Ok, ok, it’s really more about my busy lifestyle. I’ve no time for a proper post today (I’ve got a Hindi exam tonight, and a pharmacology exam to study for,) so I thought I’d at least bring you some ceph-related Monday reading. There’s a bunch of cephalopod-ey topics getting talked about on the web these days:
“I pleaded not guilty, of course,” Graves said. “I’m going to fight for this tradition. And so, I have to come back in July for a trial, and I’ll be lawyered up.”
(As an aside, can you guess what fans of the San Jose Sharks throw on the ice? You guessed it.)
A lot of the recent interest in cephalopods is due to their skin; the US military (naturally) would love to figure out how to mimic its ability to change color at will. Towards this end, they’ve given a $6 million dollar grant to a group of researchers (including Roger Hanlon, a long-time cephalopod researcher) to figure out how cephalopods work their color-changing magic and then figure out how to mimic it. Besides the obvious military applications, though, there are other possible spin-offs, Hanlon said in an interview
“Some (of the applications) are as simple as heating and cooling things by absorbing or reflecting radiation,” he said. “Detroit can make cars that change color; fashion designers can make dresses that change pattern — highlight of the cocktail party!”
Shallow-water octopuses are generalist predators – this means that they can eat a variety of other animals – and good ones too. They have a few different hunting strategies, with the commonest ones involving the octopus groping along the reef, feeling for food with its arms (although octopuses have been reported to hunt by ambushing (pdf link) as well, striking their prey after spotting it.) You can see the groping strategy at work in this video:
It is clear from previous research that octopus arms are capable of movement, even relatively complex movements, on their own. Thus, when an octopus gropes its way around a reef, it might be that it’s central nervous system is doing very little to control its arms; rather, it seems likely that they move mostly “on their own”. Tamar Gutnick and her colleagues at the Hebrew University of Jerusalem recently published a study that investigated if and how octopuses (of the species Octopus vulgaris) can use information from their central nervous systems to control the movement of a single arm. I’ll let them tell you about it:
(By the way, I love video abstracts/experiments. Thanks, guys!)
The researchers took 7 octopuses and trained them to reach into a clear plastic “maze” where they could choose to put their arm into one of three areas. One of the arms of the maze had a piece of food in it. Since they were only given one chance in each session – if they chose the wrong arm in a session, they weren’t allowed to try again – the octopuses learned to find the food by looking at it through the clear walls of the maze and then make the appropriate arm movements to get it. After the researchers covered the clear maze with masking tape, the octopuses, who could no longer see the food, weren’t able to do the task any more – they got about 1 in 3 trials right, exactly what you’d expect if they were choosing randomly.
The results of this study tell us that octopuses can use visual information to direct the movements of their arms, and that they seem to get more accurate with practice. What we don’t know, however, is how an octopus’s brain could pull this off. It’s clear that simple movements are controlled within the arms themselves, as a disembodied octopus arm can make some movements by itself, but it’s unclear how the “higher-up” parts of the brain that receive visual information from the eyes could mix it with tactile information from the arm to direct these sorts of movements.
The skeptic in me says that there might not be much to be excited about. After all, we’ve known that that octopuses use their vision to do things like find their way around, and size up potential food/predators for a long time. The procedure used, even if it’s new, is sort of limited; it’s essentially a simple detour task, where the animal can see its reward but has to take a complicated route to get to it. As Zen Faulkes pointed out in his post on this study, (which is so cleverly titled as to put me to shame), the octopuses weren’t even very good at learning such an apparently simple task. Compare this to the scores of learning tasks that other laboratory animals like rats (and people, for that matter) whiz through, and it seems like a small step. Some experiments using tasks like this fail while others succeed, and there’s no clear consensus as to how and why octopuses learn (or fail to learn) in certain situations, making it even harder to say anything about how octopuses learn.
