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Grunters, 'Hardyhead' Among 20 Newly Found Fish

The finds boost Australia’s total number of known freshwater fish species by nearly 10 percent.

Twenty new species of freshwater fish have been discovered in a remote part of Australia, scientists at the University of Melbourne have just announced.

The finds boost Australia's total number of known freshwater fish species by nearly 10 percent, and highlight a region called the Kimberley as being the nation's most biodiverse area for these kinds of fish. The Kimberley is Western Australia's sparsely settled northern region.

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"The freshwater ecosystems of the Kimberley are among the poorest known and least researched areas of Australia," associate professor Tim Dempster of the university's School of Biosciences said in a press release.

"Certainly, it is a treasure trove for freshwater fish - and the amazing thing is that we weren't even looking for it," he added.

The discoveries were made as Dempster and his team were in the Kimberley studying extinction risks for freshwater fish there. A helicopter was used to enter parts of the area. The scientists also did some snorkeling, which proved to be dangerous.

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Researcher James Shelley, for example, was attacked by a crocodile while snorkeling in the Glenelg river on the Kimberley plateau. The crocodile bit him right in the forehead, but could not get a full grip on Shelley, who survived to tell the tale and is fine now.

The new fish species fall within three categories:

Terapontidae (grunters) 16 new species Eleotridae (gudgeons) 3 new species Atherinidae (hardyheads) 1 new species Grunters really do grunt when threatened, sounding somewhat like a pig. Gudgeons are small, spiny-finned freshwater fish. Hardyheads are small too, and are not known for their heads, as their name would suggest, but instead for their silvery, iridescent bodies.

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One of the new grunters from the Prince Regent River will be named after popular Australian novelist Tim Winton. On a morning news show, he quipped that the "redneck" in him wonders what the fish tastes like, but he added that the namesake fish "is a great honor."

Explaining the name, Shelley said, "It's in recognition of (Winton's) contribution to Australia's cultural life, his love of fish which shines through in many of his novels, and his staunch advocacy for conservation in the Kimberley."

Most of the new fish are limited to very small habitats, so Winton and the scientists are already concerned about their welfare. Dempster and the University of Melbourne are in the process of creating a conservation fund that would aim to protect Australia's 220-plus freshwater fish and other marine life.

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Such conservation efforts are critical, particularly in light of the fact that 2016 has already seen at least eight extinctions. The Smithsonian Institution announced earlier this week that eight Panamanian species of frogs are now extinct in the wild due to disease-related declines.

Identifying extinctions, as well as new species, is an ongoing effort for researchers, who hope to prioritize saving not only particular animals, but also bio-rich areas such as the Kimberley and parts of Panama.

Researchers working in the Kimberley region of Australia.

It's a fish-eat-fish world, so many fish have evolved unusual body shapes to deter other fish from swallowing them, new research finds. The study, published in the journal Proceedings of the Royal Society B, points out that biting off more than one can chew is not an option for most aquatic predators. As a result, thousands of prey species have evolved bodies that are ultra wide, round, narrow, spiked or are otherwise designed not to be the perfect morsel. "Almost every fish that eats other fishes captures their prey with their mouths, and so the prey must fit into their mouth; this is also true for some fish-eating birds, such grebes and herons," lead author Samantha Price of the University of California at Davis' Department of Evolution and Ecology told Discovery News. "Not all predators are gape-limited, but over the history of fishes, it is likely that many of the predators would have been limited by the size of their mouth." This sea devil can be both predator and prey, as its human-like mouth, yet flat body shape, suggest. There are multiple reasons for "misshapen" bodies among fish, but avoiding fitting into a hunter's mouth turns out to be a critical one.

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Imagine trying to fit this into your mouth. The flying gurnard makes maximum use of body area without investing much energy in fleshy substance. The new study, which looked at over 25,000 living fish species, found that evolution of fish such as this was shaped by gape-limited predators, meaning marine hunters that can only open their mouths so far.

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In addition to body shape, many fish have evolved bumpy skin, fin spines and other features that deter a predator from simply sucking the fish into their mouth like a smooth piece of sushi. The researchers determined that fish with spines that extend vertically evolve toward "deeper" bodies. Deep in this case means having a more vertical yet narrow, rounded body, sort of like a pancake on its side. The slantbrow batfish is just the opposite. It is considered to be a wider-bodied fish, like a flat, albeit misshapen, pancake floating in the water. These wider-bodied fish often evolve spines that extend horizontally. Price said that the spines and body depth "work together to defend against predators." She continued that if the prey fish "becomes bigger, the predator will not be able to eat it, but increasing the overall size is energetically costly, so it is better just to increase a single dimension: either width or depth."

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On the predator side are fish like this giant grouper. Sharks often grab our attention because of their appearance and apex predator status, but groupers like this have been known to eat sharks from time to time using their huge mouths and relentless hunting tactics.

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The leafy sea dragon belongs to the marine fish family that also includes seahorses and pipefish. Its small fins not only increase its body surface area, but they are also difficult to view as they subtly undulate while the seadragon moves slowly through the water. Here, camouflage is another benefit of body shape. When in motion, this seadragon looks remarkably like a piece of floating seaweed.

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Garden eels, needlefish and spaghetti eels use another tactic to avoid being eaten. Like actual spaghetti, they are extremely thin and tend to slip out of a predator's mouth.

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"Fishes display an incredible diversity of body sizes, including lineages that are almost as wide or as deep as they are long," Price said. "Our findings suggest that predation has helped shape this diversity, although many other factors, such as habitat or diet, are also likely to be important drivers of fish body form evolution."

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This red lionfish looks to be posing for the camera, displaying its showy colors and fins. Predators would do well to notice and move away, as lionfish are venomous. Spines on such fish therefore are doubly dangerous. "The spines can damage the predator and species that have venom associated with the spines will cause even more problems," Price explained. "There are some rather grisly photos online of some injuries to fishermen and swimmers who have been on the wrong end of fish spines!"

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Moonfish are classic examples of fish that have evolved extremely deep body sizes that the researchers say deter gape-limited predators. The moonfish body is also sharp-edged and covered on the top and bottom with small spines that make handling them challenging. Brian Sidlauskas is an associate professor and curator of fishes at Oregon State University's Department of Fisheries and Wildlife. He told Discovery News that the new study provides "an elegant demonstration" of at least one "critical piece" of fish body form evolution.

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When deflated, puffer fish look like helpless, tiny prey. Once inflated, though, they become deadly mouthfuls for many would-be diners. Prosanta Chakrabarty of Louisiana State University agrees that spines not only work against predators via their sharpness and possible venom, but also because they help certain fish to become wider or deeper bodied. "That might sound intuitive, but it really isn't," he informed Discovery News. "Your bodies are constrained in how deep or wide they can get because these animals still need to try to avoid predators, get their own prey, move around the water column, and find mates." He continued, "The spines, which are not similarly constrained, allow these fishes to reach these depths and widths despite the constraints on the body. That is a microevolutionary solution to a macroevolutionary constraint."

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