When two become one (for real)

The deep sea anglerfishes of my previous post are famous for their strange reproductive habits. These habits are strange because they are much more similar to the feeding habits of most other organisms. In the early 1900's, biologists started finding female deep sea anglerfishes with tiny fish attached by their snouts to the females' bellies. Sounds like those poor ladies were getting eaten, right?

Nope, it turns out that those tiny fish were the men in their lives. When I say tiny, I mean that in the most extreme species, the females can be more than 60 times the length and about a half a million times as heavy as the males. These males look nothing like the intimidating females--the anglerfishes you're thinking about, with large jaws and lures for catching prey. The males have neither large jaws nor lures: the only thing large about them is their nostrils, which helps them to find a female in the dark depths of the sea. In some species, once the male finds a female, he attaches permanently to her, becoming embedded in her mass. Their tissues fuse together, and even their blood circulates together. He becomes completely dependent upon her for nutrition, living effectively as a parasite, waiting to provide sperm when she decides to spawn. In some species, the females take on just one male, but in others, females can absorb up to eight.

Unfortunately I don't have any photos to post***, but in reading up about this I stumbled upon some historical quotes that are too good not to share.

This quote is from C.Tate Regan, who, in 1925 was the first to conclude that the tiny fish attached to the females must be males. He romanticizes the phenomenon to the point that it almost, perhaps, maybe, possibly, sounds ... beautiful? If anyone needs an eccentric quote for a toast at an upcoming biologist's wedding, here ya go:

[The male fish is] "merely an appendage of the female, and entirely dependent on her for nutrition, ... so perfect and complete is the union of husband and wife that one may almost be sure that their genital glands ripen simultaneously, and it is perhaps not too fanciful to think that the female may possibly be able to control the seminal discharge of the male and to ensure that it takes place at the right time for fertilization of her eggs."

Then there is this quote, from William Beebe, writing in 1938. He, on the other hand, makes the phenomenon sound, well, utterly terrifying:

"But to be driven by impelling odor headlong upon a mate so gigantic, in such immense and forbidding darkness, and willfully to eat a hole in her soft side, to feel the gradually increasing transfusion of her blood through one's veins, to lose everything that marked one as other than a worm, to become a brainless, senseless thing that was a fish--this is sheer fiction, beyond all belief unless we have seen the proof of it."

 And proof of it, indeed, he--and many others--have seen.

*** We do have a female specimen with a parasitic male attached, but it's been used for teaching so much that it's in danger of falling off, so I didn't want to risk making it worse by taking it out to photograph it. Sigh...


Sources:

Pietsch, Theodore W. 1976. Dimorphism, Parasitism and Sex: Reproductive Strategies among Deepsea Ceratioid Anglerfishes. Copeia, No. 4, pp. 781-793.

Pietsch, Theodore W. Ceratioidei. Tree of Life Web Project.

Pietsch, Theodore W. 2009. Oceanic Anglerfishes: Extraordinary Diversity in the Deep Sea. Berkeley and Los Angeles, University of California Press.

Tiny but Monstrous Type Specimens from the Deep

One of the greatest things about our type collection of fishes is that most of them are deep sea fishes! And the reason we have all of these deep sea types is an unlikely story: it's in large part thanks to the efforts of -- not any scientist or scientific organization -- but an independent New York businessman named Harry Payne Bingham. Bingham was a curious guy who, in the 1920's, developed a serious interest in marine biology. So, of course, upon developing this interest, he hired a biologist, a few assistants, and even an artist, and he set sail exploring and collecting fishes in his own yacht, the "Pawnee." I say we need more businessmen like that! :)

The Pawnee sailed three times, in 1925, 1926, and 1927, and after this last expedition, Bingham donated all the specimens of his "Bingham Oceanographic Collection" to the Peabody Museum. Many of his specimens were new to science, hence all of our type specimens.

Here are some excerpts from an article published in the Yale Alumni Weekly in 1928 that convey the excitement of these discoveries at the time:

"Mr. Bingham is to be congratulated on the success with which he has carried out thus far his venture in studying marine life. Few men have combined the means, the foresight and the inclination to undertake such work.... A natural desire to preserve some of the fishes he found in tropical waters increased his interest in ocean life, leading to expeditions which have yielded invaluable returns to science."

