What’s the deal with the beak, anyway? Where does it come from, evolution-wise? Do other marine animals have beaks? Is it terribly stupid to wonder if there is some link between bird beaks and squid beaks? Just curious.
Brucesays
PZ, I’m not what you would call spiritual, but I have religiously avoided watching anything to do with “Jackass” until you just tricked me. Thanks a lot.
PZ, I’m not what you would call spiritual, but I have religiously avoided watching anything to do with “Jackass” until you just tricked me. Thanks a lot.
You’re doing yourself a disservice. Jackass the movie is actually hilarious. Infantile? Sure. Funny? Definitely.
Wait a second. That’s not really a single squid sperm right? I’m afraid I’m being pathetically credulous to even pose the question, but damn it, I’m not a biologist and I come here to LEARN.
My favorite Wildboyz episode was when Steve-O and Pontius dressed up in a Zebra suit and let lions attack them. Enjoy the video: http://youtube.com/watch?v=N2rWrF5EwzA
Forrest Princesays
Who says science can’t be fun, or even funny?
Although this may not be science in a strict sense of the term, it is at least an interest in the natural world, and the giant squid is a fascinating animal. I remember seeing a documentary where the sonar dome of a big navy(?) ship had been attacked by a giant squid. The rubberized coating on the dome had been torn up pretty good by the squid.
Maybe the squid was just looking for some luvin’.
Geralsays
“”That’s amazing. I feel like I actually learned something today!””
haha.
Ph(i)Nk 0says
About the beak, funny you should ask, there’s a fascinating article about it on Not Exactly Rocket Science just now: A squid’s beak is a marvel of biological engineering. If only the author had given it another title, because you know how words are used these days… if it is engineering then who is the engineer?
What’s the deal with the beak, anyway? Where does it come from, evolution-wise?
Don’t a few other molluscs also have “jaws”?
Do other marine animals have beaks?
“Marine animal” is not an evolutionarily meaningful term.
Is it terribly stupid to wonder if there is some link between bird beaks and squid beaks?
Yes :-) Sorry, couldn’t help. Beaks have evolved lots of times independently within vertebrates, and vertebrate jaws have nothing to do with cephalopod jaws.
David Marjanović, OMsays
What’s the deal with the beak, anyway? Where does it come from, evolution-wise?
Don’t a few other molluscs also have “jaws”?
Do other marine animals have beaks?
“Marine animal” is not an evolutionarily meaningful term.
Is it terribly stupid to wonder if there is some link between bird beaks and squid beaks?
Yes :-) Sorry, couldn’t help. Beaks have evolved lots of times independently within vertebrates, and vertebrate jaws have nothing to do with cephalopod jaws.
HPsays
Squid beaks: Ed’s article that Ph(i)Nk 0 linked is terrific. Of course, our gracious host here at Pharyngula is far too modest to link to his detailed article, “Cephalopod Gnashers,” at the old site.
ID has a penis, too, Stein. If you’d like to see ridicule done well and effectively, this is some of the best:
This is just recreation, scathing ridicule of Stein and Expelled that works, and is fun to view. It isn’t very informative, just an accurate description of the dregs of American apologetics:
Comic actor and game show host Ben Stein isn’t at all happy, according to the trailers for his spurious-looking new documentary, Expelled: No Intelligence Allowed, in which he berates in overheated, lachrymose and rhetorically manipulative ways the American academic establishment’s reluctance to recognise intelligent design, the pseudoscientific, inbred second-cousin of biblical creationism, for which Expelled offers straightforward propaganda. Stein isn’t making a political crossover here, just a formal one – from TV comedy, where his talents really lie, to political apologias, where his talents simply die. His deeply rightwing political opinions haven’t shifted one iota since he was a speechwriter for Richard Nixon. (If you can believe it, Stein was once suspected of being Deep Throat.)