Nevertheless, there’s some room to be excited; it’s a small step into an mostly unexplored field. Think about just how foreign an experience this was for the octopuses in the experiment – not over the time scale of the experiment, but over evolutionary time. For millions of years, the ancestors of this species have been hunting on the seafloor in shallow waters, where it’s very unlikely that they’d ever encounter a hard, transparent surface that they might have to move around to get food. Even still, when they’re presented with such a situation, they can navigate it, even if they do it with some difficulty. The behavior of these octopuses, then, seems to me to have evolved not only to work well in a specific situation, but to work (at least minimally) in a wide range of situations – their behavior has evolved to be somewhat flexible. In fact, this is a strategy that is used by all animals that can learn (which seems to be most of them) that helps them deal with the fact that there is no such thing as a perfectly stable and predictable environment, and that behavior needs to adapt to deal with this. For example, your ancestors (if you were an octopus) might have fed on a few specific species of crab for the past few hundred years – if something about the environment changes, you need to be able to learn to hunt something else, or you (and your species) are doomed. Looking at it in this light, it’s not very surprising that a laboratory filled with mazes and puzzles built by scientists would push the limits of a cephalopod’s behavioral flexibility – this is a huge change from the environment the animal evolved in. To quote Zen Faulkes, “the point is not that the animals are slow to learn; the point is that they can learn to do this at all.”
This research is also exciting because it begs questions about how the nervous system of the octopus can do this task. In more familiar research animals (that is, mammals), we know that specific parts of the brain (areas of the motor cortex) control the contraction of specific muscles. Besides this, we’ve identified a whole host of brain structures that play various roles in putting together these movements and in using information from the muscles, skin, and eyes to control and refine them. In mammals, both motor and sensory systems are put together in a such a way that their arrangement in the brain corresponds to their arrangement in the body – this is called somatotopy. (Check out this neat little demonstration of the concept by Jaakko Hakulinen.)
According to another study published in 2009 by researchers from the same university, this doesn’t appear to be the case with the octopus. The investigators in that study couldn’t find any clear relationship between activity in different parts of the octopuses’ brain and different movements. While we know where the information from the eyes goes in the octopus brain (to the sensibly named “visual lobes”,) it’s unclear where it goes from there or how it might interact with the neurons that control the arms, or how this information might be put together with sensory information from the arms. How exactly an octopus’s brain uses vision to control ongoing movements, then, is the most exciting kind of scientific problem: an unsolved one.
Thanks for reading!
Zullo, L., Sumbre, G., Agnisola, C., Flash, T., & Hochner, B. (2009). Nonsomatotopic Organization of the Higher Motor Centers in Octopus Current Biology, 19 (19), 1632-1636 DOI: 10.1016/j.cub.2009.07.067
Gutnick T, Byrne RA, Hochner B, & Kuba M (2011). Octopus vulgaris Uses Visual Information to Determine the Location of Its Arm. Current biology : CB, 21 (6), 460-2 PMID: 21396818
While I was reading Zooborns the other day, I came across this wonderful video of a mother Octopus vulgaris (common octopus) at the California Academy of Sciences hatching her eggs in captivity – she rubs them with an arm and a cloud of baby octopuses explode from the egg cluster!
Breeding is at once exciting and depressing in octopuses. With many species of octopus, they die after they breed. They’ll stop eating in order to tend the eggs, and die shortly thereafter. In addition, the young prove to be very difficult to rear. The young of so-called “small-egged” octopuses initially float freely in the water (they are planktonic at this point) and then settle down onto the floor of the ocean when they get a bit bigger – it’s not known how they should be fed while they are in the planktonic phase, or how to accomodate their “settling out” of the water. Who knows, though – the Steinhart Aquarium was the first facility to successfully breed dwarf cuttlefish in captivity (click through for lots of great cuttlefish photos.) These octopuses are more of a challenge, though; only time will tell, and it’s probably not realistic to be very optimistic.
Cephalopods have a lot to offer – tentacles, beaks, and big scary (and perhaps cute) eyeballs. Today, though, let’s look at a part of the cephalopod body that doesn’t get paid so much attention to, especially by us neurobiologist types: the ink.
Fossil squid with preserved ink sac. Ink sacs are often easily visable in coleoid cephalopod fossils. (via Maitri on Flickr - click through for original.)
