snails and play peacefully with everyone else, but teh intertubes say different. So far he's a little too small to bother the other fish, though the snail population has plummeted.)

Having also kept cats in the past, I do not recommend them for the planted or otherwise aquascaped aquarium, due to their tendency to dig. They're also less than ideal for the unplanted aquarium, due to their tendency to breathe. If you simply must keep an aquarium cat, consider a terrarium/aquarium setup with at least three inches of dry sand for digging, and at least a third of the top of the tank should be open air to allow for sufficient gas exchange. Unscrupulous pet stores will tell you that it doesn't matter, but short-haired breeds fare the best, what with the longer-haired varieties being generally poor swimmers and the no-hair varieties prone to catching the shivers unless the tank is well heated.

If you've got the space, you may try to keep the one breed of water-loving cat P. tigris in a larger outdoor pond (with moats and fences to prevent escape), but ensure you've got access to reliable sources of live and frozen food such as daphnia, brine shrimp, and Manchurian elk.

By Brownian, OM (not verified) on 03 Dec 2008 #permalink

I managed to keep a few octopuses happy for several months in aquaria with little trouble...at a marine lab that had an open seawater system with spigots providing fresh, cold, well-oxygenated seawater. Oh, and you need to be willing to go hunting for live crustaceans for octopus food on a regular basis. Yes, you can train them to take some non-living food (they'll even eat crayfish, if that's all you've got), but if you're going to bother keeping an octopus, wouldn't you want to keep it happy? And if you forget to cover your tank with a weighed or locked cover even once, they will go over the side.

Other reasons not to keep octopuses -- they like lots of oxygen, they appear to be sensitive to trace metal concentrations and if you upset them, they will ink, which is not something you really want happening in a closed seawater system.

And don't even bother trying to maintain most squid in aquaria -- the pros (e.g., the Monterey Bay Aquarium) have problems with them, even in very large, relatively squid-friendly tanks. Some cuttles and sepiolids aren't too bad, though.

Forget keeping one as a pet--a cephalopod in the house is your Lord and Master, and you will serve it everyday. Forget those silly ideas that this will be your little pal, it is going to rule you.

So ... cephalopods are the cats of the ocean.

Thanks, PZ, for using your bully pulpit for this worthy cause.

Remember, folks: an octopus is for life, not just for Squidmas.

No 'podes of course, but a swarm of neon tetras and white clouds, plus one albino pleco and a pygmy puffer.

Oh! Do you know what species?

windy:

It was sold as a 'Pea' Puffer, so that would be Carinotetraodon travancoricus, I think. It's seriously way too cute for me to handle, with its little tadpole body and tendency to drift about in a haphazard way with its little eyes darting about, as if it's trying to remain nonchalant while sizing everything and everybody else up. You can almost see him trying to whistle with his hands in his pockets.

Everything I've read about them suggests they like to nip the fins of slower long-finned species, so I'm watching the tetras and minnows closely and hoping that they're too quick and short-finned to be harassed. I've read that ideally, they're best kept in a single-species tank with no more than one male, so prepare for that if you decide to get one (some aquarists have reported keeping them with Otocinclus catfish with no trouble).

Meanwhile, if anything goes wrong in my tank I'll have to chalk it up to a poorly-researched impulse-buy on my part.

By Brownian, OM (not verified) on 03 Dec 2008 #permalink

This thread reminds me of Lucky Star 18.

By Anonymous Coward (not verified) on 03 Dec 2008 #permalink

I think it'd be really cool to have an octopus in the home... And I'm not gonna do it.

Here's why...

We just got a 10-gallon aquarium. Filter, the right food, the right temp, and so on. And I still killed my kids' 4 tiny goldfish.

That, and I don't want to endanger our 2,000 watt spotlight in the kitchen.

Or our cockatiel.

(I have to be the lamest daddy in the world. D'oh, I still can't figure out what I did wrong. I suspect overfeeding and a nitrogen buildup, though.)

My parents had a big aquarium before I was born - absolutely no recollection of it, myself, but that's not surprising. I can't tell you what happened when I was ten, much much less what I may or may not have seen before the age of four. Prolly not saltwater, though.

Anyway, 'pods don't pur, and I'dn't like to roll over and sleep on the wet spot, anyway.

As for you people trying to keep cats in aquaria, it sounds like you've been skimping on accessories.