Given that kind of apprenticeship, amid the lying, wiretapping and campaign-trail double-dealing, you’d expect a dishonest documentary, and apparently, we’ve got one. From the parts I’ve seen – the first 10 minutes online – it seems to deploy all the loaded-dice arguments, the overdog’s deep-seated sense of victimhood and conventional rightwing hysteria. Stein lambasts academe for dismissing the work of “ID scientists”, even when they are bankrolled by the rancid likes of the Discovery Institute, a think-tank inseminated yearly with funds from California savings and loan heir Howard Ahmanson Jr, who in 1985 told the Orange County Register: “My goal is the total integration of biblical law into our lives.” Man, I can’t wait for that, Ben, the priests running everything and we live like it’s Ireland in the 1940s. Par-tay!
And yes – you get all that in the first 10 minutes.
[The rest of the article isn’t about “Expelled” or Stein, but it can be found here:]
I wish we could just treat it the way that John Patterson does. The fact is that we have to and do consider it carefully and show how and why ID and its various whines are wrong, but then they just moan pitiably again about how persecuted they are. Which wouldn’t matter, except that politicians and too much of the public listen to them whinge.
Thanks for linking that, Ph(i)Nk 0. This month’s (or last month’s) Scientific American also had a blurb about the density gradient of squid beaks.
And as for squid porn (Kseniya’s helpful links aside), I happen to be President of the local chapter of NASTÉ (the North American association of Squid/Tentacle habituÉs). Some consider us to be a fishy bunch, but once you get to know us, we have a way of suckering you in.
cattasays
Funny, I actually read about their beaks earlier today; Spiegel Online has an article about (recent, I assume) discoveries about the structure of the beak tissue and how squids manage not to hurt themselves with their own beaks (the process of using the beak is described as “like cutting meat with a blade that has no handle”). The article’s in German, sorry… If I understand correctly, the key is that the hardness of the beak is gradated; it has more chitin at the base than at the tip, and more protein at the tip than at the base, and the major factor determining the hardness of the tissue is the water content. Interesting stuff.
And I hate, hate, hate people who act like these guys. I’d have been very tempted to give the beak a good squeeze while they had their fingers in it…
cattasays
Aw, crap. That’s what I get for not clicking on all the links in the comments — the study the article I linked to is based on is the same as in Ph(i)Nk 0‘s link. Sorry you guys. (but at least now you have a pop-science summary in German at your disposal ;) )
Robster, FCDsays
OM NOM NOM NOM OUCH!
LARAsays
DaveX, I believe that bird beaks are composed of keratin, and squid beaks are composed of chitin, same stuff as the radula in snails. Remember that squid are mollusca right? So you can see how the chitinous mouthparts of snails changed over time to become a beak in squid. As far as bird beaks are compared with squid beaks, the squid beak would be considered convergent evolution rather than a homologous structure.
Kseniyasays
I happen to be President of the local chapter of NASTÉ (the North American association of Squid/Tentacle habituÉs). Some consider us to be a fishy bunch, but once you get to know us, we have a way of suckering you in.
Wait wait don’t tell me: Your motto is “We Give Good Cephalo!”
spencersays
We’re sorry, this video is no longer available.
Mikesays
PZ (and all other squid aficionados), I was amazed yesterday to read this Yahoo story:
I would have thought this sort of knowledge would have been discovered at least a century ago. I guess it just goes to show how little we know about our head-footed friends. Here’s where I incur the wrath of Dr. Myers by giving much love and respect to the blue-ringed octopus, the coolest cephalopod there is!
Mikesays
Sorry to give a link to an article with content that had already been mentioned a couple of times. Sorry also for giving a link that is extremely long and annoying and travels almost completely off of the computer screen (at least on mine it does).
Wait wait don’t tell me: Your motto is “We Give Good Cephalo!”
Well, it was, until we discovered most of our members were ‘pod fetishists, while a smaller arm of our chapter are content to, well, we just call them ‘Inkies’.
Our main issue now is advocacy for the recognition of human-cephalopod civil unions. To this end, I’m organising a campaign that will culminate in a march on our respective parliaments and capitols, this upcoming ‘Octo’ber. If any Pharyngulites are interested in supporting this worthwhile fight for freedom and justice, I urge you to contact me at the “Calamari? Can-a-Marry!” Campaign office, C/O this blog.