Most coleoid cephalopods (that is, all the living cephalopods excluding nautiluses and a few deep-water octopuses) produce ink. This ink is composed chiefly of melanin, which is a dark brown pigment that is found throughout the animal kingdom. Humans have used cephalopod ink for a variety of purposes, including writing, drawing, dying, and cooking (the fact that both a dark brown color of ink and a genus of cuttlefish are both named Sepia is not coincidence.) In fact, you can buy tubs of cephalopod ink online.
Cephalopods use their ink for a different purpose, though; it helps them get away from sticky situations. When severely startled, cephalopods will release ink from their ink sac, which is pushed out of their funnel with a jet of water (which usually also jets the cephalopod in the opposite direction away from the perceved danger.) The resulting cloud of ink could serve many functions; it could conceal the escaping cephalopod’s location from the predator, serve as a false target for the predator (who would attack the dark ink instead of pursuing its prey,) frighten the predator, or even trick the predator’s sensory systems into thinking it had already caught something (I’ll explain this last one at the end of the post.)
One neat property of cephalopod ink, though, has nothing to do with how predators perceive it, but rather how cephalopods perceive it.
When one squid in a shoal inks (“inking” being the action of expelling ink into the water) the rest of the shoal can certainly see what has happened and be alerted to the immanent danger that way. In addition to this, though, it has been hypothesized that squid can chemically sense the ink in the water, which would give them another way to keep abreast of squid-predator interactions going on around them.
One study that found evidence for this hypothesis (which is actually a part of a series of studies in this line of research) was done by Gilly and Lucero (1991) at Hopkins Marine Station in California. These investigators restrained squid (loligo opalescens) by attaching their dorsal mantle to a platform with cyanoacrylate glue (the same stuff that Super Glue is made of,) and then used a pipette to place small amounts of various substances onto a chemoreceptive organ located behind the squid’s eye.
Photograph and photomicrograph of squid olfactory organ - from Gilly and Lucero (1992)
They recorded the activity of the squid with a video camera, and everything was done remotely, so that the movement of the experimenter’s would not upset the squid and cause extra escape-like behavior. Escape-like behavior was measured in terms of the pressure inside the squid’s mantle, which was recorded via a tiny pressure transducer inserted inside the squid’s mantle. One of their records is shown here – the spikes in pressure reflect jets of water being expelled from the squid’s mantle, as it presumably attempts to escape from the chemical stimuli that signal some sort of danger in the environment.
They found that pipetting ink from an animal of the same species of the test animal onto the olfactory organ caused jetting. Furthermore, they found that a specific component of squid ink, L-DOPA (which is a precursor of melanin, the main pigment in squid ink) caused jetting just as much as did whole ink. On this basis, the authors concluded that L-DOPA is used as a sort of chemical alarm signal between L. opalescens individuals. (I should note that some of the authors cited in this post write that squid ink is actually a cue, not a signal, as a signal results in an action on the part of the receiver that benefits both the receiver and the sender of the signal. Escape responses by squid in response to the ink of conspecifics do not fit this definition.)
A more recent study by Wood, Pennoyer, and Derby (2008) looked at the responses of Caribbean reef squid (Sepioteuthis sepioidea) to squid ink preparations. This species of squid has ink that hangs together in a mucous-ey glob in the water, forming what the authors call a “psuedomorph”, or false animal shape that confuses predators.
Each squid was tested by placing a small amount of an ink preparation into its aquarium and videotaping its behavior during and after this event. The authors used a scoring system to determine how defensively each squid behaved during each test, with points on a scale of defensiveness being awarded for behaviors like jetting, specific postures that are used to hide from predators, and certain color changes that are known to signal alarm. A higher score on this measure of defensiveness indicated that the squid was “alarmed” (or something like that) during the test. Below is a video showing on of their tests, produced by New Scientist:
The authors found that S. sepioidea responsed with alarm to fresh squid ink placed in their aquarium. The ink worked to cause alarm responses even after it had been frozen, albeit not as well – the authors noted that it changed in consistency, and dispersed much more quickly. Ink that was placed into an adjacent aquarium (meaning the squid could see it, but could definitely not chemically sense it) worked very well to stimulate escape behavior. This argues that one of the stimuli that this species of squid uses to respond to ink is its appearance. What about chemoreception, though?
