Cephalove

Recently, the EU passed a directive that will require all of its member states to follow certain guidelines when using any animals for research. This piece of legislation, passed in 2010, replaced an older law from 1986 on the same topic. Besides updating the ethical and technical aspects of the law, it expanded the scope of the law to include more species than the 1986 law:

3. This Directive shall apply to the following animals:
(a) live non-human vertebrate animals, including:
(i) independently feeding larval forms; and
(ii) foetal forms of mammals as from the last third of their normal development;
(b) live cephalopods.

The first question that comes to mind is: why cephalopods? The answer, it turns out, lies in a document published by the Animal Health and Animal Welfare Panel of the European Food Safety Authority – their scientific report revealed that they had initially considered “all invertebrate animals” for inclusion under the law, but ended up recommending that cyclostomes (a group including lampreys and hagfish,) decapod crustaceans (like lobsters and crabs), and cephalopods should be included in the law. They also noted that other invertebrates, like spiders, tunicates, social insects and amphioxus are on the “borderline” of inclusion – that is, they seem to be complex enough (in their behavior and their nervous systems) that it is reasonable to think that they could experience pain or suffering, but there’s not enough evidence to suggest that they do to justify including them in the law. In any case, the only group of animals from this recommendation that ended up making it into the law was cephalopods, with crustaceans being excluded despite the Panel’s recommendation.

The reasons that the Panel cited for recommending cephalopods seem pretty straightforward; cephalopods exhibit what might be called complex cognitive abilities, being able to learn and remember rather flexibly, have large complex brains, and have strong behavioral responses to a variety of stimuli that we’d call noxious. These points, and their relationship to the possibilities of pain and suffering in cephalopods, are far from settled issues, and there’s a lot of arguments that can be made about why they may or may not be adequate justification for including cephalopods in the directive. In a sense, though, it is too late for these arguments; the directive has already passed, and will be in force as early as 2013.

As one might expect, this whole shebang was big news to cephalopod researchers. As I mentioned a few posts ago, a conference (dubbed Euroceph) was called so that cephalopod researchers could get together and talk about what the new law means to them and their work, and what needs to be done next. And there is a lot to be done.

The directive requires that certain criteria be met when using any vertebrate or cephalopod in research: for example, steps must be taken to minimize the animal’s pain and suffering, the animals used should be (if possible) bred for the purpose of research by regulated suppliers and not taken from the wild, and kept in enclosures that “are appropriate to their health and well-being.” One might run into some problems in applying these standards, which have been used in one form or another for regulating the use of vertebrate lab animals for many years, to cephalopods; for example, there is very little known about to biology of how cephalopods might feel pain, and what the consequences of that pain might be to a cephalopod’s health and behavior. There are only a few anesthetics that are used for cephalopods, and since we know almost nothing about the (presumably existent) pain system of cephalopods, we have no drugs to give them as pain-killers – indeed, it’s hard to even know where to start looking to identify drugs that would work as analgesics in cephalopods.

Another problem that came up repeatedly at Euroceph was the requirement for captive-bred animals. So far, there have only been a few limited successes at breeding cephalopods in captivity – among these, the only real successes have been with cuttlefish. Even in this case, though, captive-bred animals appear to behave differently than their wild-caught brethren (which isn’t really a surprise, if you think about how different the two lifestyles are;) perhaps more troubling, captive-bred cuttlefish seem to lose their ability to produce healthy offspring over several generations, limiting the extent of captive breeding programs. For researchers who want to study the behavior of cephalopods as it might be relevant to their lives in the wild, there is “a fundamental scientific problem” with requiring the use of captive bred cephalopods, said Rogen Hanlon, a cephalopod researcher at the Marine Biological Laboratory at Wood’s Hole. ) “If you want the best model [of cephalopod behavior], you use nature’s fittest, and that’s what you get from wild-caught animals.” Having to use captive-bred cephalopods for behavioral research could require research conducted using wild-caught animals that has been relied upon for decades to be re-done with captive-bred animals; even after this, it would still be difficult to predict what this research would mean in terms of how wild cephalopods actually behave.

