Anyways, head on over, check it out, comment around, and I’ll see you next month! Again, let me know if you would like to host a future edition (email me at mike (dot) lisieski (at) gmail (dot) com, or PM me on twitter @Cephalover.)
In the mean time, though, I wanted to bring you some more information about the family of squid that this guy belongs to (the Chiroteuthid family.) It turns out that I’m having some trouble digging up information on these species, as they’re relatively understudied – in my searches, though, I came across something totally unrelated (and totally awesome) that I just have to share with the internet. So, I’ll have to leave you wanting that primer on Chiroteuthid biology (I’ll probably get to it after finals) for this blurb on a very unusual octopod.
In 2004, Mark Norman, Renata Boucher, and Eric Hochberg published a description of a previously unknown species of octopod from several male specimens that was gathered in the western Pacific Ocean. They placed it in its own genus, calling it Galeoctopus lateralis. In most respects, this guy appears to be pretty typical for a deep-water octopod – in one respect, though, he’s strikingly different. See if you can tell what’s unique about this guy from this drawing of his body plan:
From Norman, Boucher, and Hochberg (2004)
Note the conspicuously short arm – more precisely, the third arm on the right side. This is the arm that contains the ligula, the organ that male octopuses use to inseminate females. Let’s take a closer look at this:
From Norman, Boucher, and Hochberg (2004)
It’s a bit hard to see in this photo, but on the oral side of the third tentacle (that is, the side that usually faces inwards, towards the mouth) there is a small opening. Inside this opening are tiny “teeth-like lugs”, which the authors suggest that males use to remove the sperm bulbs that previous males have left inside of the female they are mating with, thereby increasing the competitiveness of their own sperm. This is a pretty standard evolutionary strategy – if you prevent the other guy’s sperm from doing their thing, your own sperm (and thus your genes) have a better chance of successfully being incorporated into the next generation of your species.
The authors hypothesize that this unique structure is complementary to an equally unique bit of anatomy that is found in females of the species, an enlarged muscular appendage of the oviduct:
Male Galeoctopus may use the mouth-like transverse groove of the muscular ligula to grip and rupture the sperm bulbs of previous suitors… The muscular flange on the distal oviducts of the female may be related to a vigorous mating process, these muscles potentially anchoring the oviducts during copulation to prevent them tearing free from the visceral wall.
NORMAN, M. (2004). THE SHARKCLUB OCTOPUS, GALEOCTOPUS LATERALIS, A NEW GENUS AND SPECIES OF DEEP-WATER OCTOPUS FROM THE WESTERN PACIFIC OCEAN (CEPHALOPODA: OCTOPODIDAE) Journal Molluscan Studies, 70 (3), 247-256 DOI: 10.1093/mollus/70.3.247
First order of business: I got to feed a giant Pacific octopus (GPO) a scallop today! By hand! It was pretty incredible. Thanks to the good folks at the Aquarium of Niagara (particularly Dan, the Director of Exhibits,) I got to see the nuts and bolts of the octopus enclosure and interact with Twister, their resident octopus (who is a female, if anybody was wondering.) It was a great time. One of the most interesting was seeing how they keep her from escaping – the top of the tank is open, but has 2-foot high walls around it that are covered in astroturf-like plastic material. Although Twister doesn’t seem to mind the feel of the stuff, her suckers can’t grip it and so she can’t pull herself out. Neat, right?
I’d also like to plug their Pepsi Refresh project, while I’m at it. They want to win a $50,000 grant to build a new coral reef exhibit, with the goal of increasing public awareness of the importance and precariousness of reef health in light of climate changes. This aquarium does a lot to educate the public in the region (I’ve hardly gone there without seeing a school field trip,) and so it would be money well spent. To help the Aquarium of Niagara win this grant, please head over to their page and vote for them! You can sign in with your facebook account or create an account with them – it only takes a second. You can vote once per day, and can even do it with your cell phone by texting their code, 102344 to Pepsi (73774). Please do all you can to help make this exhibit a reality!
Moving on: a friend just brought a new video game to my attention: Octodad. From the official website:
Octodad is a third person adventure game about destruction, deception, and fatherhood. The player controls Octodad, a dapper octopus masquerading as a human, as he goes about a day of his life. His existence is a constant struggle, as he must master mundane tasks with his unwieldy boneless tentacles while simultaneously keeping his cephalopodian nature a secret from his human family.
They have a free download on their website. I’m currently downloading it – I’ll post an update another day when I’ve had a chance to play it. The concept, though, is golden.
One of the projects that The Southern Fried Science Network and friends supported during the Donor’s Choose initiative, “A Look Inside: Squid Dissection” aimed to get squid dissection kits for a class from Wicklund Elementary School in California to use in their biology lessons. I’m happy to say that this project is fully funded, and Mr. L’s class will get their squids (and get to dissect them, too!) Here’s the thank-you letter he sent:
Thank you all for supporting my class and helping to support my project. It is so hard in this day to teach Science in fun and creative ways. My students are eagerly waiting to do this project. They have been very excited about this since I mentioned it to them. I can’t wait to tell them that this project is now a go!
Your donation will help my students gain the practical knowledge needed to conduct a real science experiment.
On behalf of my students, thank you very much!
You should be proud of yourselves, dear generous donors (readers or not.) It’s a good day when a kid learns about a squid.
To recap the last post on the Euprymna/Vibrio symbiosis: Euprymna scopoles (also known as the Bobtail squid) is a tiny species of squid that has two light organs in the underside of its mantle. Vibrio fischeri is a species of bacteria, of which some varieties can live inside of the bobtail squid’s light organs. These bacteria produce light, which the squid uses for camoflauge.