The authors produced “melanin-free ink” by centrifuging fresh ink to remove all of the melanin-containing granules in it. They reasoned that this ink was just link the whole ink chemically, except that it did not contain the specific chemical that made it opaque (melanin). They found that the squids did not respond to this ink that they could not see. These results point to the use of vision exclusively in S. sepioidea in responding to other squid’s ink, apparently conclusively.
Frustratingly, they don’t, really. It would be easy enough to chalk this result up to species differences – one species can chemically sense ink, and the other species cannot. These results, however, don’t say enough to make this claim (although there may exist other research that answers this question.)
In a paper by Lucero, Farrington, and Gilly (1994), squid (L. opalescens) ink was analyzed for the presence of L-DOPA and dopamine (they found it, but that’s not the reason I mention it.) They found that, in seawater, L-DOPA and dopamine are rapidly degraded via oxidation reactions, which would certainly dampen any effects they would have on the behavior of squid swimming in that water. They also found that the L-DOPA and dopamine in squid ink did not degrade this rapidly – these preparations behaved as if they were being protected by some sort of antioxidant contained within squid ink. While the authors used ascorbic acid (a small, soluble molecule) to replicate this effect, it’s possible that any anti-oxidant activity in the squid ink is provided by a protein (or another large, centrifuge-seperable molecule.) When Wood et al. prepared their “melanin-free ink”, they may also have removed some component of the ink that is essential for its activity as a chemical signal (for a hypothetical example, a protein that prevents that oxidation of L-DOPA and dopamine in the vicinity of the ink blob.) They may even have done something that eliminated the L-DOPA and dopamine altogether – they provide not chemical analysis of their ink preparations, and so it’s hard to know. The authors acknowledge that this is a shortcoming of their work in their paper, so there’s been no oversight on their part – it just would have been nice if they’d done a bit more in the way of quantifying the chemistry of the preparations they were using. Oh well – it’s something for the next round of studies, I guess.
I mentioned that squid ink might trick predators into “thinking” they had already caught the squid and were eating it, a trick called phagomimicry. This is because squid ink (and the exudates that other molluscs exude under stress) contains, among other things, a full complement of free amino acids – these are chemicals that predators taste when they eat flesh. If a predator gets a mouthful of ink, if they can sense the amino acids that normally tell them that they’re eating flesh, they may behave as if they have already caught and/or eaten their prey, and give up pursuit.
Thanks for reading!
W. F. Gilly and Mary T. Lucero (1992). Behavioral Responses to Chemical Stimulation of the Olfactory Organ of the Squid, Loligo opalescens Journal of Experimental Biology
WOOD, J., PENNOYER, K., & DERBY, C. (2008). Ink is a conspecific alarm cue in the Caribbean reef squid, Sepioteuthis sepioidea Journal of Experimental Marine Biology and Ecology, 367 (1), 11-16 DOI: 10.1016/j.jembe.2008.08.004
Lucero, M., Farrington, H., & Gilly, W. (1994). Quantification of l-Dopa and Dopamine in Squid Ink: Implications for Chemoreception Biological Bulletin, 187 (1) DOI: 10.2307/1542165
I’m back on my mission of keeping you on the cutting edge of cephalopod-related video content online! Today’s selections all feature incirrate octopods, doing what they do best: looking incredibly weird as they slink around. The first two videos (by Tapio Kuiri and Bouju1, respectively) show hunting behavior, with some great interbrachial web shots. The last one, I have no source on, but if you like seeing writhing tentacles set to Chinese (I think) music and narration, it’ll be right up your alley! (If somebody can translate/give some background on the video, we’d all be very appreciative.)
To get things started, here’s a video of an octopus with a Mr. Potato Head Toy (and other things):
You’ll see why this is relevant in a minute. Now on to the post!