Kseniyasays
Mike, it’s best to embed long URLs into [a] tags with shorter descriptions. That prevents the hard left-justification of the entire thread.
On the scale of life’s hardships, though, I’d put it at about a 0.001. ;-)
Is it terribly stupid to wonder if there is some link between bird beaks and squid beaks?
Yes :-) Sorry, couldn’t help. Beaks have evolved lots of times independently within vertebrates, and vertebrate jaws have nothing to do with cephalopod jaws.
I disagree; it’s not a stupid question from a naive observer, David. And there may be a link; after all, bird wings and bat wings are homologous as forelimbs, even though they’re not homologous as wings.
I take your point about their not being homologous as beaks, but I’d want to see the analyses before concluding they have nothing to do with each other at any level of abstraction at all, not just the obvious leaf node you’re referring to.
Mikesays
Could the beak be a sort of remnant of the molluscan shell, as the pen is?
Sven DiMilosays
Well, it’s not like the squid and bird beaks have nothing to do with each other–they both surround mouths that are probably homologous…probably.
Turtles are MUCH closer to birds than are squid, but their keratinous beaks are probably not homologous either.
Kseniyasays
“Inkies” … LOL!
Re: Can-A-Marry! Brownian, I believe you might have a chance at enlisting what’s left of The Beatles in the aid of your noble cause!
toddahhhhhsays
Seeing them drop and wrestle the squids, I had an epiphany. I’ve devised the GSWWF (Giant squid world wrestling federation)! (Soon to be GSWWE due to concerns from environmental groups). Once the squidmania fades and they are too washed up to wrestle anymore, they could have a reality show on VH1, “Squid Knows Best” is the working title, for now. Although taping will be halted due to a juvenile squid accident pending felony charges for crashing a car and seriously injuring his friend.
Mikesays
#35:
Don’t forget that there’s a good chance the main giant squid’s slippery spouse will divorce him and take half his fish and a large portion of his ink sack. Brother.
DanioPhDsays
Sven @ #33:
Well, it’s not like the squid and bird beaks have nothing to do with each other–they both surround mouths that are probably homologous…probably.
Actually, molluscs are protostomes (i.e. the first invagination, or ‘hole’ made by the gastrulating embryo is the mouth) whereas vertebrates and many other more closely related critters are deuterostomes–the first hole we make as embryos becomes the anus. Those parameters for homology are a little too relaxed for my taste ;-)
Gregsays
Someone clear up my confusion. PZ’s earlier post said that squids have a “special tentacle” which is not a penis. When they are asked to hold the “penis,” the guy says that it’s not a penis – just a tentacle. So… which is it? Penis or special tentacle?
I have never said penis so many times in one paragraph before.
Kseniyasays
It’s good to see David, thalarctos and Sven teaching the controversy.
Wow! Many interesting links there. That one about the makeup of the beak was especially interesting– and if anyone missed the first-hand account of diving with Humboldts, they should go back and dig it.
Thanks for the helpful answers, everyone!
(And David M– you might employ some etiquette in the future. I’ve seen the ocean precisely ONCE in my life, and I certainly don’t know anything about the jaws of molluscs. If “marine animal” doesn’t work for you, try suggesting a more appropriate term.)
windysays
Well, it’s not like the squid and bird beaks have nothing to do with each other
Calcification processes in molluscs and vertebrates might also have some sort of connection… (squid beaks aren’t nacre though, and bird beaks are only partly bone, but still…)
Silisays
DanioPhD,
Does that mean, then, that vertebrates are anal-retentive, while molluscs are oral-retentive? Or is it the other way round?
