Danionella dracula

One of the evolutionary peculiarities of my favorite lab animal, the zebrafish, and of cypriniform fishes in general, is that they lack teeth. They lost them over 50 million years ago, and don't even form a dental lamina in development. So this photo of a cypriniform, Danionella dracula, gave me a bit of a start beyond just the nice fangs and the ghoulish name.

i-4944a09cf17cb5ef52f36340ce64ae79-danionella.jpeg

The story doesn't give much detail, but I'm going to have to look into this. Those are not true teeth, but spiny outgrowths of bone directly from the jaws.

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You're looking at the face of a new species of fish and judging by the two fearsome fangs, you'll probably understand how it got its scientific name - Danionella dracula. The teeth do look terrifying but fortunately, their owner is a tiny animal just 15 millimetres long. Ralf Britz from London's…
Ontogenetic allometry in the fang in the front-fanged Causus rhombeatus (Viperidae) displaces the fang along the upper jaw. Scale bars, 1 mm. We note the change in relative size of the upper jaw subregions: i, anterior; ii, fang; iii, posterior. d.a.o., days after oviposition. I keep saying this…
The incomplete skull of Nicrosaurus (formerly "Belodon"), one of the earliest-recognized phytosaurs. It is missing teeth and it did not have an extended downward extension of the palate (the outline that extends below the upper jaw marked by the dotted line) like modern crocodiles. From A guide…
Whales are beautifully ridiculous. They are majestic divers, in some cases plunging nearly two miles underwater. And yet sooner or later they must rise back to the surface to breathe air. They breathe through a rather ridiculous-looking hole on top of their head. Unlike fish, which often reproduce…

"And I'm going to rip those spiny outgrowths of bone out one by one"...or so goes the hatemail. Any word from the death threat posse lately?

Interesting. Evolution works in fascinating ways. It would be nice if someday you could be able to lay out the sequence and timing of the hox genes necessary for this to happen.

By Nerd of Redhead, OM (not verified) on 11 Mar 2009 #permalink

PZ,that one looks scary...

*drunk comment warning*

Ok,I found god,I really have.....he looks rather old and a little worse for wear,but he IS god,no doubt...
His name is ....Keith Richards.

Oh,WAIT,

there is another god,right here,his name is...Eric Clapton.
Now what??
Can I be a polytheist?
Please?

Cyprinids are food for real fish. Like cichlids. Not that I'm biased...ooh, I am!

That is so cool.

(Sorry, no puns, jokes, or geekery here. Just fishlove.)

As a non-biologist, what strikes me most about this fish is the apparently deformed eye. Is this a preserved specimen?

By 'Tis Himself (not verified) on 11 Mar 2009 #permalink

It's another Panda's Thumb phenomenon; the same useful functional structure is being formed by a different developmental route. Now you can ask the creationists why an intelligent designer wouldn't just give the thing teeth if it needed them :)

Thinking of weird marine biology moments, last night on Channel 4 Heston Blumenthal served his guests lampreys garnished with their own deep-fried notochords. Craig Revel-Horwood almost had a nervous breakdown. We also got to hear the line "I'm probably the first chef to put a testicle in Germaine Greer's mouth".

By Stephen Wells (not verified) on 11 Mar 2009 #permalink

What's up with the wrinkly eye?

I have crossed oceans of time to grow my bone fang...

By Ompompanoosuc (not verified) on 11 Mar 2009 #permalink

Posted by: Silva | March 11, 2009

That is so cool.

(Sorry, no puns, jokes, or geekery here. Just fishlove.)

And fishlove is not geeky?

By Janine, Insult… (not verified) on 11 Mar 2009 #permalink

It's probably a dehydrated specimen prepared for scanning EM. So, the eyes would not be deformed. They are merely dehydrated to some extent.
Stephanurus

By Stephanurus (not verified) on 11 Mar 2009 #permalink

Thanks, Stephanurus.

By 'Tis Himself (not verified) on 11 Mar 2009 #permalink

Yes, that is one dead fish: killed, fixed, freeze-dried, and coated with a thin layer of metal so that it can be observed in the vacuum chamber of a scanning electron microscope. The collapsed eye is entirely artifactual.

The BBC story on this is reasonable...

A large enough octopus wins against anything except a sperm whale.

