Helicoprion: Mystery of ancient Spiral-Toothed Shark clarified

An ancient spiral-toothed fish has been reconstructed from fossil evidence by scientists.

US researchers used CT scans to build a computer model of what Helicoprion looked like and how it ate.

They were also able to resolve an ongoing puzzle over whether the unique saw-like spirals were located inside or outside the mouth.

The findings show the animals were more closely related to modern chimaeras, or ratfish, than sharks.

The study is published by researchers from Idaho State University in the Royal Society journal Biology Letters.

The university's Museum of Natural History has the largest public collection of fossilised Helicoprion in the world.

The fish lived 270 million years ago but because they were largely formed from cartilage, which does not preserve well, their fossil record comprises unusual spiral structures.

Referred to as "whorls", these features have been compared to spiralling saw blades and have puzzled the scientific community for over a century.

Early theories suggested that they were actually used for defence and were located on the fish's upper or lower jaws, or even the dorsal fin.

Dental records
To solve the mystery, Dr Leif Tapanila and colleagues investigated the most complete fossil in the collection.

The fossil, discovered in Idaho, has a whorl measuring 23cm with 117 individual teeth. Unlike other specimens, the fossil also includes impressions of the cartilage structures.

The team used a high-powered CT scan, which uses X-rays to create a detailed computer image, in order to fully analyse what was inside the rock.

"When we got the images back, we could easily see that we had the upper and lower jaw of the animals, as well as the spiral of teeth," said Dr Tapanila.

"For the first time we were able to very clearly image how that spiral of teeth relates to the jaw."

The scientists found that the spiral was connected to the fish's lower jaw, in the back of the mouth.

"Imagine that... instead of having a tongue, you have this large spiral of teeth," Dr Tapanila explained.

"Only maybe a dozen teeth are poking up out of your lower jaw so you can bite."

"The rest of those teeth are stored inside and are not being used, those are your baby teeth - the teeth you had when you were younger."

Dr Tapanila said this discovery supports the argument that unlike sharks, which constantly replace their teeth, Helicoprion retained its teeth permanently.

Using the computer images, the team could build a 3D model of the jaw, to reveal how the tooth spiral worked.

"As the mouth closes, the teeth spin backwards... so they slash through the meat that they are biting into," Dr Tapanila reported.

"The teeth themselves are very narrow: nice long, pointy, triangular teeth with serrations like a steak knife.

"As the jaw is closing and the teeth are spinning past whatever it's eating, it's making a very nice clean cut."

Of the 100 fossils of Helicoprion that have been discovered, very few show broken or worn teeth.



Ancient diet
Dr Tapanila said that this evidence, combined with the "rolling and slicing" mechanism, provided clues to what the ancient fish ate.

"If this animal were eating other animals that were very hard or [had] hard armour plating or dense shells, you would expect more damage to their teeth.

"This leads us to believe that our animal was probably eating soft, squishy things like calamari. It was probably eating squid or its relatives that were swimming in the ocean at the time."

The study also highlighted the family connections of the ancient fish, categorising it with chimaeras and ratfish rather than sharks.

"One of the main ways that fish are identified is based on how the upper jaw connects to the rest of the skull," said Dr Tapanila.

"Because we have the upper jaw we can look at the bumps and grooves on it and see how it would have connected.

"It was fixed in two positions and was fused essentially to the brain tip... a feature that's distinctive for chimaeras and ratfish."

Following the reconstruction the jaw of the fish, the team is using inferred characteristics to create a scale model of the 4m animal for an exhibition at the Idaho State University Museum of Natural History this summer.

Based on fossil evidence, scientists believe the fish could have measured up to 7.6m long.

Dolphin attacking Mackerel Image

British photographer Christopher Swann took these amazing shots of dolphins and sharks preying on mackerel of the coast of Azores. 

The frightened mackerel swarm into these giant glistening balls in order to protect themselves from the impending attack. 

In the end, the predators win out over the 30-foot wide ball of prey.

See more of his images of the Mackerel here.

Shark Finning: Venezuala Takes Steps toward survival

Credit: Federico Cabello

Some much-needed good news for sharks has come from Venezuela this week: The South American country announced it is banning shark finning in its waters and has established a new shark sanctuary.

The country became the last in the Americas to outlaw the practice of cutting off the fins of live sharks and tossing the animals back into the ocean to slowly die.

A Lemon Shark gives a diver a high-five

Eli Martinez was interacting with the lemon shark in the balmy waters off the coast of The Bahamas.