While the EU directive contains very specific guidelines for the care of common lab animals like rats and rabbits, it contains almost no specific guidelines about caring for or handling cephalopods. This is because, while there is a long history of requiring that lab mammals be dealt with in a certain way (ie. they must have so much space, be given such-and-such a drug before each procedure to reduce pain, be fed every so often, be kept at such-and-such a temperature,) this is the first time that the research community has been required to come up with a standardized set of guidelines for using cephalopods. This might actually be an advantage to cephalopod researchers – they’re in the position now to shape these guidelines themselves, since there are virtually no other sources of information about how it is best to keep cephalopods in captivity. Hopefully, with the help of forthcoming regulations that are tailored to suit cephalopod research in particular, and more research into the health and husbandry of cephalopods, cephalopod research will continue without too much trouble.

Thanks for reading! Here, have a treat.

Some more reading, if you’re interested:

EU directive 2010/63/EU, on the protection of animals used for scientific purposes (the current law) (pdf)

EU directive 86/609/EEC, regarding the protection of animals used for experimental and other scientific purposes (the old law) (pdf)

The EFSA Scientific report: “Aspects of the biology and welfare of animals used for
experimental and other scientific purposes” (pdf)

If you like nature documentaries, you’ve probably seen the following clip (from the BBC’s “Planet Earth“):

Nautiluses are really cool – they’re misfits among cephalopods, having many tentacles and external shells while their fellow squids and octopodes are squishy and eight- or ten-armed. In this clip, at least, they come across as sort of mysterious, spending most of their time floating about in the abyss and only coming up to where it’s easy for us to see them at night. In fact, daily vertical migrations are common in the ocean, with a truly enormous number of organisms moving from shallow to deep waters and back again each day. The nautilus takes part in this migration, probably for its own safety – it’s harder for predators to see you (and eat you) if you stay where it’s dark.

Now I love learning new things about cool animals, but there’s something that I’m more interested in: how do we get that information? Presumably, biological facts are not true just because Sir David Attenborough says they are. How do the producers of that clip (or anybody, for that matter) know that this is what Nautiluses do?

It turns out that the answer is pretty simple: we monitor some of them for a period of time and see what they do. We can’t actually follow them underwater and visually watch them (because it would be difficult and expensive to do this for very long), so we have to use some sort of remote communications device (a radio or ultrasonic transmitter) to see what they do.

This is just what a group of researchers from the University of Queensland, have been doing for some years. Following up on reports about the possibility of daily vertical migrations in Nautilus, they attached ultrasonic transmitters to eleven nautiluses they caught around Osprey Reef in Australia. They kept track of each animal’s vertical movement, and described what they saw.

Nautilus fitted with ultrasonic transmitter - from Dunstan et al. 2011

As far back as 1899, a naturalist by the name of Arthur Wiley made note of the depths at which Nautilus live, both because it made them hard to study, and it meant that they were only be caught in shallow-water traps at night (although to be fair, he provides us no proof of this, only his word.) There are several other reports that support the idea that Nautiluses make vertical migrations (for example, a report published in Nature about the daily migrations of Nautiluses in Palau by Peter Ward et al. in 1984, and a report by Bruce Carlson et al. published in the journal Pacific Science about the same population of Natuiluses.)

Enter Dunstan and co-workers, the group of scientists at the University of Queensland that I mentioned earlier. They followed eleven individuals for up to around 80 days each and also used information from remote-operated vehicle dives to get a clearer picture of what Nautiluses spend their time doing. It’s easy to get an impression of their data from the following graph (click on it to see a bigger version):

Graph of individual recordings of Nautilus depths from Dunstan et al. 2011

Each line is one recording – there are multiple recordings from each animal. The “depth” of the line at the time of day shown at the top of the graph indicates the depth of the recording.

