The vertebrate jaw is a product of evolution — we have a serially repeated array of pharyngeal structures as embryos (and fish retain them in all their bony glory as gill arches), and the anterior most arch is modified during our development to form the jaws. The fact that they're serially repeated raises an interesting possibility: what if, instead of just the one developing into a jaw, others were transformed as well? You could have a whole series of jaws!
One animal has done exactly that. The moray eel has modified one of the more posterior pharyngeal arches into a second pair of jaws, with a set of muscles that can slide it forward to bite prey already held in the mouth.
a, Posterior placement of the pharyngeal jaws in relation to the skull. The arrow points to the pharyngeal jaws. b, Pharyngeal jaws in their protracted position. The arrow points to the upper pharyngobranchial. Scale bar for a and b, 1 cm.
I know, everyone is thinking HR Giger and the Alien movies … and it is similar to that. These animals have toothed jaws in their throat, and a set of protrusive and retracting muscles to move them forward and back.
Why? In teleost fish, the jaws are wonderfully complex and malleable, and are impressive examples of morphological diversity. In most predatory fish, the common technique for capturing prey is suction feeding: opening the jaws, depressing the floor of the oral cavity, and flaring the opercula (gill flaps) creates a partial vacuum that sucks the prey into the mouth and holds it there while the teeth engage in their bloody work. This is a problem for eels, since they're adapted for living in confined spaces and narrow crevices — a morphological feature that requires expanding the mouth and pharynx may not work well. And if they can't use suction to draw food deeper into the throat, it might drift away each time they open their mouth to take another bite.
The moray has evolved a new eating strategy. Bite into the prey with the usual jaws, and then reach forward with the pharyngeal jaws and bite again. Open the main jaws and release, and the pharyngeal jaws pull the prey deeper into the mouth. The main jaws bite and hold again, and the pharyngeal jaws can reposition and bite more. The food is ratcheted deeper and deeper into the gullet by pairs of jaws taking turns to seize and tug.
The pharyngeal jaws can be seen in this quicktime movie. The eel bites on a bit of squid, and then about half way through the clip, you'll see a disturbing, creepy something between its gaping jaws reach forward and bite into the meal. It is so cool, and so unexpected.
It's a wonderfully, beautifully wicked mechanism.
(click for larger image)
The left dentary has been removed in a–c, and the left maxilla has been removed in b and c. a, Pharyngeal jaw apparatus at rest. b, Pharyngeal jaw protracted: the levator internus (LI) and levator externus (LE) protract the upper jaw into the oral cavity, whereas the rectus communis (RC) protracts the lower jaw. During protraction, the upper pharyngobranchial is dorsally rotated by contraction of the LI and the obliqus dorsalis (OD). c, After prey contact, the adductor (AD) contracts to bring the upper and lower jaws together to deliver a second bite. The dorsal retractor (DR) and pharyngocleitheralis (PHC) retract the pharyngeal jaws back to their resting position behind the skull. Scale bar, 1 cm.
The closest resemblance to this mechanism elsewhere in vertebrates is snakes, which use gnathic transport in a similar way. They don't have quite as elaborate a set of pharyngeal jaws, but they do use a pharyngeal ratchet to pull prey down into their throat.
Mehta RS, Wainwright PC (2007) Raptorial jaws in the throat help moray eels swallow large prey. Nature 449:79-82.
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So, do you know of any creatures that have acid for blood?
"So, do you know of any creatures that have acid for blood?"
Ann Coulter?
I think I'd take my chances snogging the moray eel.
Tis the work of the devil.
Ooh, a pharyngeal ratchet - I'll bet you're going to use that move in the big framing smackdown.Nisbet: prepare to met your moray.
Wow. That's really freaking cool. I had no idea.
Heard about this on NPR this morning. Just saw the movie. Wicked awesome!
Are 'pharyngeal jaws' what you used to scare off Pivar?
That was my first thought too... the writers of the movie were obviously ahead of the curve ;-)
So they're not *social* morays, then...
No, but they're awful tasty, especially when served up Japanese style.
O tempura! O morays!
