Meet your distant relative, Entelognathus primordialis, possibly the first earthling with a face. Or at least a familiar face.

Entelognathus primordialis (where Entelognathus means “complete jaw”) is described this week in Nature. Discovered in a quarry in China, the remarkably well-preserved fossil is somewhat 3D, displaying a modern type of jaw.

E. primordialis is a placoderm, an early class of fish that lived 430 to 360 million years ago. These fish were covered with an armor of bony plates and gave rise to two later groups—bony fish and cartilaginous fish.

The evolution of jaws is one of the key episodes in the evolution of vertebrates, but the gap between jawed and jawless vertebrates is so large that it has been hard to work out the individual evolutionary steps in the transition. Min Zhu and his colleagues hope to make the link with E. primordialis.

The 419 million-year-old fish fossil has jawbone features previously restricted to bony fishes, but has the full body armor seen in placoderms. It would have been around 20 centimeters (eight inches) long.

Prior to this recent find, most scientists agreed that placoderms had no jaw and were more similar to the cartilaginous fish, like modern day sharks, while the bony fishes are believed to be our ancestors. According to Nature News:

Such fishes went on to dominate the seas and ultimately gave rise to land vertebrates.

In addition to facing off with placoderms, the new study puts cartilaginous fishes into a whole new light—perhaps they are even more evolved than previously thought.

Last fall, Science Today’s Barbara Tannenbaum caught up with Dave Ebert and his grad student, Paul Clerkin, as they brought deep-sea shark specimens from the Indian Ocean to their new home in the Ichthyology collection here at the Academy.

Tannebaum’s article, “Fantastic Voyage,” captured their work expanding the Academy’s collections, and Ebert, an Academy research associate and director of the Pacific Shark Research Center in Moss Landing, has been tirelessly working ever since. We caught up with him by phone this week to hear the latest.

Earlier this year, Ebert traveled to Mauritius, east of Madagascar, searching for new and unknown shark species in the Indian Ocean. Ebert also attended a workshop put on by the Food and Agriculture Organization of the United Nations, or FAO.

“We’re working on an identification catalog for sharks in that area to understand what’s being caught there,” Ebert explains.

In May, Ebert was part of a research cruise off of New Zealand, seeking more undiscovered sharks. His work was captured on film by the BBC for a segment that will air in early 2015. They hope to film him more on other expeditions in the coming year, too. “They’re doing something a little different,” Ebert says. “Kind of a day in the life of a researcher. They send us to a couple of different places to do some field surveys that will likely result in finding new or lesser known species.”

Ebert is pleased with the upcoming documentary because he’s hoping it will bring public awareness to little known shark species. “Everyone knows the white sharks and hammerheads, the charismatic species. These high profile sharks get a lot of attention and protection. But there are a lot of other species out there that for whatever reason are not known. Some of these have much higher conservation needs.”

He mentions the honeycomb cat shark (Holohalaelurus favus) off east Africa. The species was very abundant in the 1950s and 1960s, but hasn’t been seen for 40 years. “The shark didn’t even have a formal scientific name until 2006,” Ebert says. “We should know more about sharks like these and look out for them in fishery by-catch.”

When Ebert isn’t traveling, he works tirelessly on naming and describing these unknown and recently discovered shark species. The sharks he and Clerkin discovered were shipped here to the Academy for further examination. They will also find a permanent residence in our collections. “Several specimens just arrived from Taiwan and several more are due from South Africa this week,” he says.

Speaking of South Africa, Ebert will be a keynote speaker at next year’s Sharks International Conference in Durban, South Africa. The event occurs once every four years, and Ebert will be presenting on the biodiversity and conservation of sharks and rays, mostly African species.

And for true shark fans out there, Ebert is lead author on a new guidebook, Sharks of the World, due out next week.

Ebert is a busy scientist with much work ahead in discovering, describing and protecting sharks. Stay tuned for more updates on his important work.

Remoras could be classified as freeloaders, having evolved sucker discs on the top of their heads, which they use to attach themselves to their hosts. They hitch a ride on sharks or other large marine animals (rays, whales, turtles), even though they are fine swimmers on their own. They also eat the leftovers or possibly the feces of their host animal. Living on a large animal also protects remoras from predators.