So what do we learn from this? Basically, we learn that it’s not as simple as “shallow at night, deep during the day” – just look at that graph! It doesn’t look like the movement of nautiluses is coordinated very well, either between animals or with times of the day. The authors note that the nautiluses often spend the daytime resting in relatively shallow water, and at night are found in all sorts of depths. In summary, it looks like there are several factors that influence where a nautilus ends up hanging out; purely physically, they can’t go deeper than about 800 meters (2600 feet) due to the high pressure (their shells implode at depths greater than this) or shallower than about 100 meters (320 feet) due to higher temperatures near the surface. During the day, nautilus appear to rest in shallow water or forage in deep water, while at night they are active and move through a whole variety of depths – this is probably influenced by things like food availability, the type and number of predators around, the conditions of the water, and the size and age of the animal. These results don’t contradict earlier results, although the authors note that different populations of Nautilus have been observed to have different patterns of behavior, and chalk this up to differences in their environments.

On a final note, I’d like to mention a study by Kanie and coworkers in which they determined what depth of water would cause a nautilus’s shell to break. To do this, they put a nautilus in a tank of water, and pressurized the tank until the nautilus imploded, all the while measuring its ventilation rate (how quickly it was “breathing”). From this, they came up with a maximum depth for nautilus of 785 meters. At first, this sounded like a cruel experiment to me, but on second thought, it was done very well. They used a single animal (although one might criticize them for that, it means that they only caused harm to a single animal) and in doing so adequately and rather elegantly answered a basic question in cephalopod biology that has implications not only for the ecology of living nautiluses but also for the study of nautiloid fossils and their distribution.

Thanks for reading!

NOTE: This post has been edited from its original form in response to Dr. Peter Ward’s comment (see below). As I did not have access to the research he mentions when I wrote this post (and still don’t), it was inappropriate of me to comment on the state of the field as I did. I’d like to sincerely apologize to Dr. Ward and his coworkers for any disrespect I may have shown to them and their work. I’ll do my best to bring myself up to speed on the research he mentions and include a more detailed discussion of it in a future post, so that I’m accurately representing the field. The text of this post before it was revised is available at this link.

BRUCE A. CARLSON, JAMES N. McKIBBEN, AND MICHAEL V. DEGRuy (1984). Telemetric Investigation of Vertical Migration of Nautilus belauensis
in Palau Pacific Science

Yasumitsu Kanie, Yoshio Fukuda, Hideaki Nakayama, Kunihiro Seki, Mutsuo Hattori (1980). Implosion of Living Nautilus under increased pressure Paleobiology, 6 (1)

Dunstan AJ, Ward PD, & Marshall NJ (2011). Vertical Distribution and Migration Patterns of Nautilus pompilius. PloS one, 6 (2) PMID: 21364981

Arthur Willey (1899). On a Zoological Expedition to the South Seas Proceedings of the general meetings for scientific business of the Zoological Society of London

Ward, P., Carlson, B., Weekly, M., & Brumbaugh, B. (1984). Remote telemetry of daily vertical and horizontal movement of Nautilus in Palau Nature, 309 (5965), 248-250 DOI: 10.1038/309248a0

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.

Another recent news story on the Humboldt (from The Globe and Mail): after “invading” northern waters, it has apparently left almost as quickly as it came.

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!

Thanks for reading!