OK, Now tell us how cyprinid fishes, which have no teeth in their jaws, and are generally pipette feeders, do it. You de man!
sometimes i'm really happy there's a "deep bottom of the sea" so that the things there don't move into my neighborhood.
Oh, wow.
Can I get a set of those installed?
Posts like this are the reason I come back to Pharyngula.
That is absolutely terrifying.
"When you wade in a creek.....
..and an eel bites your cheek.....
...it's a moray....."
This is like, the coolest thing I've heard for weeks.
Holy crap. That is amazing.
Fascinating. Gripping, even (sorry, couldn't help it).
Added bonus: this helps me visualize the utter visceral ferocity of the final scene between Mason Verger and his sister in _Hannibal_ (the book, which was far better than the movie by several orders of magnitude, in my opinion).
I love it when science and literature come together!
In Ichthyology class during my undergrad, we got to pick up and examine a moray skull. Badass - very scary looking, what with the big sharp pointy teeth everywhere. But the pharyngeal jaws were not included, so I had no idea just how freakin' cool these things are.
#'s 12 & 15,
Whatever is the matter with you?!
Please come join me for a dive on my local reef and I'm sure I can change your minds.
When da lagoon hits your eye like an octopus pie, there's a moray!
Squid in a ring ting-a-ling-a-ling, ting-a-ling-a-ling
And the reef is tropo bella"
Little fish'll play tippi-tippi-tay, tippi-tippi-tay
Like a gay octopella.
Oh, n'the starfish are cool in'da clear tidal pool,
there's aaaay moooray!
Nooooo! No! No! No! No! Snakes use palate bones with teeth on them (the pterygoids in this case) for that purpose. The left and the right pterygoid move alternately. The whole affair is termed the pterygoid walk. The pterygoids stay in the skull throughout, completely unlike the pharyngeal jaws of the moray, and they are ordinary dermal bones that we have, too, not homologous to gill arches. There is nothing pharyngeal about them.
You can see teeth on the palate of the moray in the drawings above. Having teeth on the palate is the normal condition for bony vertebrates; mammals and birds + crocodiles are the freaks for having lost all of them.
It's just like in Alien!!!! :O
Pharyngeal Jaws are common in fish, and are partly used to define many groups of upper boney fish in general.
They are far from unique. Here, look around:
http://www.google.com/
#16: In fact, after the NPR story, the host and reporter sang three verses of that song. Kept mostly on pitch, too!
What they didn't explain was the reasons why this might be a bigger advantage for eels than for other fish, and hence why it's reasonable that it only evolved in them. (Man it's hard to write about evolution without using terms that make it sound goal-directed!)
Whoa.
It looks like we'll have to dust off and nuke the morays from orbit. It's the only way to be sure.
Wow. That's really freaking cool. I had no idea.
What he said.
Yes, the cichlids are famous for them (having differently shaped teeth in the normal and the pharyngeal jaws gives them a lot of possibilities for easy adaptation to weird ecological niches, without having to evolve a mammal-style differentiated dentition in one jaw). Pharyngeal jaws that are so freakishly and stunningly mobile are apparently unique, however.
Yes Dave, but they are not only common to Cichlids, but are in fact a rather defining trait in Perciforms in general, which makes Pharyngeals jaws down-right everydayish-for-fish, and are not the weird odd unique trait PZ seems to state they are..
I have seen morays on a few dives and always thought they looked like something I should be wary of. Now I'm *really* glad I've stayed well away. It's always best to just see the wildlife, not interact with it.
That's just plain cool!
I'm having flashbacks of Lou Gossett Jr. getting his comeuppance in The Deep...
Proof that the moray is as cool as he is ugly.
Ann Coulter's blood is cesium hydroxide. Far right on the pH scale.
For some reason the moray in that movie reminds me of a muppet. I think it's the eyes.
When an eel
bites your thigh
while you're swimming by
that's, a moray
Thanks for explaining this marvelous creature more fully.
I, too, heard the NPR item while at work this morning. I was listening to headphones and marveled while the researcher explained now the Moray deals with its prey. Then the reporters launched into "That's a Moray." Hilarious and totally unexpected. It made my day.