Bingham apparently even acquired a novel, giant, high-tech net for use in the third expedition:

"The third expedition, by far the most successful judging it by the importance of its results to science, visited the waters about the Bahama and Bermuda Islands. Mr. Bingham had come more and more to appreciate the value of deep-sea investigations, and had included in the equipment of the "Pawnee" a specially constructed circular net fourteen feet in diameter at the opening. This was probably the largest net of its kind ever used in deep-sea collecting, and proved its worth by capturing a great many new of little known free-swimming organisms between the depths of 3000 and 6000 feet. Remarkable indeed are the bizarre fishes preserved from the hauls of this net. Thirty new species have already been described by Mr. Alfred E. Parr, whom Mr. Bingham had engaged as oceanographer for this cruise. As many more will probably be found."

Those thirty new species, however, only included those in the third expedition! Regarding the entire collection resulting from all three Pawnee trips, the author, Peabody curator Stanley Ball, writes:

"The hundreds of these fishes now deposited in Peabody Museum, preserved in alcohol and formalin, constitute one of the country's most extensive and valuable deep-sea ichthyological collections... The entire collection of fishes at present time requires about 3000 catalogue numbers. Not less than one hundred new species, as well as many rare forms, are included. The larval eels alone would gladden the heart of any ichthyologist..."

OK but enough history already. Now for some of these deep sea types! These are anglerfishes of the family Linophrynidae. I think all the anglerfishes are awesome, but these are double awesome. All anglerfishes have an appendage on top of their heads known as the esca-- it's a fleshy growth that derives from their first dorsal spine which harbors symbiotic bioluminescent bacteria, and it acts as a lure. But most Linophrynid anglerfishes have this esca AND another appendage- a "complex bioluminescent chin barbel." Out of their anglerfish relatives, they also have  the largest mouths, "with the longest dagger-like teeth of any fish and perhaps of any vertebrate."

Here are some of these spectacular Linophrynids. This is the holotype of Linophryne coronata diphlema, described in 1934 by Albert Parr. It has a chin barbel longer than its body length! It was collected near New Providence Island in the Bahamas:

This is the holotype of Linophryne brevibarbis, described by Parr in 1927. It was collected off Bermuda with that famous 14 foot circular trawl!

And here is the holotype of Linophryne arborifer, also described by Parr in 1927. It was collected off Bermuda, again with the 14 foot circular trawl:

These guys all look pretty scary, but as I alluded to in the title, each one is actually only about the size of a nickel.


Source:

Pietsch, Theodore W. Linophrynidae. Tree of Life Web Project.

Type specimens: Will the real slim [insert species name here] please stand up?

I've spent the past month or so re-curating our type collection of fishes and I just finished! This was great fun given the importance of type specimens in biology. A type specimen is the "name bearer" for a given species. That is, when a biologist discovers and describes a new species, he or she designates a single specimen to be the official representative of that species. As alluded to in the title of this post, I always think about the Eminem song The Real Slim Shady when I think about type specimens: if anyone ever wanted the "real" entity for any species to figuratively stand up, a biologist would go fetch you the type specimen. We designate type specimens this way so that if future researchers, for example, find an individual or a population that is similar to a known species but they suspect might be a new species, there is no question about which specimen of the known species they should compare it to. Type specimens are always the reference point when making any species updates and revisions.

Species updates and revisions actually happen more often than one might think! Systematic biologists (those who study life's diversity) are constantly acquiring new data that can lead them to discover that one species is really multiple species (this is called splitting), or to discover that groups that were thought to be different species are really only one (this is called synonymization, or lumping). Then of course there are always the discoveries of entirely new forms previously unknown to us humans, which are perhaps the most exciting type of update...

The changing nature of species boundaries (like that of scientific knowledge in general!) actually made cataloging and labeling our type collection an interesting job. Some species designations have stood the test of time. For example, we have the type specimen for the vermiculate electric ray, Narcine vermiculatus. It was originally described as Narcine vermiculatus in 1928 by Charles Breder, and today the species represented by this type specimen is still known as Narcine vermiculatus. Here's our type specimen:

On the other hand, some species names have not stood the test of time. For example, we have the type specimens for a dragonfish that was described as Flagellostomias tyrannus by Albert Parr in 1927. Here is one of them:

This species was synonymized with (shown to be the same species as) Flagellostomias boureei, in 1964 however, so any specimens that were once considered Flagellostomias tyrannus are now considered to be Flagellostomias boureei.