By Stephen Wells (not verified) on 11 Mar 2009 #permalink

Can anyone explain how evolution can account for two perfectly formed, shaped, and placed bone protrusions? If this fish had no teeth and natural selection favored fish with protruding jaw bones (mimicking teeth), how does that produce these two particular protrusions? Why only canine-like teeth and why only two?

Maybe a primer in teeth evolution is in order. The evolutionary factors that produced teeth could be in play here.

Fish are awesome. Not only do they put teeth (the only anatomical element worth biting on) on just about every bone in the bloody skull, but some of them also have bones that essentially mimic teeth. I'm sorry if this sounds judgemental, but I have such a hard time understanding people who find science boring. This fish species has essentially "made" "false" teeth. If you find that boring, then I'm very sad for you.

Can anyone explain how evolution can account for two perfectly formed, shaped, and placed bone protrusions?

Natural selection.

Shape and position vary, and those with the best shapes and positions end up having the largest number of surviving fertile offspring because they were able to get the most food at the least expense.

Such bone spikes also occur elsewhere: Frogs lack teeth in the lower jaw*, so such spikes evolved several times independently, for example in hemiphractids. Then there are the magnificent pseudo-toothed birds…

* Except for the tree frog Amphignathodon, which really did get them back.

Not only do they put teeth […] on just about every bone in the bloody skull

Which leads me to another question: do cypriniforms lack all teeth, or just the marginal ones (those on the actual jawbones)? Because that, too, occurs elsewhere.

By David Marjanović, OM (not verified) on 11 Mar 2009 #permalink

Theodore:

Why only canine-like teeth and why only two?

Number of teeth is apparently not just two. See the pictures and especially what looks like some kind of scan (jazzed up X-ray?) image here.

By Stagyar zil Doggo (not verified) on 11 Mar 2009 #permalink

Who wins in a fight between Danionella dracula and a large octopus?

The article said this creature is 16mm long.

If so, not so scary as the photo makes it.

Which leads me to another question: do cypriniforms lack all teeth, or just the marginal ones (those on the actual jawbones)?

I don't know. I don't know that much about these guys. I'm more than happy to check into it, but it will take me a minute.

Oh, and:

Pseudo-toothed Birds!
Pseudo-toothed Birds!
Pseudo-toothed Birds!

Okay, I'm done now.

ONE! one vampire feesh! ah-ah-ahhhhh!

Cyprinids are food for real fish. Like cichlids. Not that I'm biased...ooh, I am!

Them's fightin' words, True Bob.

My RL surname is Lithuanian for 'Crucian Carp', so if you'd ever thought there was something fishy about that Brownian fellow...

Reminds me of my 2nd girlfriend. She's married now.

Stagyar zil Doggo: Thanks for the close-up image. That explains a lot. Without seeing the other "teeth" I was perplexed. I can see evolution factors producing teeth-like bones, making them sharp , and positioning them, but I couldn't understand why "only* sharp teeth evolved.

Proof of Evolution! Proof of evoltion! A fish with teeth?
No. I demand to see the followitg creatures, now. Else I'll ban science teaching in all the stupid states.
A fish with fur, to keep it warm.
A rat with radar.
A snake with nipples.
An amoeba with a penis.
A gay tree.
A poisonous black bird.
An ant with a built-in laser.
A true baby butterfly.
What other creatures would readers like to see, but can't because evoltion is false?
Oh, and there's a wink in there somewhere.

I am biased and think cypriniforms are quite awesome. The lab I work in studies the morphological novelties associated with the group, including the protrusible jaws. I wonder what sort of implications this has for the feeding with both the oral and the pharyngeal jaws (my area of interest). I'm thinking I am going to have to suck up to someone and try to get my hands on some of these fish.

milt:

Reminds me of my 2nd girlfriend. She's married now.

Presumably, ... to someone else.

The X-ray image in Ed's post (links in #22 and #23 above) appears to show the upper jaw as distinct from the skull, and possibly connected with a hinged joint in the middle. Is that indeed the case?

Also, what are the two openings (one circular and one oblong) just in front of and above the eye?

By Stagyar zil Doggo (not verified) on 11 Mar 2009 #permalink

A poisonous black bird.

They're black and orange and live in New Guinea.

Several species from different genera, too, all looking alike, convergent evolutes. Very cool.