I just watched that quicktime movie about ten times in a row. Fascinating.
Holy $%#& *&#$%#!! Wow who knew! #@#$!!
I'm surprised neither PZ nor the NPR report went into the other common feeding technique used by morays:
when faced with a prey item that is simply too large to swallow whole, they will tie themselves in a knot, run the knot up their bodies until it reaches their head, and rip off a big hunk of whatever they have their teeth sunk into as they pull their head through the knot.
I used to demonstrate this nightly to visitors at the Catalina Marine Science Center (Big Fisherman Cove, near the isthmus).
I would take a large, frozen, king mackeral or small bonita, drill a hole through the skull, and tie a rope through it.
then I would take the onlookers down to the rocks at the base of the pier, and dangle the frozen fish in the water between the rocks.
sure enough, within a couple of minutes, one of the large (up to 5 feet or so) morays would inevitably bite onto the frozen fish. Whereupon, I would actually pull the moray all the way out of the water, still attached, and it would tie itself in a knot and end up removing an actual large hunk of frozen fish before dropping back into the water.
now, don't let it be said that they are vicious beasties that attack divers, because they are normally quite shy and very rarely attack divers, even when provoked. However, it was always instructive to divers who would not afterwards be so incautious as to stick their hands in unexplored holes in the rocks.
BTW, anybody who ever wants the demonstration for themselves, if you have a boat and plan to head for Catalina in the future, I'd be happy to oblige.
When an eel dashes out
and it bites off your snout
that's a moray
(any more verses out there?)
You should check out the American Angler (Lophius Americanus), the ne plus ultra of suction feeding ambush predators. The gullet has teeth that roll the prey into the gut. Efficient!
It was a green moray that, many years ago, taught me never to reach into a hole in a reef.
I got away unscathed, but was glad there are no candiru in the USVI.
It really makes me wonder how it took so long for anyone to realize this. I mean, moray eels aren't exactly rare. You'd think someone would have cut open a dead one and spotted the extra set of jaws before 2007. It's amazing how many discoveries are still out there yet to be made, hiding in plain sight.
Please come join me for a dive on my local reef and I'm sure I can change your minds.
where's your local reef, Fernando?
erk, no thanks. i know what my limitations are, and swimming desperately from maddened eels is an area where i fall short. my dad nearly had a finger removed by a moray diving when he was a youngun. no block-chipping for me.
Ichthyic, over the years I've spent a lot of time in the water and have seen more than my fair share of morays on the reef but I've yet to see one tie itself into a knot. I was planning on diving this Saturday but the seas here are going to be a bit rough so I won't be able to test this on the weekend but you can be sure that I will be on the lookout for an opportunity to do so in the very near future. Don't worry I will be very very careful. I don't type too well with my toes.
Oh sorry my local reef is near Fort Lauderdale Florida. I live in Hollywood and Kayak Scuba with www.kayuba.org
heh, I have a buddy in Sarasota.
It's not hard to get a moray to do this:
-get a fish that's far too large for them to swallow
-go to a reef area where you know one or more hang out
-use the fish to lure one out of it's hole
-let it get a good grip on the fish, but don't let it retreat into it's hole.
almost every time, if it doesn't let go (rare), it will indeed tie itself in a knot.
heck, I've been watching morays do this since I was 15, though I must admit, I'm not sure if I recall having experimented with tropical morays to see if they do the same thing as the temperate ones. No reason to doubt that they do, however.
... be happy to show you anytime you want to do a dive in the Southern California area.
oh, btw, do you photograph any of your underwater forays?
website?
"It really makes me wonder how it took so long for anyone to realize this. I mean, moray eels aren't exactly rare. You'd think someone would have cut open a dead one and spotted the extra set of jaws before 2007. It's amazing how many discoveries are still out there yet to be made, hiding in plain sight."
Because, as I stated above, this "IS" common knowledge to people who study fish, as pharyngeal jaws are extremely common. This paper is just working out the unique details of this particular fishes version of these jaws...
That was just amazing! SO COOL!