Here at Cephalove, I tend to focus on octopuses.  The reason for this is pretty simple – out of all of the cephalopods, the most behavioral research has been done on octopuses, so they are the easiest cephalopod to write about.  To keep things lively, though, and to do something special to commemorate my first new post as part of the SFS Network, I want to dedicate this post to the oft-forgotten member of the cephalopod family: the nautilus.  Specifically, I want to talk about the eye of the nautilus. First, to cover the basics: nautiluses are the only extant cephalopods who still have an external shell.  There are only six species of nautilus still around, 4 in the genus Nautilus and 2 in the genus Allonautilus, with the most well-know being N. pompilus, the chambered nautilus (although this name accurately describes the shell of this species, all species of nautilus have chambered shells that help them achieve neutral bouyancy.)  A nautilus has about 80-100 small tentacles protruding from its shell, with which it catches food – mostly small crustaceans and fish.  They are found in the Pacific ocean, where they live in the deeper parts of coral reefs.  Here’s a picture (in the public domain – thanks, J. Baecker!) showing a chambered nautilus: You can’t see it too well here, but the eye protrudes on a stalk (the optic stalk, to be precise) from the head.  If you are used to looking at octopuses, cuttlefish, and squid (and aren’t we all, by now?) you’ll notice that the nautilus eye looks very different from theirs.  In fact, it is lensless, with the pupil being open to the water (sort of – there may actually be a sort of covering over it, but I’ll get to that later.)  This sort of eye is called a pinhole eye, and is also seen on giant clams.  It works very much like a pinhole camera, where an image is formed (albeit a relatively crude one) by restricted the angles at which light can enter the eye.  As those familiar with photography know, smaller pinholes create a sharper image; however, they are less sensitive, and require a much greater intensity of light to form a good image.  The nautilus’s eye works similarly, and so its pupil size is ultimately the result by a compromise between resolution and sensitivity.  A cross-sectional diagram of the eye (from Muntz and Raj, 1984) is shown below.  The dashed line shows the area where the eye connects to the rest of the body, and the thick line shows the location of the retina.  The gap at the right of the image is the pupil.

How good is the nautilus’s eyesight?  To find out, we’ll take a look at Muntz and Raj (1984), a paper that examines the spatial resolution of the nautilus eye through two different methods.  First, the authors used the nautilus’s natural tendency to maintain its orientation and direction in the water to determine its approximate visual acuity.  Then, they constructed model nautilus eyes and took pictures through them.  These are both elegant (although incomplete) ways to get an idea of what the nautilus sees, which is a very basic question in the problem of understanding the behavior of a particular organism.  I’ll skip over any more discussion of the anatomy of nautilus in this post – that’s another story for another day.  Muntz and Raj succinctly address the anatomy of the eye in the paper, so look there if you’d like more information on the subject.

To test the functional acuity of the nautilus’s vision, the authors exploited the animals optomoter response.  This is a reflexive motor behavior that keeps the animal in a stable orientation relative to landmarks in its environment.  This is very useful for a neutrally buoyant creature living in the water, who might otherwise easily be flipped over or turned around by water movement.  The authors did this by putting a nautilus into a tank in the middle of a drum.  The inside of the drum was striped, and the drum was slowly rotated around the tank.  If the nautilus could perceive the stripes, it would presumably rotate with the drum, trying to maintain its orientation to its surroundings.  If it could not perceive the stripes, it would let the drum rotate around it without attempting to correct for this movement.  A diagram of the apparatus, taken from the paper, is shown below.

By varying the width of the stripes, the authors were able to determine just how well resolved nautilus vision is.  After some calculation, the authors concluded that the nautilus has a minimum visual resolution between (roughly) 5 and 11 degrees of the visual field.  In comparison, a human has a minimum visual resolution resolution of about 1 minute of arc (1/60 of a degree.)  This means that as long as two objects are more than 1/60 of a degree apart in the image formed on a human’s retina, she will be able to tell that there are two objects there.  The nautilus, on the other hand, requires that the objects be at the very least 5 degrees apart in order to resolve them separately.  Thus, if stripes smaller than the equivalent of 5 degrees of visual field were used, the nautilus could not perceive them, and so showed no orienting response to this stimulus.

There’s a problem with this interpretation, though.  It might be that the 5-11 degree limit is not a limit of the eye, but rather just a differential behavioral response to different types of stimuli.  What if nautiluses tend to orient themselves to large objects (like the seafloor, or the light of the surface) but not to smaller objects (like animals swimming around them, or floating debris?)  This certainly seems adaptive. To help make the argument that the 5-11 degree limit was a limit of the eye itself, the authors constructed a model eye and took pictures through it.  In this way, they got a sense of the resolution of the image formed on the retina, which sets (albeit not directly) a lower limit on the resolution of the image that the brain can form.  Seen below is a set of such images.  The top left image shows the chart that they used.  The remaining three were taken through model eyes with increasing pupil diameters, corresponding to the range of pupil diameters found in wild nautiluses.  Under the experimental conditions, the top line is distinguishable at a minimum resolution of 4 degrees, and the bottom is distinguishable at a resolution of 2 degrees.  As you can see, some of the model nautilus eyes could not resolve either line, suggesting that the minimum resolution found in the behavioral test (5-11 degrees) agrees with the optics of the eye. Now that we know a bit about the optics of the Nautilus eye, what about that open pupil?  (I told you I’d get back to this.)  Having a gaping hole in one’s eye seems like it presents a problem to the animal, as it leaves the delicate interior of the eye open to the water – and any tiny particle or organism that might be floating around.  A simple experiment by W. R. A. Muntz (1987) discovered for one mechanism that protects the interior of the nautilus’s eye.  First of all, notice the groove that runs from the pupil to the bottom of the eyeball:

Photo by Hans Hillewaert

That groove is lined with cilia that sweep mucous downwards across the surface of the eye.  Muntz place drops of india ink on the surface of detached nautilus eyes, and found that the the india ink traveled downwards across the eye and into the groove.  Drops of ink were even seen moving over the opening of the pupil, indicating that this sheet of mucus is viscous enough to form a semi-solid covering over the pupil.  Without a lens to cover this opening, the nautilus seems to have evolved another way to keep particles out. Well, I hope you enjoyed this as much as I did.  Thanks for reading! W. R. A. Muntz (1987). A Possible Function of the Iris Groove of Nautilus Nautilus: the Biology and Paleobiology of a Living Fossil, 245-247 DOI: 10.1007/978-90-481-3299-7_16

W.R.A. Muntz, & U. Raj (1984). On the visual system of Nautilus Pompilus Journal of Experimental Biology, 109, 253-263

Next on my (long and growing) list of cephalopod photographers to feature here is Klaus M. Stiefel, a neurobiologist who currently works in Okinawa.  All of the photos in this post were taken by him.  He was cool enough to release them under a creative commons license, so feel free to use them, just don’t use them for anything commercial and make sure to give him credit (lots and lots of it.)  You can click through on all of the photos to access them on Flickr, including larger versions (which I always recommend – they make great desktop wallpapers.)  Let’s dive right in, shall we?

To start off, a portrait of an adorable cuttlefish of unknown species (if anybody can tell, please post it in the comments – I’m embarrassed to admit it, but I’m very bad at identifying species):

Moving right along, we have these two lovely photos of the flamboyant cuttlefish, Metasepia pfefferi.  Klaus calls this posture a “threat display”, although I’m pretty sure it is used both as a defensive behavior and during hunting, especially for shrimp and prawns.  My favorite thing about pictures of M. pfefferi is that they always look so relaxed, just because of the shape of their pupils.

Last in our illustrious lineup of cuttlefish is an unidentified individual who is expressing its papillae beautifully and showing off its ability to use binocular vision by looking at the camera with (count ‘em) two eyes.

You want squid?  We’ve got squid!  Well, a squid.  This is a juvenile squid (species unknown, though one of the commenters on Flickr suggests that it’s a bigfin reef squid, Sepioteuthis lessoniana) floating among the fronds of a sea lily.

Here is an octopus (again, species unknown) expressing a very striking white ring around its eye.  This looks to me like it might be related to the eye-bar body pattern component, which is used during defensive behavior by adult octopuses to obscure the shape of the eye or make it appear larger than it really is.

Here’s a great shot of some octopus arm suckers, showing various degrees of flexion of the suckers themselves.  I wish I knew the species of octopus that these belonged to.

I just love pictures of octopuses peeking out of things!  Here is the obligatory inquisitive-octopus-eyes shot:

In this series of photos, Klaus captured a dramatic color change in an octopus.  It looks to me like the octopus tried to camouflage itself, then decided that wasn’t going to work and began to hide under the rocks.

 Finally, we’ll close with a gorgeous photo of a cephalopod that is too often ignored: the Nautilus.

 Thanks for reading!