Prehistoric Shark Exhibited Migratory Spawning Behavior Similar to Salmon

Artist impression of Prehistoric Bandringa Shark
Credit: John Megahan, University of Michigan

Paleontologist have discovered evidence of the migratory habit of the prehistoric shark, Bandringa. Fossil evidence show that the prehistoric shark bred in the ocean and migrated to freshwater.

Modern day sharks are not known to do follow this habit and the discovery is the only known example of a freshwater to saltwater shark migration.

Their spawning behavior left evidence of the earliest known shark nursery in the preserved fossilized egg cases and juvenile sharks found in the sediments.

The Bandringa is one of the closest relative of modern day shark and is similar to the sawfish and paddlefish. Just like the two, Bandringa has a spoon-billed snout up to half its body length. Young Bandringa sharks are about 4 to 6 inches long but can grow up to 10 feet upon maturity.

The 310 million year old shark was first found in fossil deposits in Mazon Creek, Illinois. It is a bottom-feeding predator and are known for for their extremely long spoonbill snouts. Because adult fossils have been only found at freshwater locations, it is believed that the shark lived exclusively in freshwater swamps and rivers.

Fossil of Helicoprion Reveals Secrets of Circular-saw like Teeth

An X-ray CT scan of a well preserved fossil of the Helicoprion reveals how the creature really looks like after years of conjecture.

The Helicoprion was a bizarre creature that lived during the Carboniferous Period around 270 to 300 million years ago. It was believed to be part of the shark family. It had a very distinct and unusual feature in that fossils show that its lower jaw had a circular-saw like set of sharp serrated teeth.

There was much debate on how the creature would look like with this set of teeth. The first fossils discovered of the Helicoprion were very incomplete and didn't really indicate how the creature would really look like. Because of that, there were many theories on how this circular set of teeth fit in with the Helicoprion.

There were some that theorized that the teeth were attached and curled up to a tongue like organ that can extend out similar to an elephant's trunk. Other's believe that the teeth were situated inside the creature's mouth. Other's even suggested that the circular groupings were located on the tail of the Helicoprion.

Although some discovered fossils showed hints of cartilaginous tissue, none have included the braincase or postcranial parts of these fish.

Wave Glider Robot Track Ocean's Great White Sharks And Shares Info With Public

Shark Net app available free
Credit: Stanford University

Sea-surfing 'wave glider' robot deployed to help track white sharks in the Pacific

A sleek, unmanned Wave Glider robot has been deployed off the US coast near San Francisco -- the latest addition to an arsenal of ocean observing technologies revealing in real time the mysterious travels of great white sharks and other magnificent marine creatures.

The self-propelled, solar-powered glider is part of a new network of data receivers on fixed buoys will pick up signals from acoustic tags on animals passing within 1,000 feet and transmit the data to a research team on shore, led by Stanford University Marine Sciences Prof. Barbara Block.

The long-lasting, relatively inexpensive acoustic tags and the local array of both fixed and mobile ocean transmitters will fine tune 12 years of insights gleaned from satellite-connected tags used to follow thousands of animals throughout their entire Pacific journeys.

Dr. Block and her team are on a mission to create a "wired ocean" where live feeds of predator movements are relayed by a series of "ocean WiFi hotspots" on moored buoys and self-propelled Wave Gliders carrying acoustic receivers.

The technology is central to Dr. Block's "Blue Serengeti Initiative," which builds on the Tagging of Pacific Predators (TOPP) project, part of the international Census of Marine Life (2000-2010).

"Our goal is to use revolutionary technology that increases our capacity to observe our oceans and census populations, improve fisheries management models, and monitor animal responses to climate change," says Dr. Block.

Wave Glider Carey and Dr.Barbara Block & Keith Kreider
Credit: Stanford University

The bright yellow, seven-foot long Wave Glider and fixed buoys will transmit data this summer and fall from animals off the California coast near San Francisco, between Monterey Bay and Tomales Point. In time Dr. Block hopes to extend this ocean observing network down the entire west coast of North America, tracking animals that range in size from salmon smolts to large ocean going predators such as white, mako and salmon sharks.

Says Dan Basta, Director of the Office of National Marine Sanctuaries, part of the National Oceanic and Atmospheric Administration's National Ocean Service: "Animals may tell us more about how the world works and is changing then any other source of knowledge."

Importantly, the public can now follow the tracking of animals in real time on a smartphone and tablet computer app.

"Shark Net," a new iOS app available free of charge at the Apple app store, was created by Dr. Block and her colleagues with developers from TOPP, EarthNC and Gaia GPS to enable a direct, personal connection between the public and wild marine animals and to raise public awareness of the ocean wilderness teeming with life just off North America's West Coast.

Population of Reef Sharks Plummet By More Than 90 Percent In Certain Areas

Curious gray reef sharks (Carcharhinus amlyrhynchos) at Kure Atoll in the Papahanaumokuakea Marine National Monument, Hawaii were studied as part of a study published April 25 in the journal Conservation Biology. An international team of marine scientists provide the first estimates of reef shark losses in the Pacific Ocean using underwater surveys conducted over the past decade across 46 US Pacific islands and atolls, as part of NOAA's extensive Pacific Reef Assessment and Monitoring Program. The team compared reef shark numbers at reefs spanning from heavily impacted ones to those among the world's most pristine. The results are sobering.

Reef sharks are found around coral reefs and in tropical and warm temperate waters in the Indo-Pacific region.

Reef sharks are spread across different shark species. Species classified as reef sharks are

• Blacktip reef shark (Carcharhinus melanopterus)
• Caribbean reef shark (Carcharhinus perezii)
• Grey reef shark (Carcharhinus amblyrhynchos)
• Whitetip reef shark (Triaenodon obesus)

Scientists provide first large-scale estimate of reef shark losses in the Pacific Ocean

Many shark populations have plummeted in the past three decades as a result of excessive harvesting – for their fins, as an incidental catch of fisheries targeting other species, and in recreational fisheries. This is particularly true for oceanic species. However, until now, a lack of data prevented scientists from properly quantifying the status of Pacific reef sharks at a large geographic scale.

In a study published online April 27 in the journal Conservation Biology, an international team of marine scientists provide the first estimates of reef shark losses in the Pacific Ocean. Using underwater surveys conducted over the past decade across 46 U.S. Pacific islands and atolls, as part of NOAA's extensive Pacific Reef Assessment and Monitoring Program, the team compared reef shark numbers at reefs spanning from heavily impacted ones to those among the world's most pristine.