Our usual practice for labeling specimens in the collection is to label specimens with their current valid name. But these type specimens are well, special. No matter how the species is reclassified, the type specimen for a particular name will always be the type specimen tied to that name. And with new data, a  species name that has become invalid could be come valid again. So it's essential to preserve the linkage between the type specimen and its original name.

So here's the label template we made to solve this little dilemma -- that is, whether to label our types with the current name, or the original name. We labeled them with the original name in bold, and the current name designated underneath:

This works especially well because we keep our type specimens in their own section of the collection, not interspersed with the rest of the specimens.

It turns out that here at Peabody Vertebrate Zoology we have one of the largest ichthyological type collections in the United States and Canada (Poss & Collette 1995). Pretty cool, huh? For the next few posts I'll be featuring some of my favorites.


References:

Poss, S.G. and B.B. Collette. Second Survey of Fish Collections in the United States and Canada. Copeia 1995: 48-70.

Not-so-flabby flabby whalefishes

So this specimen first caught my eye because it belongs to a family of deep sea fishes known as the "flabby whalefishes" (Cetomimidae). But .... this little fish, caught off the coast of Portugal in 1959, was neither flabby, nor was it whale-y. To my eye at least. I found this pretty amusing in and of itself.

YPM ICH 4899

But THEN... I discovered that when alive, it is PINK! It so happens that I'm not really even much of a pink fan myself, but this species, Cetostoma regani, is bright pink as bright pink gets. (And its common name is the pink flabby whalefish. Fancy that.)

Photo from the MCZ

And THEN... upon further googling, I learned that in 2009, this species played a big part in an amazing story of scientific discovery. The story goes like this:

Once upon a time, there were three fish groups, the tapetails (Mirapinnidae), the bignoses (Megalomycterydae), and the whalefishes (Cetomimidae). They were all very funny-looking and lived in the deep sea. But they all looked wildly different, so --as one would expect--they were considered to be three families.

But in 1989, ichthyologist John Paxton noticed that, strangely, all of the known specimens of whalefishes were females. Similarly, biologists soon noticed that all of the known specimens of bignoses were males. And all of the known specimens of tapetails were sexually immature...

Following these clues, a team of biologists, headed by David Johnson of the Smithsonian, recently sequenced the DNA of specimens from these three families and found that the DNA from each was essentially identical.  These were not three families--they were only one! Consistent with the clues, they are simply different life stages of the same fish. The tapetails are the larvae, the bignoses are the males, and the whalefishes are the females. Pretty amazing. Here's a picture of all of the families:

Image taken from here.

The degree of morphological difference between the larval and adult stages, and between the males and females, is truly remarkable. The authors of the study in 2009 note that although significant larval transformations occur in some other deep-sea fish families and extreme sexual dimorphism is common among vertebrates, "the extraordinary combination of both ... for the whalefishes is unparalleled within Vertebrata." And if there was any doubt about their findings, the team found morphological evidence to back up the DNA evidence. They were able to identify some transitional specimens-- that is, female "tapetails" transitioning to the "whalefish" stage, and male "tapetails" transitioning to the "bignose" stage.

Note that the whalefish at the bottom of the image above looks much more whale-y than the specimen I re-curated! Perhaps our specimen is in fact a transitional specimen ... 

For more details on the story, check out this interactive Smithsonian website about the discovery.


References:

Johnson, G.J. et al. 2009. Deep-sea mystery solved: astonishing larval transformations and extreme sexual dimorphism unite three fish families. Biology Letters 5: 235-239.

Shiny-buttoned Midshipman Fishes

A few months ago, I re-curated these specimens. They had funny dots lining their entire bodies, like so:

YPM ICH 8902

It turns out that these dots are photophores, which are little organs that produce light (often referred to as bioluminescence). The fish belong to a genus named Porichthys, and they're actually part of the same family, Batrachoididae, as the Oyster Toadfish from two posts back. The 15 species that make up the genus Porichthys are commonly known as Midshipman Fishes, because the 700+ photophores that adorn their epidermis are said to resemble the gleaming buttons of a naval uniform.

Here is a photo of a very fine human midshipman* specimen, Jack Vine, a childhood friend of mine, pictured here in full naval uniform with his proud mom:

And here is a photo of a bioluminescent midshipman fish specimen:

Photo taken from this website

I wonder if the person who first noticed the fishes' midshipman likeness was looking at the two rows of pores lining the anal fin (starting at the middle of the fish and continuing to the tail). To me, those two rows really jump out as resembling the naval uniform buttons:

YPM ICH 8902

I think that the clean, tapered lines of the midshipman fishes, as shown well by this sketch, also contribute to their overall resemblance to the naval uniform:

Image from NOAA

Why do the midshipman fishes have these photophores? That... is a good question. A number of functions have been hypothesized. One hypothesis is that they function to aid in prey capture. The idea here is that the Porichthys pattern of luminescence mimics the light of a small swarm of krill (Tsuji et al 1971). This might allow the midshipman fishes to approach such a swarm undetected and then easily feed on them. Or perhaps this sort of mimicry could even lure the krill swarms to the fish. As far as I could find though, this hypothesis hasn't really been tested.

Another hypothesis is that the photophores function in something known as "counterillumination." This is a form of bioluminescent defense against predators that is used in many types of organisms, including crustaceans and various fishes. Essentially what happens is that an organism using this "counterillumination" will use photophores on its underside to match any dim light coming from the surface of the water. In so doing, they can make a potential shadow disappear and thus camouflage themselves. This hypothesis has actually been tested and supported! It's been showed in laboratory experiments that midshipman fishes can match the intensity and color (among other things) of downwelling light (Harper and Case 1999). This hypothesis also makes intuitive sense because most of the photophores are concentrated on the bottom of the fishes-- where they would need to be for counterillumination.

One last hypothesis is that the glowing photophores function in courtship (Crane 1965). Various authors have expressed skepticism about this hypothesis, however, because there is a population of midshipman fish in Puget Sound, Washington, that has no luminescence capability, yet they still live and reproduce successfully. If the photophores were necessary for courtship, the Puget Sound population shouldn't exist (Warner and Case 1980).

How do midshipman fish get their ability to glow? By eating tiny bioluminescent crustaceans called ostracods. Without ostracods, the midshipman fishes' photophores are useless. This is where midshipman fishes get luciferin, which is a compound that bioluminescent organisms need to emit light. Many organisms produce luciferin on their own, but others, like the midshipman fishes, have to acquire it through their diet. It was actually the Puget Sound population of midshipman fishes that clued scientists in to the fact that midshipman fishes get their luciferin from ostracods. It turns out that the Puget Sound population has no luminescence capability because the there are no bioluminescent ostracods for them to eat there (Warner and Case 1980)! They can easily luminesce, however, if they are fed the proper ostracods.

Ostracod

Oh, one more thing before I sign off. Just like the toadfishes, the male midshipman fishes also make humming sounds with their swim bladders! (Like I mentioned earlier, the midshipman fishes are part of the same family as the toadfishes). Instead of people living on the east coast though, it's the people in San Fransisco Bay who are kept awake by their mating calls. You can listen to them hum on this little feature by NPR.

And here's one last picture of one of our specimens, species Porichthys porosissimus, collected in the Gulf of Mexico off Galveston, Texas, in 1932 by the vessel Mabel Taylor.

YPM ICH 8900

*I should note that Jack is no longer a midshipman, although I think he was when that photo was taken. He graduated from the Naval Academy in 2008 and is now a fully commissioned Navy pilot serving in the Middle East.


References:

Crane, J. M., 1965. Bioluminescent courtship display in the teleost Porichthys notatus. Copeia, 2 : 239-241.

Harper R.D., Case J.F. 1999. Disruptive counterillumination and its anti-predatory value in the plainfish midshipman Porichthys notatus. Mar. Biol. 134: 529–40.

Tsuji F.I., Haneda Y., Lynch III R.V., Sugiyama N. 1971. Luminescence cross-reactions of Porichthys luciferin and theories on the origin of luciferin in some shallow-water fishes. Comp Biochem Physiol 40A: 163-179.

Warner J.A., Case J.F. 1980. The zoogeography and dietary induction of bioluminescence in the midshipman fish, Porichthys notatus. Biol Bull mar biol Lab, Woods Hole 159: 231-246.

Happy Valentine's Day! Rock-paper-scissors, anyone?

Forget about love, flowers, chocolates, teddy bears, etc. etc. Common side-blotched lizards decide on their Valentines by playing rock-paper-scissors. True story.

Here are three specimens of this species, Uta stansburiana, from our collection, HERR 7589, 7594, and 7595, collected in Texas in 1971:


So the way this crazy love (or not... love...) game works is like this. Male common side-blotched lizards come in three different forms. There are orange-throated males, yellow-throated males, and blue-throated males. Here's a pic, taken from the website of Barry Sinervo, one of the biologists who first figured out the rules of this lizard's game.


Orange-throated males are largest and the most aggressive of them all and as such they're able to defend large territories with lots of females in them. They can easily overpower the blue-throated males, which are of a medium build.

Orange-throated males cannot defend against yellow-throated males, however. Yellow-throated males are the smallest of them all and look like females! Given this, they're able to sneak into the territories of orange-throated males unnoticed and mate with any of the females there who might be tired of bloated orange-throated machismo.

The stealth strategy of the yellow throats is powerless, however, against the medium-size blue-throats. The blue-throated males keep small territories and work together to guard their females. As a result, the yellow-throated males can't fool the watchful blue-throats like they can with the orange-throats.

So to sum up, orange beats blue, blue beats yellow, and yellow beats orange. Pretty cool if you ask me.

The success of these different mating strategies depends on the the rarity of each form in a given population. For example, if there are too many yellow-throated males, their "sneaker" strategy becomes ineffective, because well, it's not very sneaky anymore if everyone is doing it, too. So the prevalence of any given form will cycle every few years in a given population of common side-blotched lizards. In some years, there will be more blue-throated males, other years more orange-throated males, and in other years, more yellow throated males. When one form becomes too common, the others start to be more successful.

Sources:

Sinervo, B. and Lively, C.M. 1996. The rock-scissors-paper game and the evolution of alternative male strategies. Nature 340:240-246

Corl, A., Davis, A. R., Kuchta, S. R., Comendant, T. and Sinervo, B. 2010. Alternative mating strategies and the evolution of sexual size dimorphism in the side-blotched lizard, Uta stansburiana: a population-level comparative analysis. Evolution 64: 79–96.

Singing Toadfishes in Space

Like the Lizardfishes from a few posts back, here is another fish family named for a land-dwelling look alike. The toadfishes make up the family Batrachoididae and are benthic ambush predators that use their ugly appearance for camouflage as they lie in wait for their prey. They're quite hardy creatures, too! Some individuals have remained alive for more than 24 hours out of the water (Paxton and Eschmeyer 1994).

Here are some pictures of YPM 8923, species Opsanus tau, collected on October 6, 1932, off of Long Island, NY:





The most interesting thing about toadfishes, I think, is that they are known for their singing. During mating season different toadfish species produce a variety of sounds using their swim bladders. Opsanus tau in particular produces a loud "boatwhistle" sound that is famous for keeping people living near the shores of North America's east coast awake (Paxton and Eschmeyer 1994). It's no wonder that they make such a loud noise, too-- the muscles in their swim bladder that contract to make this noise are the fastest contracting vertebrate muscles known (they contract at a rate of 200 Hz). The next fastest muscles known are those at the base of the tail in rattlesnakes, and they only contract at half the rate of Opsanus tau's (Rome et al. 1996).

And yet another interesting fact about species Opsanus tau-- NASA has sent a bunch of these guys to space! NASA scientists use them to perform experiments designed to better understand balance disorders that affect astronauts in space. Why toadfishes for this task? The structure of their inner ear--the place that helps control balance--is very similar to ours, making it a good model organism. Who would have thought...


References:

Paxton, John R., and W.N. Eschmeyer. 1994. Encyclopedia of Fishes. Academic Press, San Diego.

Rome L.C., D.A. Syme, S. Hollingsworth, S.L. Lindstedt, and S.M. Baylor. 1996. The whistle and the rattle: the design of sound producing muscles. Proc Natl Acad Sci USA 93:8095-8100.