Modern seals, walruses, and sea lions are all descendants of animals that once lived on land but eventually swapped their terrestrial lifestyle for a life in the ocean. Until now, the morphological evidence for this transition from land to water has been weak, but researchers from Canada and the United States have now found a remarkably well preserved skeleton of a newly discovered carnivorous animal: Puijila darwini.

Skeletal illustration of Puijila darwini.
Credit: Mark A. Klingler/Carnegie Museum of Natural History

Seals, walruses and sea lions all have flippers; a type of limb perfectly adapted for swimming and moving around in water. But how could a land living animal develop flippers? The adaptation evolved gradually over a long period of time, as some land living animals adapted semi-aquatic habits. New research now suggests that the genus Puijila is the “missing” evolutionary link between our modern seals, walruses and sea lions and their terrestrial ancestors.

Puijila darwini is described as having fore-limbs comparatively proportionate to modern carnivorous land animals rather than to pinnepeds*, a long tail, and webbed feet.

“The remarkably preserved skeleton of Puijila had heavy limbs, indicative of well developed muscles, and flattened phalanges which suggests that the feet were webbed, but not flippers. This animal was likely adept at both swimming and walking on land. For swimming it paddled with both front and hind limbs. Puijila is the evolutionary evidence we have been lacking for so long,” says Mary Dawson, curator emeritus of Carnegie Museum of Natural History.

The Puijila darwini skeleton was found in Nunavut, Canada in the remains of what was once a crater lake on coastal Devon Island. The first pieces of the skeleton were found in 2007, but the important basicranium wasn’t found until researchers paid a new visit to the site in 2008. Without a basicranium it is much more difficult to determine taxonomic relationships.

Based on Paleobotanic fossils, Devon Island had a cool, coastal temperate climate during the Miocene when Puijila darwini roamed the seashore. The conditions were quite similar to modern-day New Jersey and the lakes would freeze during the winter, something which probably prompted Puijila darwini to move over land from the lake to the sea in search of food.

“The find suggests that pinnipeds went through a freshwater phase in their evolution. It also provides us with a glimpse of what pinnipeds looked like before they had flippers,” says Natalia Rybczynski, leader of the field expedition.

The idea that semi-aquatic mammals may have undergone a transition from freshwater to saltwater is not new. In the On the Origin of Species by the Means of Natural Selection, Charles Darwin writes “A strictly terrestrial animal, by occasionally hunting for food in shallow water, then in streams or lakes, might at last be converted in an animal so thoroughly aquatic as to brace the open ocean.”

The oldest well-preserved pinniped animal belongs to the genus Enaliarctos and was a sea living creature with flippers. This species has been found on North Americas northern Pacific shores which have lead researchers to believe that the evolution of pinniped animals may have taken place mainly around the Arctic. This new finding of Puijila darwini strengthens that notion.

You can find more information about Puijila darwini and the origin of pinnipeds in the April 23 issue of the journal Nature.

http://www.nature.com

http://www.nature.com/nature/index.html

* The pinnipeds are a widely distributed and diverse group of semi-aquatic marine mammals. It contains the families Odobenidae (walruses), Otariidae (eared seals, including sea lions and fur seals), and Phocidae (earless seals). The name is derived from the Latin words pinna, which means wing or fin, and ped, which means foot. The pinnipeds are therefore also known as fin-footed mammals.

The remains of a 15 meter[1] long sea living predator has been found in Svalbard, an archipelago located about midway between mainland Norway and the North Pole. The animal, a species of pliosaur dubbed Predator X by the group of scientists who discovered it, lived in the ocean 147 million years ago during the Jurassic period.

Predator X hunting (Photo: Atlantic Productions)

The skull of Predator X is twice as big as the skull of a Tyrannosaurus Rex and researchers believe the jaws of this hunter could exert a pressure of 15 tonnes[2]. The weight of the live animal is estimated to be around 45 tonnes[3].

“It is the largest sea dwelling animal ever found and as far as we know it is an entirely new species”, says palaeontologist Espen Madsen Knutsen[4] from the Olso University in Norway to Swedish newspaper Dagens Nyheter.

Knutsen is a part of the research team who dug out the skull and backbone of the creature during a two week long research expedition to Svalbard in June 2008. The remains were first discovered by Professor Jörn Hurum[5] from the Natural History Museum at Oslo University in 2007. Hurum noticed a piece of bone sticking up from the permafrost, but since it was the last day of the 2007 expedition the group was forced to leave the bone behind without any further investigation after having jotted down its GPS position.

Parts of the head and backbone was dug out during the abovementioned June 2008 expedition and together with an earlier find of a smaller specimen of the same species located just a few kilometres away, scientists have now managed to map together a good picture of what the live animal once looked like.

“We haven’t unearthed a high number of parts yet, but the parts that we do have are important ones and this has made it possible for us to create an image of what Predator X once looked like”, says Knutsen.

The digg site (Photo: Atlantic Productions)

In the excavated area, palaeontologist have found roughly 20,000 bone fragments – the remains of at least 40 different sea dwelling Jurassic animals. Once you’ve started digging in this region, it is fairly easy to spot the bones since their pale colour contrasts sharply against the black earth of the Svalbard tundra. The main difficulty is instead the short dig period and the fact that much time is spent restoring the excavated area after each dig.

“Each time we leave a dig site we have to restore the area. There can be no traces of our activities. This forces us to use half of our time digging up the same spot all over again when we return”, Kutsen explains.

Svalbard lies far north of the Arctic Circle and the average summer temperature is no more than 5°C (41°F), while the average winter temperature is a freezing −12 °C (10 °F). In Longyearbyen, the largest Svalbard settlement, the polar night lasts from October 26 to February 15. From November 12 to the end of January there is civil polar night, a continuous period without any twilight bright enough to permit outdoor activities without artificial light.

The team plans to return to Svalbard this summer to carry out more digging. They hope to find another specimen in order to make the skeleton more complete, and they also wish to unearth the remains of other animals that inhabited Svalbard at the same time as Predator X.

If you wish to learn more, you can look forward to the documentary shot by Atlantic Productions during the Svalbard excavations. The name of the documentary will be Predator X and the animal is actually named after the film, not the other way around. The film will be screened on History in the USA in May, Britain, Norway and across Europe later this year and distributed by BBC Worldwide.

Pliosaur crushing down on Plesiosaur with 33,000lb bite force (Ill.: Atlantic Productions)

All the scientific results will be published in a full scientific paper later this year.

You can find more Predator X information (in English) at the Natural History Museum, University of Oslo: http://www.nhm.uio.no/pliosaurus/english/

Chinese ichthyologists Yang, Chen and Yang have described three new species of snow trout in a paper[1] published in the journal Zootaxa[2]. All three species have been described from material previously identified as one single species, Schizothorax griseus. True trouts belong to the Salmoninae subfamily in the Salmonidae family, but snow trouts are members of the family Cyprinidae.

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cypriniformes
Family: Cyprinidae
Genus: Schizothorax

New species: Schizothorax beipanensis

Schizothorax heterophysallidos

Schizothorax nudiventris

Schizothorax beipanensis

Schizothorax beipanensis is found in southern China where it inhabits the Beipan River drainage, a part of the Pearl River drainage. It has been encountered in both slow-flowing deep pools and fast-flowing rivers with clear water and over a wide range of different bottom substrate, from mud and sand to rocks, boulders and pebbles.

Schizothorax beipanensis differs from its close relatives by having well-developed upper and lower lips (the lower lip is actually tri-lobed), no horny sheath on the lower jaw, and a continuous postlabial groove with a minute median lobe.

Schizothorax heterophysallidos

Just like Schizothorax beipanensis, the snow trout Schizothorax heterophysallidos is found in the Pearl River drainage in southern China, but it lives in the river drainage of Nanpan, not Beipan. Schizothorax heterophysallidos lives in small streams where the bottom consists of sand and pebbles.

The name heterophysallidos is derived from the unusual swim bladder of this fish; physallis is the Greek word for bladder and heteros means different. In addition to the swim bladder (the posterior chamber of the air bladder is three to six times longer than the anterior chamber), Schizothorax heterophysallidos can be recognized on its well-developed and trilobed lower lip, thin upper lip, and blunt snout. It has a continuous postlabial groove with a minute median lobe and the last unbranched dorsal-fin ray has a strong lower part. In mature specimens, the abdomen lacks scales.

Schizothorax nudiventris

Schizothorax nudiventris also lives in southern China, but in the upper parts of the Mekong River drainage. The Mekong basin is one of the richest areas of biodiversity in the world. More than 1200 species of fish have been identified here and the number is believed to increase as the area becomes more thoroughly explored by science.

Schizothorax nudiventris has a well-developed and trilobed lower lip, thin upper lip, blunt snout, and continuous postlabial groove. The body is decorated with irregular black spots on the sides, and the last one-quarter of the last unbranched dorsal-fin ray is soft. In mature specimens, the abdomen has no scales, and it is this feature that has given the fish its name nudiventris. Nudus is the Latin word for naked, while venter means abdomen.

The hydrothermal vents that line the mid-ocean ridges are a major source of iron for the creatures living in the sea. Humans are not the only ones who suffer when iron becomes scarce; creatures such as phytoplankton are known to grow listless in waters low in iron, even if they are drifting around in an environment rich in many other types of nutrients.

Earlier, scientists assumed that the iron exuded from hydrothermal vents immediately formed mineralized particles as soon as it came in contact with the salty water – a form of iron that is hard to utilize for living creatures.

New research has however unveiled that some of the iron spewed out from these vents actually remain in a form that is easy to absorb for oceanic beings. According to researcher Brandy Toner, a surprising interaction between iron and carbon in hydrothermal vents serves to stop the corrosion.

“Iron doesn’t behave as we had expected in hydrothermal plumes. Part of the iron from the hydrothermal fluid sticks to particulate organic matter and seems to be protected from oxidation processes,” Toner explains.

The research was carried out on hydrothermal vent particles collected by the team from the Tica vent in the Eastern Pacific Rise. With the help of the Advanced Light Source synchrotron at the Lawrence Berkeley National Laboratory, Toner was able to analyze the particles using focused X-ray beams.

Iron is a key player in this newly discovered process in the ocean, but the exact mechanisms remains unknown.

“So the question becomes, what are those organic compounds? Are they organic compounds like in oils and tars or is it actually the stuff of life?”, says Chris German, co-author of the paper. “Brandy’s work doesn’t mean that these [carbon-iron] complexes are definitely alive. But, this is a possible smoking gun. This paper opens up a whole new line of research and asks a new set of questions that people didn’t know they should be worrying about until now. A bit of work on a tiny nanometer scale can force you to ask questions of global significance.

Perhaps hydrothermal venting, a process traditionally believed to be a completely inorganic process, actually is a part of the organic carbon cycle on our planet.

The paper “Preservation of iron (II) by carbon-rich matrices in a hydrothermal plume” by Brandy Toner and her colleagues[1] has been published in Nature Geoscience[2].

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Aquarium Toplist function added

New research has revealed that the tapetail, bignose and whalefish are in fact all the same fish.

For decades, three different names have been used for three very different looking underwater creatures: the Tapetail, the Bignose and the Whalefish. A team of seven scientists*, including Smithsonian curator Dr Dave Johnson, has now discovered that these three fishes are in fact part of the same family.

After studying the body structures of the tapetails (Mirapinnidae), bignose fish (Megalomycteridae) and whalefish (Cetomimidae) and taking advantage of modern DNA-analysis, the team realized that the three are actually the larvae, male and female, respectively, of a single fish family – Cetomimidae (also known as Flabby whalefish).

“This is an incredibly significant and exciting finding,” says Johnson. “For decades scientists have wondered why all tapetails were sexually immature, all bignose fishes were males and all whalefishes were females and had no known larval stages. The answer to part of that question was right under our noses all along—the specimens of tapetails and bignose fishes that were used to describe their original families included transitional forms—we just needed to study them more carefully.”