The story of how the two evolved together to make the working symbiosis is long, complex, and as of now incomplete – scientists are still piecing together all of the many adaptations that allow these two species to live together. I’ll try to bring both of us, dear reader, at least one step closer to making sense of it in this post.
A juvenile bobtail squid. Photo by Loh Kok Sheng (click through to see his blog.)
The important thing about this symbiosis is that it is selective. The squid has these little pouches which are just perfect for bacterial growth, but only one species of bacteria is found there. This involves a number of processes of selection – for example, the squid’s immune system sends cells into the crypts of the light organs to eat up invading bacteria, and the lining of the light organs secrete antimicrobial chemicals (like nitric oxide.) Vibrio fischeri has evolved to allow it to prosper under these conditions. The first step of the symbiosis, though, involves the bacteria and the squid finding each other. The ocean is big, and there are lots of bacteria and squid in it; how do these two get together so reliably?
Nyholm and McFall-Ngai address this in a 2003 paper that examines what they call “the first site of symbiont specificity”: the mucus that coats the opening of the light organ crypts in juvenile squid. Let’s start from the beginning:
A baby bobtail squid hatches from its egg. (Awwwww! So cute!) While it developed, its bacterial partner was nowhere to be found. After it hatches, though, a colony of V. fisheri will become established in its light organs within mere hours. Nyholm and McFall-Ngai looked at the surface of the mantle where the crypts open to the seawater and found that specialized cells in this area secrete mucus in response to the seawater that it would normally encounter right after hatching. This mucus helps trap bacteria, which can then colonize the light organ. V. fisheri normally make up about 0.1% of the bacteria found in seawater, though, so in order to beat out the competition, they must have some ability to interact with the light organ in a special way. Nyholm and McFall-Ngai hypothesized that the mucus layer on the outside of the light organ was key to this specificity, and conducted a number of experiments to test this idea.
First of all, they found that if they exposed hatchling bobtail squids to seawater without V. fisheri in it, all sorts of bacteria could be found in the light organ mucus. However, when they used seawater with small amounts of V. fisheri in it (again, on the order of one-tenth of one percent of the total bacteria in the water,) the colonies that formed in the mucus were almost exclusively V. fisheri. This indicates that this mucus excretion has some role in establishing the specificity of this symbiotic relationship, in that it somehow “screened out” all of the other species of bacteria that might have taken hold in the mucus and started to multiply.
Image of a V. fisheri colony in a bobtail squid light organ, labeled with green fluorescent protein. Aa, anterior appendage; pa, posterior appendage. (from Nyholm and McFall-Ngai, 2003)
They also determined that most of the V. fisheri present when they took their measurements had been collected from the water; this is in contrast to a scenario where a few cells were captured and then multiplied. To do this, they used a chemical called nalidixic that prevents cell replication while not affecting cell growth – when exposed to this chemical, bacteria won’t divide, they will simply elongate. By looking at how long V. fisheri cells grew in the light organ mucus, the experimenters determined that the cells were growing at a low rate in the mucus – in fact, they were growing much more slowly than they do in a plain culture! Thus, it’s unlikely that a few cells were captured by the mucus and then dividing into the large colonies they found; rather, there may exist some way for V. fisheri to selectively adhere to the mucus and be efficiently collected from the water (the authors say that this is unlikely, but not completely ruled out – it seems to me a likely explanation, especially taking into account the results of a series of studies that I’ll write on soon.)
The authors than tried using killed V. fisheri, to see if there is something specific to the presence of the bacteria (for example, some component of their outer membrane) that inhibits the growth of other bacteria. They found that, although killed V. fisheri could still adhere to the light organ mucus, they did not prevent the growth of other species of non-symbiotic bacteria. This implies that the bacteria perform some active process that prevents the growth of other bacteria in the light organ and allows V. fisheri to establish its dominance there, even though the mere presence of V. fisheri bacteria doesn’t kill other kinds of bacteria.
This symbiosis, then, which occurs very quickly and very specifically, depends (as most great things do) on mucus. Somehow, V. fisheri interacts with the squid’s secretions to beat out it many competitors. Interestingly, though (and I won’t cover the methods here, for time’s sake) the authors also found that the V. fisheri that colonize the crypts initially are not necessarily able to produce luminescence. It seems that the species of bacteria is selected during the initial stages of colonization, but that later on, specific strains that are better able to produce light are selected for while those that do not produce light are expelled or die off – each stage of selection no doubt involving a complex set of signals between the squid and the bacteria.
Thanks for reading!
Nyholm, S., & McFall-Ngai, M. (2003). Dominance of Vibrio fischeri in Secreted Mucus outside the Light Organ of Euprymna scolopes: the First Site of Symbiont Specificity Applied and Environmental Microbiology, 69 (7), 3932-3937 DOI: 10.1128/AEM.69.7.3932-3937.2003
To get psyched up for a second post on the Eurpymna/Vibrio symbiosis, I decided to raid Flickr for the best images I could find of bobtail squid! As a quick note, I’ve decided to only use images licensed under Creative Commons licenses – it saves me the trouble of getting explicit permission to use each image from the owner, and I generally like to support open-access media of all types. Thanks in advance to all the photographers whose work I’ve embedded for generously letting the world use, remix, and share their photos!
On to the squids! This first series shows an adorable little specimen burying itself in substrate:
Next we’ve got a floater!
And… back to the sand:
This is, in a nutshell, what bobtail squids do – sit in the sand, float around, catch some food, repeat. What would an animal photography post be, though, without some hanky-panky?
Thanks for reading/looking! Be sure to click through and check out the photographers’ other works – there’s a lot of great underwater shots in their photostreams.
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