“Enrichment” is a psychological term that’s been thrown around a lot. It’s become a buzzword in publications about education, perhaps rightly so given its huge impact on the field of developmental psychology. It has been the subject of intense study in psychology, and continues to be the subject of study. But what exactly is it that we are referring to when we use the term “enrichment”?
Before I get to that, let’s take a step back and consider how brains work. Brains, in the sense that I am talking about, are simply big networks of neurons (there are other types of cells, but we can ignore them for now.) These neurons get sensory input from the body, talk amongst themselves, and send out signals that cause the organism to behave in a certain way. This is, in a nutshell, what brains do – they generate behavior. Importantly, though, they don’t just generate any behavior at a given time; they generate the appropriate behavioral response to the immediate situation. Even more impressively, in some animals, they generate the response that will lead to a positive outcome in some hypothetical future situation (for example, when birds hide food to recover later.) Thus, brains work because they can process incoming sensory information into relevant and adaptive behaviors. Neurons can do this because they are connected to each other in complex but well-controlled and highly-specific ways. Much in the way that an electrical device will only operate if all of its components are connected correctly, brains will only work if all of their neurons (or at least most of them) are “wired” together into functional circuits.
It may come as no surprise, then, that brains only wired the way they are because of the sensory input they receive. During brain development (and, to a lesser extent, throughout life,) neurons require sensory input and behavioral output to form proper connections as well as get rid of improper connections. At the cellular level, this phenomenon is called activity-dependent or experience-dependent plasticity. One can think of it this way: connections between neurons (called synapses) that are used a lot and produce functional behaviors get stronger; that is, they become more efficient and transmit larger signals from neuron to neuron. Synapses that are not used, or that don’t contribute or contribute negatively to the function of a certain circuit become weaker; that is, they become smaller and less efficient, and may even disappear altogether.
This can be demonstrated directly by looking at neurons that process incoming visual information from the eyes. Suppose we were to raise one group of animals (lets say, ferrets) completely in the dark, and another, otherwise identical group of animals normally. Then, we kill both groups of animals and look at the neurons in their visual system (for example, in visual cortex.) The group that was raised under normal light will have, by definition, normal connections between the neurons in the visual system – specifically, these neurons will form functional circuits that allow animals to sense and respond to their environment. In the animals that were reared in the dark (called, sensibly, “dark-reared” animals,) we’ll see a host of abnormalities – cells will have the wrong shapes, end up in the wrong places, and have the wrong connections. Besides this, we could demonstrate some deficiencies in visual perception in the dark-reared animals. Taken together, these results, which have been replicated in a variety of vertebrates, strongly support the idea that sensory systems need input during development in order to develop properly.
It’s a small logical step to tentatively extend the principal of experience-dependent plasticity to brain functions that are more complex than immediate sensory analysis. In the mammalian cortex (which is involved in such complex behaviors as navigation, auditory and visual perception, social behavior, speech, thought, and so forth,) normal development is dependent on the experience of the animal in question during development. The input that these brain areas deal with is almost unthinkably complex. Their function often involves the monitoring the interaction of large parts of the organism with the environment over an extended period of time. For example, cortical areas involved in directing complex hand movements (say, playing a musical instrument) receive their input in the context of a feedback loop that involves planning a movement, executing it, and then determining whether the movement was successful and, if it was not, how it needs to be changed in order to be successful the next time. More abstract cognitive processes become even more complicated, as the brain areas responsible for these have to take into account such complex “stimuli” as the animals current and previous emotional states, inferred emotional states in other animals, the value of various hypothetical outcomes to the organism, prior cognitive states the animal has had, and so forth.
Here’s where the idea of environmental enrichment comes into the picture. The logic goes like this: because neural development is facilitated by the nervous system’s interaction with the environment, and because the more integrative areas of the brain (like the cortex) interact with the environment in very complex ways, normal brain development requires interaction with a very complex environment. If this theory is true, animals raised in very restricted environments (we might call them “environmentally impoverished”) should show maladaptive or sub-normal behavior as adults. In fact, this prediction has been borne out in many studies, which find that (among other things) environmentally impoverished animals (and, although it has been less directly demonstrated, people) have altered learning abilities, exploratory behavior, cognition, stress reactivity, and social behavior.