It really makes me wonder how it took so long for anyone to realize this. I mean, moray eels aren't exactly rare. You'd think someone would have cut open a dead one and spotted the extra set of jaws before 2007.
I think they knew about the extra jaws, they just had no idea how mobile they were.
Morays do some other neat stuff, including cooperative fishing with grouper. Grouper comes along, "asks" a moray for help, the eel comes along and they share a meal.
I figured there had to be some vids out there of tropical morays doing the "knot", and of course, there are:
http://www.youtube.com/watch?v=oSE3gbAKslU
in a tank, but it's a tropical snowflake moray.
I had forgotten I used to have a tank with one who did this as well when I was about 12.
When...a...pharyngeal jaw
Pulls you into its Maw
That's a Moray...
When a fish bites your face
and it looks like a snake
it's a moray...
"whheeeeen you swim in da sea,
and an eel bites your knee,
dat's a moray..."
Of course we all know that Ann Coulter no longer has any blood. But before she turned into a zombie vampire... it was nasty stuff.
When an eel bites your thigh
and the pain makes you cry
that's a moray
I think that verse is from a Spider Robinson book.
Robster, thanks. Interspecies cooperative hunting is almost unknown.
BTW, the pair do not share a meal. One or the other succeeds and immediately swallows the prey whole. The benefit is the much higher success rate for each.
Um. This is kinda disturbing. I looked at the video Ichthyic provided, and at the end, the other videos that it provides are almost all about Ann Coulter. Seriously, here's a list of the ones I got:
"Zebra Moray Mating Dance"
"Ann Coulter, Canada, and Vietnam"
"Carlson and Coulter take on Canada"
"Ann Coulter Crazy on the Today Show"
"Adam Corolla hangs up on Ann Coulter"
"Late Show - Clinton's reply to Coulter"
"Ann Coulter gets owned"
"O'Neal in Beijing"
Does YouTube look at the last page you visited and pick out words or something?
Ya know, this is just the sort of thing I read PZ's blog for.
I am never so entertained as when I am in WAY over my head.
[i]The food is ratcheted deeper and deeper into the gullet by pairs of jaws taking turns to seize and tug.[/i]
So very much like the vagina dentata.
Does YouTube look at the last page you visited and pick out words or something?
interesting question. It might track cookie data on your comp.
try disabling cookies in your browser, delete your internet cache and recent history files, and then go back there and see if the same pattern emerges, or whether you get something entirely different.
make sure you have cookies turned OFF.
... and if you thought it was checking the last page you visited...
what were you doing perusing Ann Coulter's stuff???
HUH?
:P
the only value in her materials is in using as an emetic, IMO.
hmm, tried it myself.
nope. seems the coulter links are pre-programmed for some reason. my guess would be a tag system someone is abusing.
that'd be amazing... if the eel in the movie wasn't so obviously a sock puppet.
Snorkeling late in the afternoon in Martinique, we saw a beautiful chain-patterned moray come out of its hole to hunt, poking its head into holes all over the reef. I wonder if the original adaptation wasn't for living in a hole, but for pulling other creatures out of theirs. Then the transition to hole-living and lurking for prey would be easy.
Ichthyic - am I the only one who was screaming "Use tweezers, for god's sake!" when watching that video? Sure, it was a little eel, but the fingers seemed a tempting target.
Am I...the only one who thinks 'Jaws of The Moray' would make for a great band name?
Am I the only one who found himself humming "All things bright and beautiful" why reading this?
> (any more verses out there?)
When you swim in the sea
And an eel bites your knee
That's a moray...
when you fall off the dock and an eel bites . . . oh, never mind.
That's what I think. The pharyngeal jaws themselves are not presented as a new discovery.
(BTW, I didn't write only cichlids had them. I wrote they were famous for theirs.)
RANDOM USELESS TRIVIA! Giger's creature didn't have eyes. His initial "brainstorm" sketches of it did, but he decided making it eyeless made it look more eerie. Also, the second jaw started out as a proboscis: http://upload.wikimedia.org/wikipedia/en/thumb/b/b0/Hrgigeralien.jpg/20…
"When it bites on your butt
And your eyelids swell shut
That's a moray."