Remoras cause no damage to their shark host, who don’t get much back from remoras, unless sharks find amusement in their oddly upside-down disc-shaped heads. Remarkably, these suckers evolved over time from the fishes’ dorsal fins.

Two recent studies, looking at a fossil remora and remora larvae, have determined how these fins develop over time into a strong sucking device.

The first study, led by Oxford University’s Matt Friedman, examined a 30 million year-old early remora fossil with a fully functioning sucker on its back.

“The remora sucker is a truly amazing anatomical specialization but, strange as it may seem, it evolved from a spiny fin,” Friedman says. “In this fossil the fin is clearly modified as a disc but is found on the back of the fish. It enables us to say that first fin spines on the back broadened to form wide segments of a suction disc. After the disc evolved, it migrated to the skull, and it was there that individual segments became divided in two, the number of segments increased, and a row of spines were developed on the back of individual segments.”

The second study looked at the development of remora from the earliest larval stages and compared it to the larval development of white perch, fish that have typical dorsal fins.

The research team found that up to a certain stage in the fish’s development, the dorsal fin develops in the same way and looks very similar in both fishes. Then, through a series of small changes, the remora’s dorsal fin begins to expand and shift toward the head. By the time the remora has reached about 30 millimeters (1.18 inches) in length, the dorsal fin has become a fully-formed two-millimeter sucking disc. It still has the components found in the dorsal fin—the tiny fin spines, spine bases and supporting bones—but the spine bases have greatly expanded.

The study confirms that the specialized sucking disc is formed by a massive expansion of the dorsal fin through small changes while the fish is developing. This completely new structure is homologous to other fish with dorsal fins and is not an evolutionary offshoot.

Fins turning into suckers? It sounds like a super-power! Well done, remoras.

Image: Dave Johnson, Smithsonian Institution

Studies of bears and sea lions have enabled us to understand how these mammals reserve energy in the form of fat and blubber, sustaining them through winter or allowing them to travel great distances. And they aren’t alone in facing such physical challenges. Great white sharks also need a way to store energy during their long migrations, but until recently, their specific mechanism was unknown. (Maybe no one wanted to get too close to them…)

Great white sharks migrate between foraging and reproductive areas, traveling over 2,500 miles annually. While they are not known to be picky eaters, there is little food available far out in the Pacific Ocean.

Researchers at Stanford University and the Monterey Bay Aquarium studied how great whites could accomplish such a journey while fasting. But again, because great whites are, shall we say, just a wee bit dangerous, scientists needed to find ways to study the sharks’ lives without risking their own.

“The most difficult thing about this research was finding a way to bring all of the different sources of data together into a coherent and robust story,” said Gen Del Raye, a Stanford undergraduate who initiated the project. He knew that if they succeeded, they might shed light on storage strategies for other ocean mammals.

First the team studied a (well-fed) great white shark living at the Monterey Bay Aquarium. Over time the shark gained mass (but still maintained its flattering, streamline figure) and simultaneously increased in buoyancy.

Next the researchers pulled data from shark archival tags. Shark location information is time-stamped, enabling researchers to focus on one specific behavior, “drift-diving.” Huge marine animals sometimes act like hang gliders—they relax their fins while currents and momentum carry them forward. Drift-diving data provided the final clue to the research team: they established that migrating sharks lost buoyancy over time.

By measuring the rate at which sharks sink during drift dives, the researchers were able to estimate the amount of oil in the animals’ livers, which accounts for up to a quarter of their body weight. Sharks store oil before migration (making them float) then gradually use that energy throughout their journey (making them sink).

“Sharks face an interesting dilemma,” said Sal Jorgensen, a research scientist at the Monterey Bay Aquarium. “They carry a huge store of energy in the form of oil in their massive livers, but they also depend on that volume of oil for buoyancy. So, if they draw on those reserves, they become heavier and heavier.”

The new research paper might not only be used to help solve mysteries about other marine animals, but can also be used to assist conservation efforts around coastal feeding grounds.

“We have a glimpse now of how white sharks come in from nutrient-poor areas offshore, feed where elephant seal populations are expanding—much like going to an Outback Steakhouse—and store the energy in their livers so they can move offshore again,” said researcher Barbara Block, a professor of marine sciences and a senior fellow at the Stanford Woods Institute for the Environment. “It helps us understand how important their near-shore habitats are as fueling stations for their entire life history.”