A corollary of this theory is the idea that nervous systems which have evolved to deal with the environment in very complex ways function abnormally when they do not have complex environments to deal with, much like the way that muscles atrophy if they are not used. Part of successfully engaging a complex environment is continually interacting with and exploring it – indeed, many animals have evolved a propensity to explore and manipulate their environment. Thus, animals with complex behavioral repertoires require complex environments to interact with in order to maintain normal brain function. This theory predicts that a lack of complexity in some animals’ (or people’s) environments should lead to aberrant behavior, and that such behavior can be corrected by providing an appropriately complex environment to those animals (or people.) This prediction is borne out in a variety of studies that show that, in captive adult animals, providing more complex environments leads to lower stress levels, less aggression, and fewer pathological and stereotyped behaviors.
Dr. James Wood’s article, “Environmental Enrichment in the Giant Pacific Octopus; Happy as a clam?” makes the case that aquariums should provide environmental enrichment for captive octopuses. I won’t follow his arguments exactly, but I will examine some of the same questions that he covers, and make reference to and critiques of his work as I find it relevant.
The big question is this: Should we provide environmental enrichment to captive cephalopods? Let me rephrase this: do the benefits of providing environmental enrichment to cephalopods justify the costs incurred by doing so?
First, let’s consider the possible benefits. Anderson and Wood point out several:
1. Captive animals should be kept healthy and allowed to behave normally. Behavioral health is as important to the longevity and quality of animal’s lives as is physiologic health. The real question here is whether cephalopods have complex enough behavior that they might show pathological behavior in response to captive conditions. Put in a more cognitive frame: are cephalopods smart enough to be hurt by captivity and, consequently, to benefit from enrichment?
Indeed, it is hard to tell whether cephalopods could benefit from enrichment. To the question of how we can tell if giant pacific octopuses could benefit from enrichment, Anderson and Wood succinctly conclude: “Simply put, we cannot.” Because cephalopods have evolved under predation from fishes, they reason, they spend most of the time during which they are not hunting hiding in their dens. It’s hard to tell if this is “good” for the octopus (after all, it seems like it would be nice not to have the daily stress of fleeing from predators and risking death during hunting) or bad (because, if cephalopods can become bored, this behavior certainly seems like it would be really boring.) In addition, little is know about how behavioral pathology might look in cephalopods, because we know so little about their behavior in general.
In sum, cephalopods may or may not benefit from enrichment. Given how complex their behavior appears to be, and the likelihood that at least some cephalopods possess cognitive capacities to rival at least some vertebrates, it seems like there’s a reasonably good chance that they could. This isn’t a convincing case in itself – it really depends on the costs of providing enrichment to cephalopods. If the costs are low, this might be enough of a reason to do it; with increasing costs, it becomes an increasingly bad bet.
2. Animal enclosures should meet the expectations of the public. Showing the public what they want to see – which is, it seems, natural-looking enclosures that animals can interact with) will lead to financial success and public support for zoos and aquariums. Researchers, institutions, and the enterprise of biological science in general stand to benefit from the increased public support that comes with presenting a public-pleasing image of animal husbandry in research. Also, if the public sees naturally-behaving animals instead of pathologically-behaving animals, they learn more about the animal’s behavior. A primary function of zoos and aquariums is to educate the public about animals, and so the potential to improve on this education is an important possible result of providing enrichment to cephalopods.
This is an interesting idea to me. Octopuses are popular aquarium animals, but not very popular research animals. The public face of animal research is usually mammalian, including rats, mice, rabbits, and primates. It’s doubtful to me that researchers would benefit from an improved public image if all octopuses used in research were given lots of enrichment. In zoos and aquariums, though, this seems like a valid concern. Indeed, it could offset the monetary costs of providing enrichment for these institutions, which allows less tangible benefits (like the possibility of relieving the suffering of bored octopodes) to be given more weight in deciding whether or not to provide enrichment for captive cephalopods.