DaveX, you’ll find that David M. isn’t one to throw barbs or snap his beak at any honest inquiry. He’s one of the most even-tempered and generously disposed persons in the ‘hood. Consider it an uncharacteristic slip. :-)
molluscs are protostomes (i.e. the first invagination, or ‘hole’ made by the gastrulating embryo is the mouth) whereas vertebrates and many other more closely related critters are deuterostomes–the first hole we make as embryos becomes the anus. Those parameters for homology are a little too relaxed for my taste ;-)
I take your point, but it’s exactly this kind of examination you’re presenting that will ultimately answer the question. I’m not conversant enough with the genetic processes that form the holes in invertebrates to know whether we’re talking about different genes that do similar things (analogy, not homology), or whether we’re talking about the same genes that get just get triggered in different orders in different species, which could involve some degree of homology of the resulting structures related to those gene products. (I study sun bears, which are comfortably mammal-vanilla, embryologically speaking, to compare with humans; molluscs are terra incognita to me.)
I’d want to know that before categorically ruling it out, and I certainly wouldn’t characterize a question from someone who hasn’t delved into it in the degree specialists have done as “stupid”. “Stupid” would be persisting in it after the evidence is in (and you know who you are–I’m looking at you, Dembski, Behe, Dr. Steve, et al!).
Until the evidence is in, or someone has explained to Dave how it would or would work, he’s just generating a possible hypothesis at his level of available information; a process which may be naive, but is certainly not stupid.
If you got to go, may as well show off your huge tool and get one last “happy ending” in the process…
DanioPhDsays
Thalarctos @#46
I’d want to know that before categorically ruling it out, and I certainly wouldn’t characterize a question from someone who hasn’t delved into it in the degree specialists have done as “stupid”. “Stupid” would be persisting in it after the evidence is in (and you know who you are–I’m looking at you, Dembski, Behe, Dr. Steve, et al!).Until the evidence is in, or someone has explained to Dave how it would or would work, he’s just generating a possible hypothesis at his level of available information; a process which may be naive, but is certainly not stupid.
Agreed–I wholehearteldy encourage questions and classify very few of them as ‘stupid’ (which is saying something–I’ve had more jaded, unmotivated undergraduates in the past few years than I care to count). Certainly Dave’s query was a good one, IMO, and I wouldn’t dream of casting aspersions at anyone who posed such a question from an honest desire to learn something new. I just want to clarify that I never thought–or wrote–any such thing.
My response about the blastopore was mostly just to be silly. ‘Homology’ can be based on very vague criteria, and if you take it to its broadest extreme, almost any two things could be deemed homologous in some way. Asses and holes in the ground come to mind :)
Your point about molecular homology is a good one–after all, it took molecular genetics to appreciate that the ventral nervous system of bilateral insects, etc. was patterned by the same genes as the dorsal nervous system of vertebrates and their allies. Turns out old Geoffrey St. Hilaire wasn’t such a raving lunatic after all! I wouldn’t be at all surprised to learn that protostome mouths and deuterostome mouths were in fact patterned by some of the same genes. I’m at home now without institutional access to journals, and someone will probably beat me to it, but I’ll look it up as soon as I’m reconnected to the academic world. However, even if this bears out, I’m still not sure it’s appropriate to term these respective mouths ‘homologues’. Dig?
Certainly Dave’s query was a good one, IMO, and I wouldn’t dream of casting aspersions at anyone who posed such a question from an honest desire to learn something new. I just want to clarify that I never thought–or wrote–any such thing.
No, I know you didn’t.
I wouldn’t be at all surprised to learn that protostome mouths and deuterostome mouths were in fact patterned by some of the same genes. I’m at home now without institutional access to journals, and someone will probably beat me to it, but I’ll look it up as soon as I’m reconnected to the academic world. However, even if this bears out, I’m still not sure it’s appropriate to term these respective mouths ‘homologues’. Dig?
Yup–I come to the party having been mentored by a great old (human) gross anatomist in the classic (pre-genome sequencing) tradition. Under his mentorship, I took his ideas about knowledge representation in human anatomy in a comparative anatomy direction. He taught me far more than I ever taught him, although I do remember explaining to him the difference between quadrupeds and tetrapods, and that, contrary to his mental image, not all fish had paired sets of fins.
But for all our differences in species focus, we were both dealing with gross anatomy, where much of the literature refers to structures as “homologous” or “not homologous” across species. For my thesis and dissertation, I had a GSR (graduate school representative, assigned by the grad school to make sure that the exam proceeds appropriately) who was also a genome scientist. He told me afterwards, smiling, that it was very jarring to him to hear the word “homology” used as it was in my defense–as a molecular biologist, he is used to “X%” homology, not as “on” or “off” as classical anatomists tend to speak of it.
All of which is a very long and rambling way of agreeing with you–it may well not be appropriate to call these different mouths “homologues” in the classic sense that sun bear prostates and human prostates are almost identical genetically-related structures. Yet, if they are indeed generated by the same structural genes, there would seem (by definition) to be some kinds of homologous relationships going on, which was my main objection to David’s “not at all” characterization. As gross anatomical structures, it would be silly to say they are X% homologous, and yet the all-or-nothing approach–as you rightly observe–doesn’t seem quite right in this case either.
MandyDaxsays
I spent part of every work day looking at colonoscopy photos, and it doesn’t bother me. I seriously threw up a little in my mouth while watching this. Next time, please RickRoll me instead. PLEASE!:6
LARAsays
Dammit, I er. Snails come after squid evolutionarily, when torsion occurs, not before as I wrote.
Sven DiMilosays
I wouldn’t be at all surprised to learn that protostome mouths and deuterostome mouths were in fact patterned by some of the same genes…. However, even if this bears out, I’m still not sure it’s appropriate to term these respective mouths ‘homologues’. Dig?
Well, me neither, which is why I emphasized the “probably” in the first place.
If mouth-forming genes are homologous (at some %!) and simply expressed at opposite ends of the tube, though, I’d consider protomouths and deuteromouths to be homologous structures. They’d have to have been inherited from a common ancestor that had a mouth.
What’s the deal with the beak, anyway? Where does it come from, evolution-wise? Do other marine animals have beaks? Is it terribly stupid to wonder if there is some link between bird beaks and squid beaks? Just curious.
PZ, I’m not what you would call spiritual, but I have religiously avoided watching anything to do with “Jackass” until you just tricked me. Thanks a lot.
You’re doing yourself a disservice. Jackass the movie is actually hilarious. Infantile? Sure. Funny? Definitely.
Wait a second. That’s not really a single squid sperm right? I’m afraid I’m being pathetically credulous to even pose the question, but damn it, I’m not a biologist and I come here to LEARN.
“The squid doesn’t have a penis.” – you, in this post:
http://scienceblogs.com/pharyngula/2008/03/nothing_but_ignominy_for_the_g.php
See, they told us not to trust Big Science!
That was absolutely disgusting, yet hilarious!
My favorite Wildboyz episode was when Steve-O and Pontius dressed up in a Zebra suit and let lions attack them. Enjoy the video: http://youtube.com/watch?v=N2rWrF5EwzA
Who says science can’t be fun, or even funny?
Although this may not be science in a strict sense of the term, it is at least an interest in the natural world, and the giant squid is a fascinating animal. I remember seeing a documentary where the sonar dome of a big navy(?) ship had been attacked by a giant squid. The rubberized coating on the dome had been torn up pretty good by the squid.
Maybe the squid was just looking for some luvin’.
“”That’s amazing. I feel like I actually learned something today!””
haha.
About the beak, funny you should ask, there’s a fascinating article about it on Not Exactly Rocket Science just now: A squid’s beak is a marvel of biological engineering. If only the author had given it another title, because you know how words are used these days… if it is engineering then who is the engineer?
(.)(.)
Well that vid had everything – drama, romance, suspense, comedy, and sex. And I learned something today as well.
Somehow, I don’t see squid porn catching on.
Don’t a few other molluscs also have “jaws”?
“Marine animal” is not an evolutionarily meaningful term.
Yes :-) Sorry, couldn’t help. Beaks have evolved lots of times independently within vertebrates, and vertebrate jaws have nothing to do with cephalopod jaws.
Don’t a few other molluscs also have “jaws”?
“Marine animal” is not an evolutionarily meaningful term.
Yes :-) Sorry, couldn’t help. Beaks have evolved lots of times independently within vertebrates, and vertebrate jaws have nothing to do with cephalopod jaws.
Squid beaks: Ed’s article that Ph(i)Nk 0 linked is terrific. Of course, our gracious host here at Pharyngula is far too modest to link to his detailed article, “Cephalopod Gnashers,” at the old site.
Oh?
ID has a penis, too, Stein. If you’d like to see ridicule done well and effectively, this is some of the best:
That was oddly
arousingentertainng.Is it optimistic of me to think that that might actually get some kids started on a career as a
hentai starbiologist?Wow! It’s a veritable cephalopod-fest today!
Thanks for linking that, Ph(i)Nk 0. This month’s (or last month’s) Scientific American also had a blurb about the density gradient of squid beaks.
And as for squid porn (Kseniya’s helpful links aside), I happen to be President of the local chapter of NASTÉ (the North American association of Squid/Tentacle habituÉs). Some consider us to be a fishy bunch, but once you get to know us, we have a way of suckering you in.
Funny, I actually read about their beaks earlier today; Spiegel Online has an article about (recent, I assume) discoveries about the structure of the beak tissue and how squids manage not to hurt themselves with their own beaks (the process of using the beak is described as “like cutting meat with a blade that has no handle”). The article’s in German, sorry… If I understand correctly, the key is that the hardness of the beak is gradated; it has more chitin at the base than at the tip, and more protein at the tip than at the base, and the major factor determining the hardness of the tissue is the water content. Interesting stuff.
And I hate, hate, hate people who act like these guys. I’d have been very tempted to give the beak a good squeeze while they had their fingers in it…
Aw, crap. That’s what I get for not clicking on all the links in the comments — the study the article I linked to is based on is the same as in Ph(i)Nk 0‘s link. Sorry you guys. (but at least now you have a pop-science summary in German at your disposal ;) )
OM NOM NOM NOM OUCH!
DaveX, I believe that bird beaks are composed of keratin, and squid beaks are composed of chitin, same stuff as the radula in snails. Remember that squid are mollusca right? So you can see how the chitinous mouthparts of snails changed over time to become a beak in squid. As far as bird beaks are compared with squid beaks, the squid beak would be considered convergent evolution rather than a homologous structure.
Wait wait don’t tell me: Your motto is “We Give Good Cephalo!”
We’re sorry, this video is no longer available.
PZ (and all other squid aficionados), I was amazed yesterday to read this Yahoo story:
http://news.yahoo.com/s/ap/20080328/ap_on_he_me/squid_beak;_ylt=AqqNcf24RN7f4tQzsS3HxXgPLBIF
I would have thought this sort of knowledge would have been discovered at least a century ago. I guess it just goes to show how little we know about our head-footed friends. Here’s where I incur the wrath of Dr. Myers by giving much love and respect to the blue-ringed octopus, the coolest cephalopod there is!
Sorry to give a link to an article with content that had already been mentioned a couple of times. Sorry also for giving a link that is extremely long and annoying and travels almost completely off of the computer screen (at least on mine it does).
…and a posse.
I can haz…?
Wait wait don’t tell me: Your motto is “We Give Good Cephalo!”
Well, it was, until we discovered most of our members were ‘pod fetishists, while a smaller arm of our chapter are content to, well, we just call them ‘Inkies’.
Our main issue now is advocacy for the recognition of human-cephalopod civil unions. To this end, I’m organising a campaign that will culminate in a march on our respective parliaments and capitols, this upcoming ‘Octo’ber. If any Pharyngulites are interested in supporting this worthwhile fight for freedom and justice, I urge you to contact me at the “Calamari? Can-a-Marry!” Campaign office, C/O this blog.
Mike, it’s best to embed long URLs into [a] tags with shorter descriptions. That prevents the hard left-justification of the entire thread.
On the scale of life’s hardships, though, I’d put it at about a 0.001. ;-)
I disagree; it’s not a stupid question from a naive observer, David. And there may be a link; after all, bird wings and bat wings are homologous as forelimbs, even though they’re not homologous as wings.
I take your point about their not being homologous as beaks, but I’d want to see the analyses before concluding they have nothing to do with each other at any level of abstraction at all, not just the obvious leaf node you’re referring to.
Could the beak be a sort of remnant of the molluscan shell, as the pen is?
Well, it’s not like the squid and bird beaks have nothing to do with each other–they both surround mouths that are probably homologous…probably.
Turtles are MUCH closer to birds than are squid, but their keratinous beaks are probably not homologous either.
“Inkies” … LOL!
Re: Can-A-Marry! Brownian, I believe you might have a chance at enlisting what’s left of The Beatles in the aid of your noble cause!
Seeing them drop and wrestle the squids, I had an epiphany. I’ve devised the GSWWF (Giant squid world wrestling federation)! (Soon to be GSWWE due to concerns from environmental groups). Once the squidmania fades and they are too washed up to wrestle anymore, they could have a reality show on VH1, “Squid Knows Best” is the working title, for now. Although taping will be halted due to a juvenile squid accident pending felony charges for crashing a car and seriously injuring his friend.
#35:
Don’t forget that there’s a good chance the main giant squid’s slippery spouse will divorce him and take half his fish and a large portion of his ink sack. Brother.
Sven @ #33:
Actually, molluscs are protostomes (i.e. the first invagination, or ‘hole’ made by the gastrulating embryo is the mouth) whereas vertebrates and many other more closely related critters are deuterostomes–the first hole we make as embryos becomes the anus. Those parameters for homology are a little too relaxed for my taste ;-)
Someone clear up my confusion. PZ’s earlier post said that squids have a “special tentacle” which is not a penis. When they are asked to hold the “penis,” the guy says that it’s not a penis – just a tentacle. So… which is it? Penis or special tentacle?
I have never said penis so many times in one paragraph before.
It’s good to see David, thalarctos and Sven teaching the controversy.
(I’m not exactly joking.)
Wow! Many interesting links there. That one about the makeup of the beak was especially interesting– and if anyone missed the first-hand account of diving with Humboldts, they should go back and dig it.
Thanks for the helpful answers, everyone!
(And David M– you might employ some etiquette in the future. I’ve seen the ocean precisely ONCE in my life, and I certainly don’t know anything about the jaws of molluscs. If “marine animal” doesn’t work for you, try suggesting a more appropriate term.)
Well, it’s not like the squid and bird beaks have nothing to do with each other
Calcification processes in molluscs and vertebrates might also have some sort of connection… (squid beaks aren’t nacre though, and bird beaks are only partly bone, but still…)
DanioPhD,
Does that mean, then, that vertebrates are anal-retentive, while molluscs are oral-retentive? Or is it the other way round?
Sorry. Freud came up in therapy recently.Off-topic comment: You’re either going to love this or hate it, PZ. But you’re no longer just a movie star. you’re a hip hop homeboy: http://www.youtube.com/watch?v=eaGgpGLxLQw&fmt=18
DaveX, you’ll find that David M. isn’t one to throw barbs or snap his beak at any honest inquiry. He’s one of the most even-tempered and generously disposed persons in the ‘hood. Consider it an uncharacteristic slip. :-)
On the Constitution of some Appendages of the Mollusca
I take your point, but it’s exactly this kind of examination you’re presenting that will ultimately answer the question. I’m not conversant enough with the genetic processes that form the holes in invertebrates to know whether we’re talking about different genes that do similar things (analogy, not homology), or whether we’re talking about the same genes that get just get triggered in different orders in different species, which could involve some degree of homology of the resulting structures related to those gene products. (I study sun bears, which are comfortably mammal-vanilla, embryologically speaking, to compare with humans; molluscs are terra incognita to me.)