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Image: Pterantula (Terry Goss)/Wikipedia

The court’s denial doesn’t mean the injunction will stay out of the courts completely, but it’s a great first step to strengthening the ban that prevents shark fins to be sold and served in restaurants in California.

AB 376 was introduced at the Academy nearly two years ago and passed both houses with support from the Asian-American community, WildAid, Shark Stewards and the Monterey Bay Aquarium. Governor Jerry Brown signed it into law in the fall of 2011.

The injunction was filed last summer by Bay Area organizations concerned with discrimination against Chinese-Americans, loss of income, and lack of proof that consuming shark fins actually endangers all species of sharks.

In Judge Hamilton’s decision, she addressed all of their concerns as she denied their claims. From the court order:

Plaintiffs’ own evidence shows that only a small percentage of Chinese-Americans eat shark fin soup regularly, and that approximately half of Chinese-Americans actually support the Shark Fin Law…

As for plaintiffs’ claim that the Law does nothing to protect sharks, the evidence provided by the defendant-intervenors and by amici provides strong support for defendants’ contention that the Law is intended to protect and conserve sharks and the marine ecosystems dependent on them by means of regulating local market conditions, which laws targeting the actual practice of shark finning in domestic waters alone do not address.

The “amici” Judge Hamilton refers to is the amicus curiae, in this case a brief written by McCosker, providing scientific evidence to the importance of all sharks and the harm that comes to them from shark finning. From that document:

Shark populations throughout the world’s oceans have dramatically decreased in recent years. One study estimates a decrease of 90% or more in shark populations, from their historical abundance… The rate of population decline for sharks has become more rapid during the last decade, due to the increasing value of shark fins.

In fact, the Pew Charitable Trust estimates that up to 73 million sharks per year are killed, primarily for their fins.

Beyond losing the sharks, McCosker detailed their importance to the larger ocean ecosystem in the brief:

As apex predators, sharks play an important ecological role. In particular, shark predation keeps populations of prey species in check, maintaining balance in marine ecosystems.

Before the ban was implemented, California was the second largest importer of shark fins, behind China. Banning shark fins worldwide still has a long way to go—last week new images surfaced of thousands of fins drying on Hong Kong rooftops and the Huffington Post ran a passionate argument to ban shark fin products in New York. But as McCosker says, it’s an important step in the right direction.

Image: Steve Corey/Flickr

On a recent autumn morning, Dave Ebert (pictured, left), an Academy research associate based in Moss Landing, California, backed his truck into the Academy’s loading dock. Working with graduate student Paul Clerkin (pictured, right), they unloaded several heavy tanks filled with the larger deep-sea shark specimens that Clerkin had collected during an expedition to the southern Indian Ocean. As they transferred the new specimens into the Academy’s ichthyology collection, final confirmation that ultimately would add eight new shark species from a little-known area of the world drew closer.

It took Ebert, who also serves as director of the Pacific Shark Research Center at the Moss Landing Marine Laboratories, two years to organize the expedition that sent the 27-year-old graduate student aboard a New Zealand-flagged fishing vessel, the Will Watch, in late February 2012. During the voyage that set sail from the island of Mauritius some 560 miles east of Madagascar, Clerkin collected nearly 400 specimens, including 25 to 30 representatives of known, but rarely seen, chondrichthyan species (cartilaginous fish such as sharks, rays, and chimaeras). Those sharks were found at depths from 800 to 1600 meters [2,600 to over 5,000 feet] deep and ranged in length from one to five feet.

“It’s a cliché to say that three-quarters of the Earth is covered with water,” says Ebert, who has researched chondrichthyans throughout the world’s oceans for more than twenty-five years. “But the truth is, the southern Indian Ocean is very remote and relatively little known. It has never been properly explored.”

Ebert’s interest was piqued in 2010 when a colleague at the United Nation’s Food and Agricultural Organization, focusing on the biodiversity in the southern Indian Ocean, requested his help to identify photos of some unusual chondrichthyans.

“Commercial fishermen were catching unusual sharks and wondered what they were,” he says. “Visually, their differences were obvious,” says the author of more than 300 publications and 12 books on chondrichthyans. “Clearly the region deserved further study.”