3. Finally, zoos and aquariums often care for animals with the goal of eventually releasing them into the wild. Animals whose behavior is dependent on learning need to practice skills that will allow them to succeed, such as hunting, defending from predators and rivals, and maintaining good relationships with other individuals of their species. The Seattle aquarium, for example, does this with their giant pacific octopuses. They catch individuals, hold and display them for a few years, and then release them into the wild so that they have a chance to breed.
It’s doubtful to me that enrichment benefits cephalopods in this way. I can’t say that it’s impossible, but it seems unlikely. While cephalopods are able learners, the basics of cephalopod behavior – feeding, escape, and mating – appear to be largely innate. For example, octopuses learn things in order to adapt to the specific micro-environments they end up in. The characteristics of these environments are impossible for aquariums to predict, and so they cannot be simulated. Feeding a cephalopod common local prey species so that it learns how to eat those species efficiently might help it succeed if it is released, but besides this one example there seems to be relatively little to do in the way of “preparing” a cephalopod for release.
Before I hash out some of the costs of providing enrichment to captive cephalopods, let’s consider what providing such enrichment entail. Anderson and Wood suggest several ideas for giant pacific octopuses, most of which could work with other species of cephalopods. The one that sticks out to me is feeding the animals a variety of live prey. This would provide them with a good deal of activity, a variety of problems to solve (how to catch and eat different species of prey,) and is very entertaining for the public to watch. Some cephalopods (cuttlefish come to mind – I’ve read cuttlefish keepers complaints about this) will only reliably eat live food, anyways.
The authors also suggest that the octopuses be given objects to explore, which can be smeared with fish drippings or have food hidden in them to attract the octopus and encourage exploration. In my favorite quote of the paper, they recount a particular use of this technique:
Wood and Wood… hid food in a play ship – the octopus had to “sink” the ship to get the proffered food. Such a demonstration with a large octopus… would interest the paying customers of a public aquarium by invoking a “sea monster” image.”
The future of cephalopod husbandry.
They also suggest the use of “training” to provide enrichment to octopuses (I put “training” in scare quotes, because some of their specific suggestions, such as smearing fish-smelling fluid on parts of the tank, don’t necessarily involve learning.) This seems like a moot point to me. There are two ways in which you can train a cephalopod – by rewarding it with food, or by punishing it with electric shocks (or some other unpleasant stimulus.) In the first case, you might as well simply give the animal the food, the capture of which seems like it would provide most of the activity inherent in training. In the latter case, well, who’s going to argue that training an animal by electric shock improves its quality of life or reduces its suffering (assuming that the training isn’t absolutely necessary, such as teaching it not to attack people or run into traffic, etc.)?
What would be the costs of providing this sort of enrichment to cephalopods? In my estimation, they would be small. Here’s my reasoning:
It should be relatively easy for aquariums, especially those near coasts, to obtain live prey to feed to cephalopods. By advertising the feeding times (as is done with the animals like sharks, dolphins, and sea lions) aquariums could turn this into a way to entertain visitors and draw more business. The increased popularity of octopus exhibits would likely make up for the extra cost of providing more live food. One of the complaints I hear about the giant pacific octopus exhibit at the Niagara Falls Aquarium is that it just sits there all the time. In the interest of furthering public interest in cephalopods, I make sure to write “Please publicize octopus feeding times!” in their guestbook each time I visit. I’m sure that if they did this, their visitors would be more interested in the octopus and happier with the aquarium overall.
Similar reasoning applies to constructing interesting enclosures that encourage cephalopods to explore. The public likes to see animals doing things, and the increased public interest will more than make up for the expenses of outfitting an octopus tank (which can be as cheap as a few plastic toys) These forms of enrichment are probably very cost effective, at least for public aquariums, even if they have only a small chance of benefit the captive animals.
When we consider animals used for research, the costs become larger. Giving animals a less monotonous environment may exaggerate inter-individual variation. It is usually argued that enrichment produces consistently healthy experimental animals, and so reduces variation in experimental results. The research that is used to make this argument in the case of mammals, however, has not been replicated in cephalopods. Without such evidence, it’s hard to say what effect different kinds of enrichment would have on behavioral experiments with octopuses. Such evidence would be rather expensive and time-consuming to obtain, and providing enriched environments to experimental cephalopods on the assumption that it would improve results could be, if that assumption were wrong, very costly as well. If behavioral research on cephalopods becomes more popular, this will become a more urgent question, and somebody will have to take on the task and expense of answering it.