If you wish to find out more, the article “Deep-sea mystery solved: astonishing larval transformations and extreme sexual dimorphism unite three fish families” has been published in the journal Biology Letters by the Royal Society, London.

http://publishing.royalsociety.org/

http://journals.royalsociety.org/content/g06648352k5m1562/

* The seven scientists behind the discovery are:

G.David Johnson, Division of Fishes, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA

John R. Paxton, Ichthyology, Australian Museum, Sydney, New South Wales 2010, Australia

Tracey T. Sutton, Virginia Institute of Marine Science, Gloucester Point, VA 23062, USA

Takashi P. Satoh, Marine Bioscience, Ocean Research Institute, University of Tokyo, Nakano-ku, Tokyo 164-8639, Japan

Tetsuya Sado, Zoology, Natural History Museum and Institute, Chuo-ku, Chiba 266-8682, Japan

Mutsumi Nishida, Marine Bioscience, Ocean Research Institute, University of Tokyo, Nakano-ku, Tokyo 164-8639, Japan

Masaki Miya, Zoology, Natural History Museum and Institute, Chuo-ku, Chiba 266-8682, Japan

A group of scientists from the Catalyst One expedition has discovered three previously unknown coral reefs 35 miles of the coast of Florida. The coral reefs consist mainly of Lophelia coral and are located at a depth of 450 metres (1475 feet).

Lophelia pertusa is a cold-water coral famous for its lack of zooxanthellae. The well known coral reefs found in warm, shallow waters – such as the Great Barrier Reef – consist of reef building corals that utilize energy from the sun by forming symbiotic relationship with photosynthesising algae. Lophelia pertusa on the other hand lives at great depths where there isn’t enough sunlight to sustain photosynthesising creatures, and survives by feeding on plankton.

The deep-sea reef habitat formed by Lophelia pertusa is important for a long row of deep water species, such as lanternfish, hatchetfish, conger eels and various molluscs, amphipods, and brittle stars. The reefs that we see today are extremely old, since Lophelia reefs typically grow no more than 1 mm per year. Unfortunately, these deep reefs are today being harmed by trawling and oil extraction.

The Catalyst One expedition will submit its newly acquired information to the South Atlantic Fisheries Management Council to provide further data for the proposed Deep Coral Habitat Area of Particular Concern (HAPC).

The Catalyst One expedition is a collaboration between the Waitt Institute for Discovery, the Harbor Branch Oceanographic Institute at Florida Atlantic University, and Woods Hole Oceanographic Institute. It combines the scientific expertise of Harbor Branch’s senior research professor, John Reed, with Woods Hole’s high-tech operations skills and Waitt Institute’s modern autonomous underwater vehicles (AUVs).

In order to reach these great depths and efficiently explore substantial areas, the expedition used REMUS 6000 AUV vehicles capable of carrying two kinds of sonar and a camera. With this type of equipment, each mission can last for up to 18 hours and provides the researchers with mosaic pictures of the bottom, pictures that can then be pieced together to form a detailed, high-definition map.

“Rarely do scientific expeditions produce solid results this quickly,” says Dr Shirley Pomponi, executive director of Harbor Branch. “This is a big win for the resource managers tasked with protecting these reefs and proof that cutting edge technology combined with the seamless teamwork of the three organisations involved in Catalyst One can accelerate the pace of discovery.”

You can find more information about the Catalyst program at the Waitt Institute for Discovery.

http://waittinstitute.org/wid/catalyst/

http://waittinstitute.org/wid/news/catalyst1.html

A UK-Japan team equipped with remote-operated landers has now managed to film a shoal of Pseudoliparis amblystomopsis fish at a depth of 7.7 km (4.8 mi) in the Japan Trench, where the oceanic Pacific plate subducts beneath the continental Eurasian plate.

The deepest record for any fish – over 8 km / 5 mi – is held by the species Abyssobrotula galatheae, but this fish was never filmed or observed while it was alive; it was dredged from the bottom of the Puerto Rico Trench and already dead when it reached the surface.

The Pseudoliparis amblystomopsis film shows the fish darting around in the dark, scooping up shrimps. The shoal consists of no less than 17 specimens, with the largest ones being around 30 cm (12 in) in length.

“It was an honour to see these fish“, says Dr Alan Jamieson, Research Fellow at the University of Aberdeen, Scotland. “No-one has ever seen fish alive at these depths before – you just never know what you are going to see when you get down there.

The filming took place as a part of the Hadeep project; a collaboration between the Oceanlab at the University of Aberdeen and the Ocean Research Institute at the University of Tokyo. The aim of the project, which is funded by the Nippon Foundation and the Natural Environment Research Council, is to find out more about life in the very deepest parts of the world’s oceans.

Just like the unfortunate Abyssobrotula galatheae, deep sea fishes tend to be in a sad state when researchers examine them at the surface and this is one of the reasons why a film is such great news for anyone interested in learning more about what’s going on at these vast depts.

According to Professor Monty Priede, also from the University of Aberdeen, the team was surprised by the fish’s behaviour. “We certainly thought, deep down, fish would be relatively inactive, saving energy as much as possible, and so on,” says Priede. “But when you see the video, the fish are rushing around, feeding accurately, snapping at prey coming past.“

Oceanographers normally divide the deep sea into three different depth zones:

• The Bathyal, which is located between 1,000 and 3,000 m (3,000 and 10,000 ft)
• The Abyss, which is located between 3,000 and 6,000 m (10,000 and 20,000 ft)
• The Hadal, which is located between 6,000 and 11,000 m (20,000 and 36,000 ft)

The Hadeep project has been looking at the creatures inhabiting the Hadal zone, which consists of comparatively narrow trenches in the wide abyss. In this environment there is no light and the pressure is immense. The food supply is also very limited, since photosynthesising organisms can not survive and most other creatures stay away as well. The animals living in the Hadal zone must therefore rely on food sinking down to them from more fruitful waters above.

In order to cope with pressure, Hadal dwellers display numerous physiological modifications, primarily at the molecular level. They have also developed various ways of dealing with the constant night and Pseudoliparis amblystomopsis is for instance equipped with vibration receptors on its snout which comes in handy when the fish navigates through the darkness and searches for food.

Dr Alan Jamieson now hopes that the Japan-UK team will find more fish during their next expedition down into the Haldal zone, which is planned to take place in March 2009 and aims to venture as far down as 9,000 m (30,000 ft).”Nobody has really been able to look at these depths before – I think we will see some fish living much deeper,” says Jamieson, whose deep-sea blog from the expedition can be found at Planet Earth Online.

You can also read more about this story over at deep sea news, a great blog if you want to keep up to date on deep sea discoveries.

In a new study on Tanganyika cichlids, three scientists[1] [2] [3] from Uppsala University in Sweden have shown that intricate rearing behaviour varies with brain size in females. The only previously published study showing similar patterns concerned predatory animals.

Tropheus moori – one of the species used in the study. – Picture www.jjphoto.dk

How the vertebrate brain has developed throughout the course of evolution is still not clear, and we are still not certain if brain functions in a specific species develop to match a demanding environment. One way of learning more about this is to compare brain size and structure in closely related species living under dissimilar circumstances.

“It is important to look at differences between males and females since females often distinguish themselves from males, both in behaviour and appearance”, says Niclas Kolm, lead-author of the study.

The study looked for correlations between brain size and ecological factors in a large number of specimens from 39 different species of Tanganyika cichlid. Lake Tanganyika is especially suitable for this type of study since it is inhabited by cichlid groups exhibiting significant dissimilarities in both brain structure and ecology, and whose ancestry is well known. Tanganyika cichlids varies dramatically from species to species when it comes to factors such as body size, diet, habitat, parental care, partner selection, dissimilarities between the sexes, mating behaviour, and brain structure.

The result of the study showed a correlation between brain size and the two factors diet and parental care behaviour. Species where only the female fish cares for egg and fry turned out to have bigger brains than species where both parents engage in parental care. The brain was however only larger in females; there was no difference in brain size between males of the two groups.

The largest brains of all were found in algae-eating cichlids. These fishes live in environments characterized by a high level of social interaction. “This indicates that social environment have played a role in brain development”, says Kolm.

The study was published in the web version of “Proceedings of the Royal Society of London Series B” on September 17. You can find it here (http://journals.royalsociety.org/content/j114062824820l76/).

According to a new study from Uppsala University, the origin of fingers and toes can be traced back to a type of fish that inhabited the ocean 380 million years ago. This new finding has overturned the prevailing theory on how and when digits appeared, since it has long been assumed that the very first creatures to develop primitive fingers were the early tetrapods, air-breathing amphibians that evolved from lobed-finned fish during the Devonian period and crawled up onto land about 365 million years ago.

Lead author Catherine Boisvert[1] and co-author Per Ahlberg[2], both of Uppsala University in Sweden, used a hospital CT scanner to investigate a fish fossil still embedded in clay. “We could see the internal skeleton very clearly, and were able to model it without ever physically touching the specimen,” says Ahlberg. The scan revealed four finger-like stubby bones at the end of the fin skeleton. The bones were quite short and without joints, but it was still very clear that they were primitive fingers. “This was the key piece of the puzzle that confirms that rudimentary fingers were already present in the ancestors of tetrapods,” Catherine Boisvert explains.

The scanned fossil was that of a meter-long Panderichthys, a shallow-water fish from the Devonian period. Panderichthys is an “intermediary” species famous for exhibiting transitional features between lobe-finned fishes and early tetrapods, while still clearly being a fish and not a tetrapod. The specimen used was not a new finding; it had just never been examined with a CT scan before.

So, why have researchers for so long assumed that digits were something that evolved in tetrapods without being present in their fishy ancestors? The main reason is the Zebra fish (Danio rerio), a commonly used model organism when vertebrate development and gene function is studied. If you examine a Zebra fish, you will find that genes necessary for finger development aren’t present in this animal. Researchers therefore assumed that fingers first appeared in tetrapods and not in fish.

It should be noted that similar rudimentary fingers were found two years ago in a Tiktaalik, an extinct lobe-finned fish that lived during the same period as Panderichthys. Tiktaalik is however more similar to tetrapods than Panderichthys.

The Panderichthys study was published in Nature on September 21.

As you probably know already, many sea living creatures are capable of emitting their own fluorescent light. Turning yourself into a living light bulb comes in handy when you live at depths where no sunlight or only very little sun light is capable of reaching you, and the glow can for instance be used for communication, as camouflage, or to lure in prey.

Up until now, most fish experts have assumed that marine fish living below a depth of 10 metres (30 feet) could not be red since the type of sunlight necessary for the colour red to be visible to the eye isn’t capable of travelling so far down into the ocean, and why would an animal develop a red pigmentation that nobody could see in its natural habitat?

New light has now been shed on the situation and – according to a study published on September 15 by researchers at the University of Tubingen in Germany – fish living at these depths have managed to circumvent the problem of light scarcity by emitting their own red fluorescent light instead of relying on sun beams to display their colours. According to the study, a lot of marine species are capable of emitting a fluorescent red light which can be seen even at depths below 10 meters.

“The general consensus, which dominated fish literature for 20 or 30 years, was that fish don’t see red very well or at all,” says Nico Michiels, one of the researchers behind the study. “We have been blinded, literally, by the blue-green light that is available on reefs in the daytime.”

The scuba diving research team made their discovery when looking through a filter that blocked out the brighter green and blue light waves. While using the filter – which leaves only red light waves – the scientists realised that their dive spot was inhabited by a long row if different marine creatures capable of emitting their own red light. In addition to fish, they saw fluorescent red coral, algae and other small organisms.

Further investigation revealed that the red glowing organisms use guanine crystals to produce their light. Guanine is one of the five main nucleobases found in DNA and RNA and guanine crystals are commonly used by the cosmetics industry to give products such as shampoo, eye shadows and nail polish a shimmering lustre. As early as 1656, a Parisian rosary maker named François Jaquin extracted crystalline guanine forming G-quadruplexes from fish scales – so called pearl essence. Guanine crystals are rhombic platelets composed of multiple transparent layers and the pearly lustre appears when light is partially reflected and transmitted from layer to layer.

The red fluorescent light emitted by the organisms studied by Michiels and his colleagues is only visible at a close distance, at least to us humans. More research is now needed to investigate why so many sea dwellers have developed this capacity and how the red colour benefits them in their daily life.