My favorite for its sheer goofiness.
#70: Yes, I think you were the only one humming "All Things Bright and Beautiful", everyone else was obviously humming "That's a Moray".
What's that thing in the reef
With the spare set of teeth?
That's a moraaaay...
my guess would be a tag system someone is abusing.
The morays have a good slander case, then.
Adrian #69, I reckon 'Jaws of the Moray' would have made a great name for a Hammer horror film.
Read the Nature paper online but couldn't get the movies on the ancient work PC, so thanks to PZ for the copy.
After so long working on snakes the almost total Otherness of the moray's system is a lovely shock. I find the evidence supports the hypothesis of a marine origin of snakes (note framing; the guys on the other side of this question, of course, are just Denialists), which means tetrapodal varanoid-like snake-ancestors lost their forelimbs and gained elongate bodies doing the same sorts of stuff as morays are doing now, either cornering aquatic prey in crevices or ambushing out of them. Before the invention of the 'pterygoid walk', the snake's ratchet was primitively achieved by 'snout-shifting': after the initial bite, fix the posterior maxillary and mandibular teeth on one side while turning the head towards that side, shifting the contralateral teeth forward; then alternate. Propalinally mobile pterygoids came along later, and probably twice independently, in ancestors of macrostomatans and typhlopoids.
Interestingly, the moray's pharyngeal (pharyngular?) apparatus is like a schematic version of a snake's maxillary and mandibular arches, only upside-down (opening widely at the front of the top, not the bottom set of elements). The shape and attachment of the teeth is also very snake-like (rare in tetrapods, but not unprecedented for fish... which is why some galaxiid fish pharyngeal fragments from New Zealand were mistakenly identified as snake pterygoids a few years back). Yet it all seems a bit lightweight; I feel some doubt whether a system like this would be of much use in a putatively air-breathing terrestrial moray-analog... but maybe it'd just need more beefing up. Or maybe not even that: in snakes in any case the ratchet is not required to drag the weight of the prey anywhere: it just helps the snake move its head around the outside of the prey item. (Is that framing again? - you leave the intended victim of your rhetoric exactly where he is, but move the issue to envelop him...?)
Adrian #69, I reckon 'Jaws of the Moray' would have made a great name for a Hammer horror film.
Read the Nature paper online but couldn't get the movies on the ancient work PC, so thanks to PZ for the copy.
After so long working on snakes the almost total Otherness of the moray's system is a lovely shock. I find the evidence supports the hypothesis of a marine origin of snakes (note framing; the guys on the other side of this question, of course, are just Denialists), which means tetrapodal varanoid-like snake-ancestors lost their forelimbs and gained elongate bodies doing the same sorts of stuff as morays are doing now, either cornering aquatic prey in crevices or ambushing out of them. Before the invention of the 'pterygoid walk', the snake's ratchet was primitively achieved by 'snout-shifting': after the initial bite, fix the posterior maxillary and mandibular teeth on one side while turning the head towards that side, shifting the contralateral teeth forward; then alternate. Propalinally mobile pterygoids came along later, and probably twice independently, in ancestors of macrostomatans and typhlopoids.
Interestingly, the moray's pharyngeal (pharyngular?) apparatus is like a schematic version of a snake's maxillary and mandibular arches, only upside-down (opening widely at the front of the top, not the bottom set of elements). The shape and attachment of the teeth is also very snake-like (rare in tetrapods, but not unprecedented for fish... which is why some galaxiid fish pharyngeal fragments from New Zealand were mistakenly identified as snake pterygoids a few years back). Yet it all seems a bit lightweight; I feel some doubt whether a system like this would be of much use in a putatively air-breathing terrestrial moray-analog... but maybe it's just need more beefing up. Or maybe not even that: in snakes in any case the ratchet is not required to drag the weight of the prey anywhere: it just helps the snake move its head around the outside of the prey item. (Is that framing again? - you leave the intended victim of your rhetoric exactly where he is, but move the issue to envelop him...?)
Ooops, sorry for the double-... er, triple-post.
I'd hate to rain on your parade, but we're not going to last seventeen hours against those things!
Wow, thanks for posting this. It's amazing! I love learning new things about science, nature, and atheism every day from you.
Love Giger's work. The best art imitates life.
David Marjanović is (as always) correct above. (Hi David--have "known" you for years via lurking the Dinosaur listserve archives).
Lago: Anyone with a vertebrate bio course in their background knows about pharyngeal jaws; it's the protraction that's new and (oh so) cool...I agree though that PZ's wording implies otherwise.
Ichthyic: thanks! I knew hagfish were self-knotters but did not know about morays. (My one trip to Catalina was a highlight of my life (many reasons)).
John Scanlon: Could you briefly summarize what you think are the best bits of evidence for a "marine" origin of snakes? As opposed, I mean, to a) aquatic (freshwater) or b) fossorial?
thanks
p.s. Alien, yes, but it also reminded me of of the giant worm-things in Tremors, w/ Kevin Bacon. Does any one know of an earlier fictional portrayal of jaws-within-jaws?
Fascinating and creepy. Not as creepy as the sphincter eye, but still creepy.
Indeed it would be a good Hammer flick, but only if Christopher Lee does the voice-work.
Also the name's Adnan, not Adrian. I'm apparently named after the fellow who started the clan to which Mohammad belonged to, and my last name translated to "Believer" in Farsi.
In a parallel universe, there's a devout muslim named Darwin Nietzsche Al-Dawkin.
JohnnieCanuck, FCD @ 60, You are correct. I forgot that the lucky one just swallows the meal whole. That's what I get for relying on memory alone.
Awesome. Now we need prey's point of view of this incredible beauty! Someone *try* to feed it a miniature camera. Pretty Please!
Coolest
Thing
Ever
Sure, it was a little eel, but the fingers seemed a tempting target.
yup. learned that one the hard way myself, doing exactly what you see in the video.
which brings up another amazing thing about morays-
they're tremendously hardy buggers, and can even stand being flung across a living room by a surprised 12 year old.
suffice it to say I did indeed use tweezers after that.
The morays have a good slander case, then.
well, better than Pivar did, anyway.
:p
I suspect the monster designers for Tremors got the idea for the teeth arrangement from lampreys and hagfish.
Now that the serious stuff is out of the way...
What do you call an expedition for eels? A moray foray.
What does an eel call it when it's infected by a rhinovirus? A moray code.
Thought of another one...
Can you name the eel who played Buddy Sorrel on The Dick van Dyke Show?
Moray Amsterdam.
Sven said:
"Lago: Anyone with a vertebrate bio course in their background knows about pharyngeal jaws; it's the protraction that's new and (oh so) cool...I agree though that PZ's wording implies otherwise."
Are you agreeing with me, or attempting to correct me? If you are agreeing with me, well..thanks, if you are disagreeing with me, please show what you are disagreeing with...
In the absence of the expert, let me try... It looks like the snakes' closest relatives are a bunch of Cretaceous marine "lizards", including the great and mighty mosasaurs. Furthermore, the burrowing snakes are not the deepest branch on the snake family tree, which is instead where we find large marine Cretaceous animals that retained small hindlegs.
Today's sea snakes are something else, however -- a branch within the elapids, the group that the cobra and the venomous snakes of Australia belong to.
There is a common hypothesis that Ann Coulter's prominent Adam's apple is best explained by her being a transgendered person. And while this would be amusing given her hatred of the less common sexualities, I have always believed that there must be a better hypothesis.
And now we have one: Ann Coulter's peculiar throat bulge is actually her pharyngeal jaw. While it would take a very brave person to verify this in person, I believe the photographic evidence is fairly strong, as you can see below.
The Beauty of Conservatism
--b9
When it ties in a knot
And it steals what you've got
That's a moray
Like a slimy shoelace
With an 'orrible face
That's a moray
"and it bites off you ****s
with pharyngeal jaws
dat's a moray"
er, YOUR ****s
On a related note, the Mosasaurs had pterygoid teeth.
A few nice pics here: http://www.oceansofkansas.com/SDSMT.html
That's normal.