Generally, providing enrichment for captive cephalopods seems worth it. Given the (even relatively slight) chance that they could benefit from basic environmental enrichment and the small cost of such enrichment, there’s no reason not to do it. The deal only becomes sweeter when you take into account the benefits to aquarium popularity and public education. Even if the cephalopods don’t benefit from it, it can hardly hurt.
Thanks for reading!
Anderson, R., & Wood, J. (2001). Enrichment for Giant Pacific Octopuses: Happy as a Clam? Journal of Applied Animal Welfare Science, 4 (2), 157-168 DOI: 10.1207/S15327604JAWS0402_10
After a moray eel attack (the octopus footage starts about 5 minutes into the video):
I wonder how that octopus coped afterwards. It seems to be swimming just fine, but it’s likely that, even if it could still function, it would get an infection or fall prey to another predator it was no longer strong enough to get away from. Thanks to Glenn Patton for that great video!
Next on this week’s cephalopod video revue, Let’s take a look at some cuttlefish. I never get tired of watching these guys change color.
Both of the users who posted these videos (ScandanavianDiveTeam and Tmukouhara) have a bunch of other dive videos, so click through and check them out.
Finally, the Shedd Aquarium in Chicago just posted a neat video starring one member of the cephalopod family that never gets enough attention: the nautilus.
An article came out this week in the US News and World Report covering research being done on Humboldt Squid populations off of the Pacific coast of the US (including some quotes by newly-named MacArthur fellow and oceanographer Kelly Benoit-Bird.) They mostly avoided the “vicious man-eater” stereotyping of the squid that I so deplore, but managed to squeeze in a toned-down version of it that I found quite funny:
Mexican fishermen call them diablos rojos, or “red devils,’’ because they are extremely aggressive. “I don’t think I would choose to get in the water with them when they are actively feeding,’’ Benoit-Bird said, noting, however, that they lose their propulsion when captured. Even so, “you don’t want to stick your fingers in their mouths,’’ she added.
Pretty much any animal is dangerous when you stick your fingers in its mouth. I have 2 pet rabbits – cute little fluffy bunnies – and I wouldn’t recommend sticking your fingers in their mouths, especially while they are eating. Somehow, this testimony doesn’t quite convince me.
Finally, I’m still looking for submissions for Encephalon , the psychology/neuroscience blog carnival. Drop me a line on twitter ( @Cephalover ) or via email ( mike.lisieski (at) gmail (dot) com ) to submit a post!
As I promised in the title, here are some baby octopodes (Octopus rubescens, the east Pacific red octopus, to be exact.) These guys are so small that you can see the individual chromatophores on them (the reddish spots)!
For comparison, here’s a photograph of an adult O. rubescens, graciously provided to the world by Taollan82:
Those little buggers have quite a bit of growing to do!
Moving on: “Sharktopus”, the long-awaited film about a Navy-engineered half-shark half-octopus monster, airs tonight on Syfy. Not having a TV, I won’t be watching, but it looks pretty incredible. Check out the trailer:
Two things I noticed: first, whoever performed that theme song deserves lots of credit – it makes the preview. Secondly, Sharktopus seems to have an appetite for skinny women in bikinis. You’d think that, being a presumably efficient predator, it would be attracted to prey with more body fat (eg. prey that would yield a higher calorie intake to expenditure ratio,) and it seems like there’s no danger that a large person could hurt it – but it still almost exclusively goes after skinny beach babes. How could the producers fail to consider the probable features of Sharktopus’s energetics? They must not be biology geeks.
I have three exams next week, so I won’t have another substantive post up until Thursday-ish, at least. In the mean time, enjoy this (under-viewed – only 600 views in 2 years!) video of some captive-bred baby cuttlefish munching on some copepods: