On the more natural side of things, tiger sharks eat throughout the food web. One study found at least 192 different prey items in the stomach contents of tiger sharks from small shrimps and bivalves to various large whale species including sperm and humpback whales. Land animals aren’t safe either. Eight species of terrestrial mammals, including a blue duiker (small antelope), unidentified bats, an African porcupine, common mole rat as well as domestic goats and dogs were also recovered in a study. Given this it shouldn’t be too shocking that birds also make it into tiger shark diets. Birds increased in dietary importance with tiger shark body size.

A wide variety of miscellaneous items can also be found in their stomachs including: “junk food (e.g. sweet and potato crisp packets), terrestrial/flood garbage (e.g. condoms, chamois leather, cigarettes), and butcher’s bones (e.g. bags of chicken gizzards, cut abattoir bones).” There are also records of people finding strange items in tiger shark stomachs hundreds of years ago, like a bible (1792), an iron anchor (1804) and an unexploded bomb (1917).    

In an apparent first, recently scientists observed a tiger shark vomiting up a dead echidna whole off the coast of an Australian island.

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Connecting the oceans to land are numerous carbon highways.  These conduits bring food from land to the ocean, supporting an abundance of life.  Our group explores these carbon chains and explores some potential methods of carbon delivery to the deep.  Thus, alligators on the abyss.

At first it may seem fanciful that an alligator carcass might find its way to the deep.  However, dozens of species of alligators and crocodiles are found across the globe, in high numbers, and often in coastal areas.  Through either their normal migrating or foraging activities, or during flooding events, individuals may be found offshore in the ocean.  If one of those individuals meets an unfortunate end, it may fall to the seafloor.

In prehistoric times, the impact to the deep oceans could have been even larger, as large reptiles such as ichthyosaurs and plesiosaurs dominated the sea. Deploying a reptile in the deep sea today may reveal the animals that specialized on the carcasses of long-extinct ancient emperors of the sea.

Earlier this year, our research group placed three alligator carcasses 1.5 miles deep on the seafloor of the Gulf of Mexico in the first-ever alligator fall experiment.  Each of the three alligators met a different fate.

The first alligator had been on the bottom of the ocean for less than 24 hours. Despite the tough hide of the alligator, scavengers quickly got through and began to gorge themselves on the flesh of the alligator. Football-sized animals called giant isopods, relatives of rolly pollys or pillbugs, penetrated the hide in this short time-frame.  This demonstrates the speed and precision with which deep-sea scavengers can utilize any carbon source, even food from land and freshwater systems.

A little over 60 miles to the east of the first alligator, the second alligator had been sitting on the seafloor for a little over a month and a half.  All the soft tissue of the alligator had been removed by scavengers.  A small animal called an amphipod was still darting around looking for scraps, but the only thing that remained was a skeleton.  All of the soft tissue had been consumed. The spine curved just as it had been left.  A depression in the sediments indicated where the full body once laid.  The skull was turned over, likely by scavengers while picking at the flesh on the skull.

A fuzzy carpet covering the bones of the second alligator represented a brand-new species, previously unknown to science.  These zombie worms, or Osedax, colonize the bones of many types of vertebrates and consume the lipids within.  This was the first time zombie worms had ever been observed in the Gulf of Mexico or from an alligator fall.  They also demonstrate yet another pathway in which carbon from land makes its way into deep-sea food webs.

Another 60 miles east lay the third alligator.  It had only been eight days since it was laid on the seafloor.  As the camera panned to the marking device, a floating bucket lid attached to a rope like an underwater flag, it became clear that the alligator was missing.  All that remained where it had been dropped was an alligator-shaped depression in the sediments.  Drag marks in the sediment paved a path to what remained of the alligator fall.  An animal dragged this alligator 30 feet and left only the 45-pound weight and rope.  The rope had been bitten completely through. To consume an alligator, and create this disturbance, the animal must have been of great size.  We hypothesize that most likely a large shark, like a Greenland shark or sixgill shark, consumed this alligator whole.

Three alligator falls in the abyss met three very different ends, from being consumed by football-sized cousins of rolly polys, to zombie worms eating their bones, to a large shark dragging it away and consuming it whole.  This research has given us a glimpse into what impact large reptiles had in past oceans, as well as the role they play today.  It is clear that deep-ocean scavengers have no qualms about successfully and quickly consuming food that originated on land or freshwater.

Read more about this research in our group’s recent publication in PLOS One: “Alligators in the abyss: The first experimental reptilian food fall in the deep ocean.”

The post Alligators in the Abyss: Part 2 first appeared on Deep Sea News.

The post Experience the Life of the Deep Gulf of Mexico in 20 Videos first appeared on Deep Sea News.

The goal was to create a tree where the top represented the ocean’s surface and the base representing the abyssal floor. With a series of white, blue, and black ribbon and silver and blue miniature bulb ornaments, we created the effect of attenuated light as you move deeper. We wanted to make sure to include both a remotely operated vehicle on a lighted tether as well as lighted bathysphere. The tree also included a giant squid attacking a shark and whale fall complete with crabs and eels. We also made some tiny experimental wood falls to resemble the real ones we now have deployed all over the Gulf of Mexico.

You can print all of these decorations yourself. The complete collection can be found in my Thingiverse collection and include:

• The research vessel on top is the ICE – the icebreaker by vandragon_de (with the addition of little printed A-frame for the aft deck.
• The basic and blocky (or to sound like a sophisticated maker low-poly) remote operated vehicle was designed by us.
• Giant Squid by TheGreenFilament
• Shark! Sliced to Print by MacGyver
• Starfish model by Empiricus
• The Voyage of the Bathysphere by themindseye
• LOW POLY CRAB by RaffoSan (for whale fall)
• Eel by Benc (for whale fall)
• Whale by YahooJAPAN (whale for whale fall)
• Giant Deep-sea Isopod by the one and only Andrew_Thaler. (The model is actually based on a real specimen in our lab.)
• Puffer Fish (of awesomeness) by Dinoman (garland)
• A simple log by Montravont
• Vampire Squid by sinryan
• Hammerhead Shark by pmoews

The post 3-D Printing the Ulitmate Deep-Sea Christmas Tree first appeared on Deep Sea News.

Megalodon (Carcharocles megalodon) is the largest shark, at a magnificent maximum length of 18 meters (59 feet), to ever have dwelled in the oceans.  We know primarily about Megalodon’s existence through fossilized teeth.  Megalodon’s maximum size is inferred because we do not actually have a whole preserved Megalodon.  Using a mathematical relationship between body size and tooth size for Great Whites, we can estimate Megalodon’s size from its teeth.  In fact, my former graduate student Meghan Balk, with Catalina Pimiento, used this method with oodles of Megalodon teeth to show that Megalodon did not change much in size when it did exist.  But I digress.

A recent Twitter exchange made me realize that both some people think Megalodon still exists and a really good write up on how we know Megalodon actually does not exist is not on the interwebs. So in a numbered list, here we go.

No teeth. Sharks repeatedly shed and replace teeth. Go beach combing and you are likely to uncover teeth from sharks that dwell in the area.  We know about Megalodon primarily through fossilized teeth.  Although much to my amusement, fossilized poo, called coprolites, are also attributed to Megalodon.  A couple of vertebra columns have also been discovered.  These Megalodon teeth date from 23 million to 2.6 millions years ago.  After that, zero Megalodon teeth.  So if Megalodon existed now we would not only see Megalodon teeth all over today, as we do for other sharks, but with would have fossilized ones from the last 2.6 million years.  By the way, Megaldon teeth are pretty recognizable and distinctive, beyond just size, from other extinct sharks and the Great White. Researchers would not be confused if a tooth was from Megalodon.

No bite marks. Although much rarer than fossilized teeth, fossils also exist of whale bones with Megalodon tooth slashes and bites in them.  We have none of these type of fossils from the last 2.6 million years.  There is also no contemporary evidence from carcasses or bodies of whales of bite marks or wounds consistent with a large shark like Megalodon.

Not lurking in the depths. Everything we know about Megalodon suggests it was a large shark preferring tropical/subtropical warm waters.  Indeed, one hypothesis for its extinction was that the oceans got colder.  This warm temperature preference means that Megalodon is not hiding in the unexplored, deep and cold parts of the oceans that we have not explored.  Megalodon would literally be near the surface in plain sight.

Huge sharks exist: Huge sharks like sleeper, Greenland, basking, whale, Great White, and 7-gill are practically seen every day.  They all are very big and often mistaken for a Megalodon.  A group of colleagues and I actually researched how big some of these actually can get. But none of these are nearly large enough to come close to the estimated lengths of a Megalodon nor are their shapes consistent with what a Megalodon would like like.  Update: as noted below the largest known whale sharks actually do obtain Megalodon lengths.

Different oceans: The oceans with a massive ocean predator like a Megalodon would look a lot different structurally.  What do I mean?  Without going into all the specific science here, large predators have a huge influence on ecosystems and food webs, especially prey items.  When we look at ocean ecosystems and food webs there is no evidence that they could or do support a massive ocean predator. Again, one of the hypotheses for the extinction of Megalodon is that a changing ocean around 2.6 million years ago could not produce enough food for a massively-size carnivore like Megalodon.

1 Megalodon, 2 Megalodon, 700,000 Megalodon. For Megalodon to have existed 2.6 million years since the last known fossil tooth, there would need to be a sustainable population. Based on its size (you can see how this is done on my Kaiju post) we would expect global numbers, if we assume the largest Megalodon females get is 65.5 tons, of near ~700,000-1.5 million.  A lot of assumptions here.  Since we don’t have a relationship for shark abundance and size, I used the relationship for carnivorous mammals.  I also provide estimates for 50% (lower estimate) to 100% (higher) of the ocean being warm enough for Megalodon. Obviously this is crude estimate, but the point here is that there would be quite a few Megalodon in the oceans.  Now their numbers might be quite a bit less if Megalodon was going extinct.  But in the modern oceans, the primary way large marine animals go extinct is by human hunting.  Megalodon should be in nets and markets if this was the case.  Which brings me to my next point…

Underestimated commercial interests: If a 50-ton shark existed in the ocean, then commercial fishing operations would ensure Megalodon would have been found and on plates throughout the globe. Currently a pound of Mako is running $30 per pound. An average size Megalodon would bring in $3 million dollars at this price.

Fake documentaries and videos: Many people still think Discovery Channel’s fiasco of a media is real documentary.  It was not. Indeed, the original documentary actually had a too short and too hidden disclaimer.  Snopes has, as always, a great post about how this is fake.  Also the fake video of a Megalodon was actually a sleeper shark.

Government and scientific coverup:  I see this coverup language brought up a lot in discussions about climate change and other controversial topics.  I think this stems from a couple areas of misconception about how science is funded and how scientists interact.  Science is funded through multiple ways for scientists affiliated with universities, similar research institutions, or independents.  Government and corporate scientists are often funded by the institution and see more oversight.  Most funding for the former type comes from either foundations or the government.  You submit a grant and based on the quality, relevance, and importance of the proposed research you get might get funding.  This funding obviously dictates the larger theme of the research but does not dictate the findings, results, and conclusions of the research.  The concept of academic freedom, a scholar’s freedom to express ideas without risk of official interference or professional disadvantage, is by far one of the most cherished rights we have as scientists.  Many scientists would not work for institution or accept funding that would infringe upon this right.  I know of scientists who do research without funding even to pursue a course they are interested in.  Also, a government conspiracy to hide science would never be tolerated. Just look at the response from scientists to the current administration’s attacks and attempted cover up of climate science.  Second, there is no annual meeting where scientists meet to agree on what in the field to believe in or not.  Each scientist evaluates the evidence and data independently and draws the conclusions.  Consensus is reached when these scientists independently reach the same conclusion because the evidence is overwhelming.  Scientists actually thrive on disagreeing with one another.  Not about big things like if Megalodon went extinct or not, but why Megalodon went extinct.  I will finish by saying that if Megalodon still existed its discovery would greatly propel a scientific career.

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Happy Friday!

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Another year of science closes, giving us pause to review those new species of sharks described in the scientific literature, bringing the total number of known shark species to 512. Perhaps it’s a hollow victory to have so many different species known at a time when sharks populations worldwide are either in decline or in a complete population tailspin. But as taxonomists continue to kick ass and give names, our knowledge of shark evolution, biogeography, and ecology continue to get richer. Meet the new sharks of 2015:

Ginglymostoma unami, the Pacific Nurse Shark
This isn’t really the brand-spankin’ new species you might think, but it has been known for well over a century. The Nurse Shark (Ginglymostoma cirratum) had a disjunct distribution between the Caribbean and Gulf of Mexico and the eastern central Pacific oceans, meaning their range was divided into two separate populations. Like some nooks in the Ozarks, land barriers prevented gene flow, so the populations were both physically and genetically separated by a small spit of land called Central America. This team didn’t use genetic methods to test if the populations were distinct enough to be considered different species, but relied on a meristics, the process of compiling detailed measurements of the shark’s anatomy and comparing these values between the populations.  However, a 2012 paper on populations genetics of G. cirratum showed that the Pacific population was genetically quite unique, and divergent from any of the Atlantic populations. Since these two nurse shark populations had been separated by three million years, a few things can happen, like speciation. Indeed, their analysis showed that these two species are morphologically different enough to warrant giving the Pacific population its own scientific name. This name, G. unami, is an acronym of their alma mater, the Universidad Nacional Autonoma de Mexico.

Moral-Flores, L.F.D., E. Ramirez-Antonio, A. Angulo, and G. Perez-Ponce de Leon. 2015. Ginglymostoma unami sp. nov. (Chondrichthyes: Orectolobiformes: Ginglymostomatidae): una especie nueva de tiburón gata del Pacífico oriental tropical. Revista Mexicana de Biodiversidad 86 (2015) 48-58.

Scyliorhinus ugoi, Dark Speckled Catshark
Way down among Brazilians sharks once swam there in the millions, but overfishing took surely took a hefty toll, yet there are still new shark species to be found. Case in point: a new catshark that had long been swimming along most of the Brazilian coast but had been confused as other known species. Catsharks are a widespread, diverse, and somewhat confusing group of sharks. Differences in color, morphological changes between juveniles & adults, and sexual differences between males & females create difficulties in sorting out just how many species there are. Here, the authors use detailed meristic analysis to extract out a species that had been there all along, but the morphological features that delineate the species had not yet been defined.

SOARES, K.D.A. & GADIG, O.F.B. & GOMES, U.L. 2015. Scyliorhinus ugoi, a new species of catshark from Brazil (Chondrichthyes: Carcharhiniformes: Scyliorhinidae). Zootaxa, 3937 (2): 347-361.

Atelomycterus erdmanni, Spotted-belly Catshark

This sexy beast is one of the more colorful species of catsharks, and is one of several new species discovered from a larger taxonomic mess called the coral catsharks.  Using meristics, genetics, and biogeographical analyses, it turns out that the “coral catshark” represents several species, with this species as the newest. They don’t live in coral, so much as they crawl on and among coral reefs of Indonesia, using their pectoral and pelvic fins like tiny feet and walking like a more limber and agile salamander. Named after Mark Erdmann, a fish taxonomist who collected most of the known specimens, and was rewarded with this li’l shark bearing his name.

Fahmi & White, W.T.  2015. Atelomycterus erdmanni, a new species of catshark (Scyliorhinidae: Carcharhiniformes) from Indonesia. Journal of the Ocean Science Foundation 14: 14-27.

Bythaelurus tenuicephalus, Narrow-head Catshark
2015 also brought us two more catsharks, from the same genus, and both from the depths of the southwestern Indian Ocean. Hailing from the outer continental shelf of Mozambique and Tanzania comes the Narrow-headed catshark. The vast majority of sharks in recent years have been from the more remote pockets of Earth’s oceans, and in particular, from the deep oceans that have barely been explored. This species of Bythaelurus is a “dwarf”, a species that is sexually mature at a much smaller size than most other species in its genus.  The advantage of dwarfism might allow this species to breed at a younger age, thus increasing their overall lifetime reproductive output. Or it could be that being smaller simply means eating smaller prey that larger species of catsharks might miss. This sort of niche-partitioning may explain why there are so many different species of catsharks. The species name tenuicephalus means “narrow head”, a little less imaginative than some names, but descriptive nonetheless.

KASCHNER, C.J. & WEIGMANN, S. & THIEL, R. 2015. Bythaelurus tenuicephalus n. sp., a new deep-water catshark (Carcharhiniformes, Scyliorhinidae) from the western Indian Ocean. Zootaxa, 4013 (1): 120–138.

Bythaelurus naylori, Dusky Snout Catshark
Another year, another catshark on the list.  This species however, has quite an interesting story behind its capture.  Massive trawlers, towing huge nets and pulling up tons of fish aren’t new, but what is new is the trend for these huge vessels to move from depleted fishing grounds in the shallows, and into the relatively untapped fishery resources of the deep sea. In addition to the targeted commercial species that will earn them great sums of money when they return to port, these nets also catch and kill tons of other non-marketable species.  This is what ecologists call ‘by-catch’, but there is a sunny side to such needless destruction.  Commercial vessels are often the first to explore deep-sea zones, well ahead of research cruises that are difficult to fund and even more impossible to sustain over time. If you can get onto one of these factory trawlers, the bounty of the bycatch is yours, and what a paradise this is to shark researchers. Dave Ebert & Paul Clerkin of the Pacific Shark Research Center at Moss Landing Marine Lab got the invite to board one of these vessels as it sailed south from Mauritius, but with a small catch: they had to stay for the entire three month trawling season. If you haven’t ever had the displeasure of sailing the wild waves and howling winds where the Indian Ocean meets the Southern Ocean, then you wouldn’t know that it makes The Deadliest Catch look like a Honolulu harbor cruise. Already hardened by the seas of the Gulf of Alaska, Paul made three of these cruises, collecting more than a dozen new species of skates, rays, sharks, and chimeras that will be published in future years. The species name naylori honors Gavin Naylor of the College of Charleston who, through genetic analysis, is compiling a more complete evolutionary history of extant shark species.

EBERT, D.A. & CLERKIN, P.J. 2015. A new species of deep-sea catshark (Scyliorhinidae: Bythaelurus) from the southwestern Indian Ocean. Journal of the Ocean Science Foundation 15:53-63.

And lastly….
Etmopterus benchleyi, Ninja Lanternshark
If you haven’t already seen this sassy new deepsea shark that went viral late last year, check it out here, and here, and here. That makes six new sharks for 2015, but new species will be discovered and described in 2016, so check back next year.
VÁSQUEZ, V.E. & EBERT, D.A. & LONG, D.J. 2015. Etmopterus benchleyi n. sp., a new lanternshark (Squaliformes: Etmopteridae) from the central eastern Pacific Ocean: Journal of the Ocean Science Foundation; 17: 43-55.

The post Meet the New Sharks of 2015 first appeared on Deep Sea News.

Discoveries in science are not often the result of the stereotypical and unrealistic step-by-step scientific method, but usually occur through other more mundane and unexpected routes.  Think of Flemming’s moldy lunchbox sandwiches as the pathway to developing penicillin, or Newton stone-drunk in an orchard contemplating gravity with a rain of apples falling on his noggin’. When marine biologists discover a new species, especially a new shark species, it isn’t the result of putting on a red-knit cap and a pair of Speedos on your research vessel and loudly declaring that you are going to discover a new shark. Throw the mini-sub overboard, gaze into the darkness through an oval window, and bam – a new species is discovered. Bottles of Clicquot pop back on deck, the scientific community hoists you on their shoulders and applauds your excellence in zoology. Maybe the jackals from Shark Week give you a call to recreate your daring feats for a documentary low on facts and ripe with pseudoscience, likely replacing you with younger C-list actors and warping what actually happened with their own overly-dramatic narrative. With our discovery of the newly-described Ninja Lanernshark, it wasn’t the reward of a planned grand adventure, but was the usual meander of social connections, cooperation among colleagues, the benefits of museum archives, hard work from unpaid graduate students, and plain old good luck.