Thanks, David. If the evidence for a marine origin of snakes is only the habitat of their known sister group(s), I don't find that very persuasive.
Hi Sven (& thanks David for filling in),
it's not just the first sister group; that of course would be unconvincing. It goes something like this:
terrestrial varanoids (mosasauroids (dolichosaurs (more dolichosaurs (Pachyrhachis (Haasiophis (terrestrial snakes)))))), where the brackets denote monophyletic groups and all the mosasauroids, most of the dolichosaurs, and at least two successive branches at the base of snakes are marine. There's only one reasonable way to optimise the 'habitat' character when you get these relationships as the result of phylogenetic analysis.
There are alternative phylogenetic hypotheses but they seem, to this palaeontologist, to require heroic amounts of selective under-carpet evidence-sweeping.
Whennnn the eel at you place
takes a bite outta your face
That's a moray
"That's a Moray" is also a song by a Cayman singer called "Barefoot Man". (www.barefootman.com)
Waaay back in the day when I learned to scuba I had a cassette tape. "Dirty Old Man" and "Don't Squeeze the Tomatoes" were particular favorites, too.
I can only remember a few of the lyrics:
"See that thing on the reef
with a billion sharp teeth
that's a moray
put your hand in that crack
and you won't get it back
from a moray
he can swim he can dive
but no he'd rather hide
in the coooorall..."
Thanks John!
interesting.
...and one reason it's interesting is that it reminds me of Dawkins's essay The Giant Tortoise's Tale, in which he points out that terrestrial tortoises have aquatic ancestors, which had terrestrial ancestors, which had (as did we all back then) aquatic ancestors.
If the snakes really have a marine origin then terrestrial snakes too have aquatic-->terrestrial-->aquatic ancestors, and modern seasnakes go one better: aquatic (the seasnakes)-->terrestrial (their elapid ancestors)-->aquatic (the putative marine protosnakes)-->terrestrial (lizard ancestors)-->aquatic (proto-tetrapods).
Very cool!
I vaguely recall that one of the more colourful Roman Emperors (Caligula?) kept Moray eels in a tank and fed them on slaves. It's probably in Suetonius.
Some more verses from an online friend of mine:
When you wade in the sea and a fish bites your knee, thats a moray
When you swim near the sand and an eel bites your hand, that's a moray.
When an eel reaches out and bites off your snout, that's a moray.
When you mix up some tuna and rice, add some cheese, that's a mornay.
When you're hit down the pub by some big Kiwi thug, that's a Maori.
If y'think _King Kong_ was all that, go see _Vampire Bat_; that's some more Wray.
Nooooo! No! No! No! No! Snakes use palate bones with teeth on them (the pterygoids in this case) for that purpose. The left and the right pterygoid move alternately. The whole affair is termed the pterygoid walk. The pterygoids stay in the skull throughout, completely unlike the pharyngeal jaws of the moray, and they are ordinary dermal bones that we have, too, not homologous to gill arches. There is nothing pharyngeal about them.
You can see teeth on the palate of the moray in the drawings above. Having teeth on the palate is the normal condition for bony vertebrates; mammals and birds + crocodiles are the freaks for having lost all of them.
Yes, the cichlids are famous for them (having differently shaped teeth in the normal and the pharyngeal jaws gives them a lot of possibilities for easy adaptation to weird ecological niches, without having to evolve a mammal-style differentiated dentition in one jaw). Pharyngeal jaws that are so freakishly and stunningly mobile are apparently unique, however.
That's what I think. The pharyngeal jaws themselves are not presented as a new discovery.
(BTW, I didn't write only cichlids had them. I wrote they were famous for theirs.)
In the absence of the expert, let me try... It looks like the snakes' closest relatives are a bunch of Cretaceous marine "lizards", including the great and mighty mosasaurs. Furthermore, the burrowing snakes are not the deepest branch on the snake family tree, which is instead where we find large marine Cretaceous animals that retained small hindlegs.
Today's sea snakes are something else, however -- a branch within the elapids, the group that the cobra and the venomous snakes of Australia belong to.
That's normal.
How the hell did that evolve? Some things seem easier to lose. but dear god.. that's wax on wax