Sven DiMilo #34:

I'm still puzzled by that explanation. After all, there are terrestrial gastropods, so it would seem that maintaining electrolyte balance in an even more challenging environment than fresh water is not an insurmountable barrier for molluscan physiology.

And why should molluscs be particularly vulnerable in this regard, or need to have dilute body fluids to make the transition to fresh water? It didn't seem to have been a problem for the equally active, neurologically complex chordates, for example.

It was sold as a 'Pea' Puffer, so that would be Carinotetraodon travancoricus, I think.

That's what I used to have! Although I'm not 100% sure that there wasn't a C. imitator in the bunch. Yes, they are too cute.

You said that your fish is "so far" too small, but unless your fish is under 1 cm head to tail it's probably adult size!

I've read that ideally, they're best kept in a single-species tank with no more than one male, so prepare for that if you decide to get one

Yes, I had 1 male (sometimes did the ridge display thing), 1 female and 1 sexually ambiguous one that got picked on by the male despite being the biggest. And they kept bothering the bristlenoses but couldn't do much damage.

Thanks, windy. I admit I have no idea which species of Carinotetraodon it really is, but whichever it is it seems to be a lot better natured than what I've been led to expect.

It is just under 1 cm in size, so I imagine it'll grow a little bigger, and I hope it doesn't turn more aggressive then.

The bigger problem is explaining to guests that yes, it's a puffer, but no, I've never seen it puff up and I expect I never will.

By Brownian, OM (not verified) on 03 Dec 2008 #permalink

the kids have all moved out, so you're thinking having a little intelligent life at home would be nice. Or maybe you're kids are still home, and you think they'd love a pretty pet

What happened to option 3): The kids are still in the house, so you're thinking having a little intelligent life at home would be nice.

there are terrestrial gastropods, so it would seem that maintaining electrolyte balance in an even more challenging environment than fresh water is not an insurmountable barrier for molluscan physiology. And why should molluscs be particularly vulnerable in this regard, or need to have dilute body fluids to make the transition to fresh water? It didn't seem to have been a problem for the equally active, neurologically complex chordates, for example.

Good questions! Don't get me started on comparative osmoregulation or I'll never get home tonight...but just a couple of ideas, skipping all the fascinating caveats and exceptions:
Seawater's total solute composition is about 1000 milliosmoles/liter (mOsm). Nearly all marine invertebrates, including all mollusks, are osmoconformers, with body fluids matching seawater, so within a few percent of 1000 mOsm. Freshwater mollusks have body fluids of like 40-100, among the most dilute large animals there are (similar to freshwater jellyfish). While still considerably more concentrated than their freshwater environment (essentially 0-1 mOsm), this is a huge difference from their marine ancestors.
With fishes, everybody's about the same, near 300 mOsm. Marine species a bit higher, maybe 350-400, freshwater species a bit lower, perhaps 275, but much less variation. Point is that fish are osmoregulating--maintaining body fluid concentrations very different from their environment--no matter where they live. (Interesting cases are the catadromous and anadromous fish that switch from marine to freshwater or vice versa; they switch from pumping extra salt out to pumping scarce salt in).
So for whatever reason, mollusks cannot seem to osmoregulate very well. They have invaded freshwater through tolerance of dilute fluids rather than using energy to keep them highly concentrated (as do freshwater fish). A fish's nervous and muscular systems can work about the same in fresh or sea water because the fish works hard to regulate its body fluids. So if mollusks can't do that, my speculation is that cephalopods can't tolerate dilution of their internal fluids.
But I'm just waving my arms around at this point.

By Sven DiMilo (not verified) on 03 Dec 2008 #permalink

Cool--I'd never heard of freshwater puffers. Good example of how it's not (apparently) that hard for fish to move evolutionarily between seawater and freshwater.

By Sven DiMilo (not verified) on 03 Dec 2008 #permalink

Hi,

I'm one of the authors of the recommended book.

We tried to put many cautions in our book, and octopus keeping is demanding and expensive (after all, they love crabs and shrimp!) That said, we have many people on TONMO.com who are successfully keeping octopuses and cuttlefish.

Taking care of an intellgent marine creature that will interact with you is quite an experience. You get very attached to them, so the short lifespan is a downside.

Hope you like our book!

Nancy

@53

Four goldfish in a ten gallon tank is about three goldfish too many. They produce like ten times the nitrogenous waste of tropicals.