And another thing we can't have:
A pig with X-ray vision!
Why? Becuase Darwin says we can't.
Well I can't wait to see all the cool creatures we'll get when evoluion is finally disproved!

Crows aren't *quite* poisonous, but they're darned close. Which is why nothing in its right mind eats crows.

AnthonyK

I so enjoy sitting back and seeing how my mind does not work.

If you didn't exist, we would have to invent you.

JC

JackC
Well, I don't and you did so there!
(insert blowing-raspberry emoticon).
Or vice versa.
I forget.

@31: Dr Evil's sharks, and a crocodaisy.

'You don't scare me with your fluffy white cat and this goldfish pond I am suspended over"

"You should be scared Mr Bond, those goldfish were crossed with Danionela dracula, Bwaaahaaahaaaa! Now DIE"

By Peter Ashby (not verified) on 11 Mar 2009 #permalink

@4: You fool, everyone knows that Lemmy is God!

The so-called X-ray is a cleared and stained specimen like that on PZ's home page. Red is bone and green is cartilage. If this is a male-only characteristic, then we are possibly talking contact organs. Contact organs are usually bony spines produced on scales, surface bones, boneless head areas, and fin rays in a number of minnow species males during breeding season. They occur in other fish groups as well. Find a picture of a breeding male stoneroller, Campostoma, for example.

By Jim Thomerson (not verified) on 11 Mar 2009 #permalink

I don't drink, Spine.

By antaresrichard (not verified) on 11 Mar 2009 #permalink

Maybe a primer in teeth evolution is in order. The evolutionary factors that produced teeth could be in play here.

I highly recommend Neil Shubin's "Your Inner Fish"

others have found it useful as well:

http://richarddawkins.net/article,2125,Fish-out-of-water-Your-Inner-Fis…

@David:

do cypriniforms lack all teeth?

no. In fact, they have often been classified via their pharyngeal teeth.

I've seen more recent evidence indicating that that method is now being displaced by molecular methods, though.

I wonder what sort of implications this has for the feeding with both the oral and the pharyngeal jaws (my area of interest).

have you seen any of the recent papers on how pharyngeal teeth can be modified by diet?

oh, and MY favorite fangfish is this one:

Anoplogaster

which is a midwater (around 400m) fish that is jet black, and actually typically comes up alive from deepwater trawls. I've been bitten by them several times; have teeth like needles. They are around 10-15 cm long typically.

PZ - your favourite lab animal is the zebrafish??? Now I really want to get that job I just applied for in a zebrafish lab.

AnthonyK @ #35:

You mean you haven't heard of the Kryptonian pig, Squee-El?

By Stardrake (not verified) on 11 Mar 2009 #permalink

Ichthyic @ 48,

"They are around 10-15 cm long typically."

The fish or the teeth?

John @ 54,
Thanks mate but I wasn't really confused.
I'm fairly certain Ichthyic wouldn't be gracing this comments page if the teeth of this Leviathan were 15cm long.

I'm fairly certain Ichthyic wouldn't be gracing this comments page if the teeth of this Leviathan were 15cm long.

holy crap! that thing would have put teeth all the way through my arm if they were THAT big!

lessee... the teeth are actually about 2.5cm long max (big enough, eh?) so if it had 15 cm teeth; to scale that beastie would be around a meter long!

something to actually be afeared of.

;)

btw, the unusual thing about anoplogasters is that they do typically come up alive from deepwater trawls, while most other deepwater fishes don't seem to make it.

they are also reflex biters, so that anyplace you touch them they will automatically flex their bodies such so they can sink their teeth into you.

having one a meter long?

no thanks!

Ichthyic @ 58

"having one a meter long? no thanks!"

Oh, I don't know. It'd fun to put a few in the lake at the Holy Land Experience theme park...

Neil Shubin's Your Inner Fish, chapter 4, has a fascinating section on Ostracoderms. They're primitive fish from 500 million years ago. Examine their skull closely:

... you find virtually the same structure as in our teeth. There is a layer of enamel and even a layer of pulp. The whole shield is made up of thousands of small teeth fused together. This bony skull -- one of the earliest in the fossil record -- is made entirely of little teeth.

Once upon a time, skulls were made of teeth!

By David Ratnasabapathy (not verified) on 13 Mar 2009 #permalink