Several years back, John McCosker of the California Academy of Sciences and Dave Ebert, also a Cal. Academy research associate like myself, and I were studying chimeras, distant deep-sea cousins of sharks. One day I got an email from D. Ross Robertson of the Smithsonian Tropical Research Institute who in 2010 chartered a Spanish trawler and conducted a number of deep-sea collections off the Pacific coast of Central America, and among the barrels of specimens he collected were a few odd-looking chimeras he wanted us to identify.  Ross had the good sense to photograph many of these specimens while they were still fresh out of the nets, and he forwarded them to us. Along with the photos of these chimeras were hundreds of other photos of deep-sea fishes, including sharks, skates, and bony fishes that were either entirely unknown species, or new locality records for previously-known but poorly documented species.  To a deep-sea ichthyologist, this was the jackpot.  I soon headed to the ichthyology collections at the Smithsonian and spent several days pulling these specimens out of gallon jars of ethanol or dipping my arms nearly shoulder-deep into huge vats of the stuff where the large specimens were preserved. Taking photographs, measurements, and making on-the-spot identifications, I compiled a large number of specimens that the fine folks in the Smithsonian ichthyology department shipped back to the California Academy of Sciences where we could more closely study them.

Once the sharks arrived, Dave and I looked them over and we both thought they were a new species since
they were unlike anything yet known from the eastern central Pacific, but “discovering” a new species isn’t as easy as that.  To describe a new species you need to conclusively show the range of variation in your new species is outside the range of variation in previously-known species. It has to be significantly different than any relative species thus far known. To do this required the painstaking and time consuming process of morphometrics, the detailed series of measurements of the sharks anatomy, and meristics, the count of such things as vertebrae, tooth rows, number of dermal denticles, etc. Fortunately, Dave and I already had a process where we worked with young go-getters, mainly his graduate students at the Pacific Shark Research Center in the Moss Landing Marine Laboratory, to learn the process of describing and publishing new species of sharks, rays, and chimeras. Victoria Vasquez was one of his students already with experience in shark ecology and conservation outreach, so he assigned her to heading the job of the not-so-sexy nitty-gritty of the detailed analysis of the formalin-preserved shark specimens with microscopes, rulers, and dial calipers, and she was a superstar at it.

It soon became clear that these small sharks did indeed represent a new species of lanternshark, a family of deep-sea sharks with this as the first species yet known from the region.  Most deep-sea sharks are dark brown or black to blend in with the darkness of the depths, but some species, like the lanternsharks, have bioluminescent organs that glow a shining pale green. This adaptation may either be to attract mates, maintain group cohesion in a school, lure smaller invertebrates within snapping range of their mouth, or possibly to create a halo-like effect to mediate the downwelling light from above and the tell-tale shadow a predator might see from below, making them effectively invisible. The newly described Ninja Lanernshark seemed to have few of these glow-in-the-dark organs, appearing less like a shark jack-o-lantern and more like a Japanese ninja dressed in black, and using their dark visage to their advantage, so prey may never see it coming. When Victoria consulted her young cousins to help with a common name for this new species, there were many options from the excited shark-loving kids, but Ninja Lanternshark, honed down from Super Ninja Shark, seemed appropriate.

The scientific name was of course in honor of Jaws author Peter Benchley. Several decades earlier I worked with him during a shark conservation program through the Cal Academy, and he admitted – what I had already heard through many other people – that he carried a burden of regret for the violent backlash against sharks unintentionally instigated by his book.  For years afterward, he was not just an advocate for sharks, but a tireless campaigner in promoting ocean conservation. Long after his death, the Benchley Awards fund those who share his dream. Coincidentally, this year was the 40th anniversary of the publication of Jaws, and Victoria already knew Benchely’s widow, who was told about the new shark bearing her husband’s name. After several months of measurements, comparisons with other known species, and countless revisions of the manuscript, it was submitted to the Journal of the Ocean Sciences foundation, one of the rare but essentially important journals that still publishes species descriptions of fishes, and more importantly, one with open access, making this shark species immediately available to the world just this week. The ‘discovery’ of a new species of shark means nothing until a detailed, peer-reviewed study is finally made public.  Fortunately, the bottles of Clicquot can still be popped.

Vasquez, V.E., D.A. Ebert, and D.J. Long.  2015. Etmopterus benchleyi n. sp., a new lanternshark (Squaliformes: Etmopteridae) from the central eastern Pacific Ocean. Journal of the Ocean Sciences Foundation, 17:43-55.

The post Ninja Lanternshark: the New Shark Species You Will Never See Coming first appeared on Deep Sea News.