Eli, who works as the editor of Shark Diving magazine, said: "This particular shark I had encountered before. She is very laid-back so I knew if I held my hand out she would come over. At first she was swimming straight towards me, but I didn't expect her to turn at the last moment. She tapped my palm with her fin like we were high-five-ing."

The Dependent link between Fishermen, whales and sharks

A whale shark approaches a local fisherman to be hand-fed brine shrimp in shallow waters off Oslob, Philippines.

Local fisherman display their unusual hand-to-mouth relationship with giant 25ft long whale sharks.

Picture: Shawn Heinrichs / Barcroft Media

We would also like to say 'Hi' to Kay Engman, Art Associate for Science Journal for American Association for the Advancement of Science.

Europe Acts to Save Sharks from Finning and Fishing Nets

Europe acts to protect sharks (long version)
This video graphically illustrates the beauty of sharks and the danger which threaten their survival. The images are only copyright free for a duration of 5 years as from january 2009 until january 2014.

These images can only be used in context of this video news release. The images have been provided by Greenpeace and OceanFootage.

To read more about EUROPEAN Commission Protection measures click here

First Teeth Grew on the Outside of the Body

The tooth-like lip and cheek scales were found in specimens of ischnacanthid acanthodians similar to this one from the University of Alberta Laboratory for Vertebrate

• New research on Early Devonian fish suggests that the world's first teeth evolved outside of the mouth.
• Scales on the exterior of the prehistoric shark-resembling fish appear to have evolved into teeth.
• Teeth were retained among most vertebrates and were passed down to multiple species, including humans.

The fictional Cheshire cat's smile seemed to have a life of its own, outside of the cat's body, and now new research suggests the world's first teeth grew outside of the mouth before later moving into the oral cavity.

The study, published in the Journal of Vertebrate Paleontology, supports what is known as the "outside-in" hypothesis of tooth evolution. The first teeth and smile, however, did not belong to a cat, but likely were flashed by small and spiny shark-like fishes.

That initial smile would have looked rather sinister.

"The first smile would probably have been a prickly one, with many tiny teeth that looked like pointy cheek scales, and other small tooth-like scales wrapping around the lips onto the outside of the head," co-author Mark Wilson told Discovery News.

For the study, Wilson, a professor in the Department of Biological Sciences at the University of Alberta, and his colleagues studied animals called ischnacanthid acanthodians, an extinct group of fish that resembled sharks.

They lived during the Early Devonian period, which lasted from 416 to 397 million years ago.

The researchers determined that head scales from these fish were in transition, evolving from scales to teeth. The pointy structures were identified on the lips of the fish.

This discovery helps to negate the “inside out” theory of tooth evolution, which holds that the first teeth emerged from structures in the pharynx progressing into the mouth.

Project leader Stephanie Blais, a University of Alberta researcher, told Discovery News that "our findings support the idea that teeth evolved from modified pointed scales on the mouth margins (lips) as we see in Obtusacanthus," one of the prehistoric fish included in the study.

All of the analyzed fish specimens were excavated at the Man on the Hill site in the Mackenzie Mountains of Canada.

As to why teeth first evolved, Blais said they "would have conferred a major advantage in terms of food acquisition. Pointed scales near the margins of their mouths would have helped them grasp prey and hang on to it until they could swallow it whole."

Such prey consisted of "probably whatever they could swallow," co-author Lindsay MacKenzie of the University of Montana’s Department of Geosciences told Discovery News.

Based on fossilized stomach contents and other evidence, their primary prey probably consisted of arthropods, including crustaceans, as well as a variety of soft-bodied creatures and fish.

Blais said jaws, which must have evolved earlier, and the tooth-like formations "allowed fishes to change from a filter-feeding or mud-grubbing more passive lifestyle to one of active predation."

The world's first aggressive conflicts also may have arisen at this point, since the move from passive feeding to hunting led to what Blais termed "the very first evolutionary arms race" among vertebrates, with some becoming predators and others becoming prey.

Scottish Shark Conservation and Tagging

The Scottish Shark Tagging Programme (SSTP) is a branch of the Scottish Sea Angling Conservation Network  www.ssacn.org whose objectives are to :

• to tag and record data on many of the shark, skate and ray species found within Scottish coastal waters
• Increase public awareness highlighting the need for shark protection
• Encourage use of “codes of best practice”
• to highlight sea anglers conservation efforts
• show government agencies that sea anglers are a vital part of data gathering
• and that properly managed sea angling stocks can provide huge socio economic benefits
• to directly contribute to shark fisheries management

Joining the SSTP is free – just use the  ‘Contact Us’ page to send us an email.