The bigger problem is explaining to guests that yes, it's a puffer, but no, I've never seen it puff up and I expect I never will.

I did see that once. My problem was that people kept insisting that I actually had brackish water puffers, since "there is no such thing as a freshwater puffer" :)

The bigger problem is explaining to guests that yes, it's a puffer, but no, I've never seen it puff up and I expect I never will.
I did see that once. My problem was that people kept insisting that I actually had brackish water puffers, since "there is no such thing as a freshwater puffer" :)

A puffed puffer is a stressed and unhappy puffer, in the exact same way a wailing human is a stressed and unhappy human...

Having said that, does anyone know about the ability of nautiluses to survive in a home aquarium?

Awwwww man... I want to set up a tank so much...

The itch is getting to me again and I've already begun lurking aquarist forums. But, it looks like it'll be a little while before I'm settled enough to be able to dive back in. Can't really set up a tank when I'll be moving in about 16 months. Maybe someday I'll be able to give a cuttle a try, but I'll be happy to just get a couple good sized tanks up and prospering in a couple of years.

Oh, and to Mike M and anyone else new to fishkeeping, the piece of advice you'll likely hear most often is buy the biggest tank you can afford. That, or understock the one you have at first. Until you get the knack/art/routine/habit of maintaining water quality down, a bigger tank is your best friend and best guarantor of success. More water per critter gives you a buffer and extra time to make a water change or whatever you need to do before they start snuffing it.

One of Jacques Cousteau's books had an amusing account of their first attempt at keeping Octos for study onboard the Calypso. Why the tanks were always empty the next morning was a mystery until a crew member caught an octopus in the act of crawling across the deck and over the side of the ship in it's quest for freedom.

A puffed puffer is a stressed and unhappy puffer, in the exact same way a wailing human is a stressed and unhappy human...

A better analogy might be a human that has crapped his pants in shock.

Glen D

Several Tonmo members have successfully bred certain species of octopus,bimacs and mercs primarily, and others have successfully bred sepia bandensis. Join us on Tonmo and you can monitor who's doing what. We recommend that you try to buy captive bred for multiple reasons, but from the point of view of longevity, you are better off doing that because you will know exactly how old your ceph is. When you buy one from an LFS it could already be nearing senescence. Kind of a bummer to spend all that money and have the little thing die of old age 2 weeks after you got it home.

Stanton,

One of our Tonmo members recently got her doctorate from her research on nautilus. They are extremely difficult to keep, and your aquarium would have to be huge. If you are interested, log onto Tonmo and find the posts by Robyn.

Re the question about rare species. Unfortunately, divers who collect in the wild are not always even remotely concerned about preservation of rare, threatened, or endangered species. Certain species should never be kept in a home aquarium but LFS owners are frequently not knowledgeable enough to know what they have received in shipments from wholesalers. We had one young teen asking us for an id of the octopus he had just gotten, he had been hand feeding it and was delighted with it. It was a Hapalochlaena lunulata. The kid had no idea what he had or how dangerous it could be, but when he found out he did the responsible thing, told his mother, who called the LFS. They came out right away and took the octopus back to the store in the tank it was in and fully refunded the boy's money. They were absolutely clueless, had no idea there were poisonous octopus, and were shaken that they could have inadvertently killed a boy or even one of their own employees.

You can learn a great deal about keeping cephs by buying Nancy and Colin's book. I highly recommend it. I also recommend joining us on Tonmo, not just for the ceph keeping information but because we, like all of you, are crazy about cephalopods.

Thanks for the information, Sharon.

I was just wondering, as this one company, Aquatic Connections, used to sell both nautilii and blue ringed octopi (checking their website now, they don't, anymore).

Unfortunately, pet cephalopods are a big no for another reason -- they're almost entirely cyanide-captured for the aquarium trade. Which means that even if you get a non-endangered, healthy, non-blue-ringed pet, you are probably poisoning the ocean, killing a lot of innocent bycatch and subjecting the animal to incredibly undue stress. I love octopodes just as much as the next person, but sometimes a pet just ain't worth it.

But, hey, I'll take a taipan any day.

They were absolutely clueless, had no idea there were poisonous octopus

I may be misremembering, but aren't there lots more poisonous octopus species? It's just that for most of them, the poison is not strong enough to affect humans more than a bee-sting's worth.

By Owlmirror (not verified) on 04 Dec 2008 #permalink