I’d want to know that before categorically ruling it out, and I certainly wouldn’t characterize a question from someone who hasn’t delved into it in the degree specialists have done as “stupid”. “Stupid” would be persisting in it after the evidence is in (and you know who you are–I’m looking at you, Dembski, Behe, Dr. Steve, et al!).
Until the evidence is in, or someone has explained to Dave how it would or would work, he’s just generating a possible hypothesis at his level of available information; a process which may be naive, but is certainly not stupid.
D’oh! That should be, of course:
Invertebrates must have stolen my negation!
to bad those are not Giant Squid but are actually large Humboldt Squid,was surprised nobody caught that?
If you got to go, may as well show off your huge tool and get one last “happy ending” in the process…
Thalarctos @#46
Agreed–I wholehearteldy encourage questions and classify very few of them as ‘stupid’ (which is saying something–I’ve had more jaded, unmotivated undergraduates in the past few years than I care to count). Certainly Dave’s query was a good one, IMO, and I wouldn’t dream of casting aspersions at anyone who posed such a question from an honest desire to learn something new. I just want to clarify that I never thought–or wrote–any such thing.
My response about the blastopore was mostly just to be silly. ‘Homology’ can be based on very vague criteria, and if you take it to its broadest extreme, almost any two things could be deemed homologous in some way. Asses and holes in the ground come to mind :)
Your point about molecular homology is a good one–after all, it took molecular genetics to appreciate that the ventral nervous system of bilateral insects, etc. was patterned by the same genes as the dorsal nervous system of vertebrates and their allies. Turns out old Geoffrey St. Hilaire wasn’t such a raving lunatic after all! I wouldn’t be at all surprised to learn that protostome mouths and deuterostome mouths were in fact patterned by some of the same genes. I’m at home now without institutional access to journals, and someone will probably beat me to it, but I’ll look it up as soon as I’m reconnected to the academic world. However, even if this bears out, I’m still not sure it’s appropriate to term these respective mouths ‘homologues’. Dig?
No, I know you didn’t.
Yup–I come to the party having been mentored by a great old (human) gross anatomist in the classic (pre-genome sequencing) tradition. Under his mentorship, I took his ideas about knowledge representation in human anatomy in a comparative anatomy direction. He taught me far more than I ever taught him, although I do remember explaining to him the difference between quadrupeds and tetrapods, and that, contrary to his mental image, not all fish had paired sets of fins.
But for all our differences in species focus, we were both dealing with gross anatomy, where much of the literature refers to structures as “homologous” or “not homologous” across species. For my thesis and dissertation, I had a GSR (graduate school representative, assigned by the grad school to make sure that the exam proceeds appropriately) who was also a genome scientist. He told me afterwards, smiling, that it was very jarring to him to hear the word “homology” used as it was in my defense–as a molecular biologist, he is used to “X%” homology, not as “on” or “off” as classical anatomists tend to speak of it.
All of which is a very long and rambling way of agreeing with you–it may well not be appropriate to call these different mouths “homologues” in the classic sense that sun bear prostates and human prostates are almost identical genetically-related structures. Yet, if they are indeed generated by the same structural genes, there would seem (by definition) to be some kinds of homologous relationships going on, which was my main objection to David’s “not at all” characterization. As gross anatomical structures, it would be silly to say they are X% homologous, and yet the all-or-nothing approach–as you rightly observe–doesn’t seem quite right in this case either.
I spent part of every work day looking at colonoscopy photos, and it doesn’t bother me. I seriously threw up a little in my mouth while watching this. Next time, please RickRoll me instead. PLEASE!:6
Dammit, I er. Snails come after squid evolutionarily, when torsion occurs, not before as I wrote.
Well, me neither, which is why I emphasized the “probably” in the first place.
If mouth-forming genes are homologous (at some %!) and simply expressed at opposite ends of the tube, though, I’d consider protomouths and deuteromouths to be homologous structures. They’d have to have been inherited from a common ancestor that had a mouth.