The next step, Ebert says, came when an executive from the Southern Indian Ocean Deepsea Fishers Association (SIODFA) contacted him several months later to gauge his interest in collaborating with SIODFA and the Republic of Mauritius’ Department of Fisheries. “It was a great idea,” he says, “but I needed to find a graduate student with considerable ocean-going experience who would not mind being at sea for two to three months.” In other words, a role that Ebert once fulfilled as a graduate student under the mentorship of the Academy’s senior scientist, John McCosker.

As Ebert pondered logistics, he turned his attention to financing the venture. A colleague had received funding from the National Science Foundation to work on phase two of the Chondrichthyan Tree of Life, an effort to catalogue and map the geographical diversity of sharks and rays. Ebert proposed the expedition would be a good fit and his colleague agreed the project would likely yield valuable data, and possibly new species.

There still remained the need for a qualified graduate student. Enter Paul Clerkin, a Cornell University graduate, who applied to work with Ebert at Moss Landing Marine Laboratories for his M.S. degree. “I have nine graduate students working on numerous projects,” Ebert says. “I picked Paul for his unique experience as a NOAA storm tracker and National Marine Fisheries Service certified observer in the Bering Sea.”

“I launched Paul on a crash course in identifying deep-sea chondrichthyans,” Ebert laughs. “Since I expected him to see new or unusual species, I wanted him to identify his species to the genus level if possible.”

Clerkin recalls the demanding protocol he followed to document the fish. “The number of sharks they caught as bycatch changed daily,” he says. “Sometimes I sampled five sharks all day, other times there were hundreds. I tried to document every shark that came onboard. However, there were hectic days when I only had time to take gender and length from the common sharks so I could perform detailed measurements on the rare ones.”

Ebert explains that adding the specimens to the Academy’s collection will enable international experts to review their work, a step as important in the discovery of new species as publishing one’s findings. Scientists have validated the discovery of approximately 150 new species of fish per year.

The Academy’s ichthyology collection and Catalog of Fishes database is renowned in scientific circles. According to Dave Catania, collections manager, the Academy holds 230,000 specimens representing 12,000 species of marine and freshwater fish. Of those, the Academy holds about 2000 scientifically significant, name-bearing type specimens.

“It’s best to think of our collection as a lending library,” Catania says. “Throughout the year, researchers arrive to study these specimens in our wet labs. Others need us to ship these specimens to laboratories around the world.”

Ebert adds, “We know that some of the specimens that Paul found are extremely rare. There’s a handful that we’re dead-on certain are like nothing we’ve ever seen.”

The transfer complete, Ebert takes off his baseball hat and grins broadly. “The Academy has been right there on the forefront of leading expeditions and naming new species. It’s a great time to get into the field and see what’s out there.”

Clerkin nods in agreement. For now, however, they climb back in the truck, eager to return to Moss Landing by nightfall.

Barbara Tannenbaum is a science writer working with the Academy’s Digital Engagement Studio. Her work has appeared in the New York Times, San Francisco Magazine and many other publications.

Villy Christensen of the University of British Columbia (UBC) said, “Yes, there will be fish left, but it will be a very different ocean from the ones your parents and grandparents knew and even different from now.”

The biggest difference? Large, predatory fish will be gone.

In fact, over the last one hundred years, the population of these large, top-of-the-food-web fish has declined by two-thirds, half of that decline occurring only in the last 40 years. And that population continues to decline.

There will be many small fish left, but not necessarily the ones we eat.

He and his colleague, Reg Watson, also from UBC, are working with scientists, governments and NGOs to build a global database of fishing efforts to truly understand what’s going on in the world’s oceans.

Seventy-six million tons of fish are consumed each year, and Watson found that we are fishing harder for the same or less result. It’s possible that we’ve hit “peak fish,” according to Watson. Jacqueline Alder of the UN Environment Program in Kenya is working with the UBC group, looking at their models in terms of marine biodiversity and sustainability. She urged that we must reduce fishing efforts immediately to allow fish stocks to rebuild.

In addition, there was much discussion around the non-sustainability of using fish for feedstock in aquaculture and agriculture– fish we are not directly eating. The science and technology have to get better to use plant-based feedstock for fish farms.

Christensen stressed this is a large view of what’s going on in the entire ocean ecosystem, not just one area or species.

For more focused, local information, read our recent article on banning shark finning, and the San Francisco Chronicle had a devastating article last week stating that some of the fish in the Delta may be too far gone to save from extinction.

Image: Mila Zinkova/Wikimedia