Answers to some of the more frequently asked questions follow :

Why Save Sharks ?
Most sharks serve as top predators at the pinnacle of the marine food pyramid, and so play a critical role in ocean ecosystems. Directly or indirectly they regulate the natural balance of these ecosystems – at all levels – and so are an integral part of them.

The effects of removing sharks from ocean ecosystems, although complex and rather unpredictable, are likely to be ecologically and economically damaging.

Who can tag ?

The SSTP will be free to enter, subject to available funding, and available to all disciplines of sea angler, be they shore, small boat, club or charter anglers. Though the programme will aim to provide the greatest coverage through charter boats and clubs, as this will give the best concentrated use of the limited number of tags available each year. We will encourage all anglers to abide by the “codes of best practise” and may insist new taggers attend a short course at a local centre or spend time with an approved tagger.

What else will the SSTP be doing?
SSACN and the SSTP will work in partnership with government agencies like the Scottish Natural Heritage (SNH), Marine Directorate and Fisheries Research Scientists (FRS) and academic institutions such as Millport Marine laboratory and Glasgow University to help provide a focal point for shark research.

We are also seeking funding for satellite tags and for stock survey assessments.

Commercial fishermen are a huge source of knowledge and we will endeavour to liaise with fishers to ensure best practice on discarded fish and hopefully use their knowledge to ascertain bycatch analysis.

Notifying the SSTP and anglers of recaptures ?
Rather than sending recapture details by post anglers will be able to enter details of a caught fish online by PC and receive details of any previous activity and the original ‘tagger’ will be notified that his/her fish has been recaptured, along with any other data, like days at liberty, distance travelled, weight/length gain, etc;

Will the data I provide be safe?
The SSTP will accumulate the tagging information on a database and this data will NOT be distributed to any group or body with any commercial fishing interests.

The control of data will be closely guarded, and only available in its ‘raw and total’ format to a limited number of ‘approved’ scientists. Any information given out from the database will be on a “Need to know” basis. A lot of effort you might ask, but we wish to allay fears that the information may be used by commercial fishing interests to the further detriment of stock levels

Further studies will be carried out from time to time on the whole database by selected ‘marine biologists’, who will be working directly for the tagging programme, their reports will also be made available to the taggers.

Will the SSTP be starting from scratch?
The Glasgow museum and the UK Shark Tagging Programme have agreed to input their existing data concerning Scottish sharks into the new database.

Special Events
The SSTP will run a series of events throughout the year to increase the number of fish caught and tagged.
The events also have a good social side and many tales are told, over a beer or two, about the “ones that got away”

Tiger Shark snatches underwater camera from diver's hands

Karin Brussaard recalls "There were about six or seven tiger sharks down there and we couldn't believe our luck. We were having a great time photographing them all until one diver swam towards one of them trying to get a better shot.

The shark suddenly seemed to get angry and snatched the camera right out of his hands."

Tiger sharks are considered to be one of the most dangerous shark species in the world and are responsible for many recorded attacks on humans, second only to the great white shark.

These remarkable pictures show the moment a tiger shark snatched an expensive camera from the hands of a petrified photographer during an underwater diving expedition in the Bahamas.

After photographer Karin Brussaard took several photos, the shark decided enough was enough and grabbed the equipment in its jaws before swimming off

Brussaard, from the Netherlands, said: "Luckily it did drop it eventually and remarkably the camera only seemed to have a couple of scratches on it"

Swimming with wild reef sharks - Shark Therapy - BBC video

Hammerhead sharks - Evolutionary process

For over a century, scientists have speculated why hammerheads evolved such an odd shape and whether having eyes so far apart would enhance their vision.

In 1942 a leading authority on sharks, Gordon Walls, suggested the position of the shark's eyes prevented it from having binocular vision but others have argued exactly the opposite, saying the animals must have enhanced eyesight.

Now, hammerhead sharks have had their first eye examination, and it has laid the debate to rest. Sharks with wider heads have better binocular vision – all the better to track fast-moving prey like squid with far more accuracy than sharks with close-set eyes.

The research also shows that hammerheads – among other sharks – have a 360-degree view of the world in the vertical plane, allowing them to simultaneously see prey above and below them.

Glow-in-the-Dark Lantern Shark

National Geographic: Crittercam - Swim with the Penguins