New hammerhead shark species discovery in Belize


This video says about itself:

5 February 2017

Scientists have discovered a new population of miniature sharks off the coast of Belize. The bonnethead, a small species of hammerhead shark, can be found in many spots around the Caribbean. However, the new shark is an entirely different species based on large genetic differences between them and other bonnetheads. Bonnethead sharks are commercially fished in the United States, throughout the Caribbean and in South America. The recording of the new shark was reportedly made during a 2016 shark tagging expedition.

From The Reporter in Belize:

New hammerhead shark species found in Belize

Posted by The Reporter newspaper on February 9, 2017 at 10:42 am

By Benjamin Flowers

Shark researchers have discovered a new species of shark in Belize.

Researchers from Florida International University (FIU) were conducting DNA sequencing on bonnet head sharks, a species of hammer head sharks, when they made the discovery.

The bonnet head shark is found in the Caribbean, Latin America, and the United States; however, the DNA of the species found in Belize did not match that of the bonnet heads found anywhere else. The bonnet heads found in Belize, which have yet to be named, have the same physical appearance as its counterparts within the region, but have large genetic differences.

Evaluating the DNA analysis conducted by Andrew Fields from Stony Brook University, FIU researchers estimated that the bonnet head sharks around the nation stopped interbreeding with those from Mexico, the United States and the Bahamas several million years ago.

Demian Chapman, lead researcher on the team that made the discovery, said that the find raises concerns about the sustainability measures in place to keep the species from extinction. While the bonnet head is ranked at “Least Concern” for extinction risk by the International Union for the Conservation of Nature, the union made the classification assuming there was a single species of bonnet head.

“Now we have to define the range of each of these species individually and assess them independently against where the potential threats are,” Chapman said.

Chapman who is currently leading a shark survey project called Global Finprint, believes that the discovery could be the door way to finding even more new species of sharks.

Global Finprint is an initiative seeking to determine the cause for the decreasing number of sharks and rays.

Fish in ocean food chain, video


This 3 February 2017 video says about itself:

Predators Attack Fish Bait Ball – Blue Planet – BBC Earth

3 feb. 2017

Small fish swim at phenomenal speed and form a daunting bait ball in a desperate attempt to ward off hungry predators [like sharks].

Pacific sharks on video


This video says about itself:

Thousands Of Sharks Visit A Sea Mount – Blue Planet – BBC Earth

27 January 2017

In the Pacific, a tiny island 300 miles away from the shore hides a giant mountain beneath the waves that forms a home for thousands of plankton feeding fish. These fish attract tuna, and the tuna attract thousands of sharks. Watch this video to learn more about this fascinating food chain, and hear some weird but true facts about the visiting hammerhead sharks..

Taken From Blue Planet Series 1.

How hagfish survive shark attacks


This video says about itself:

Hagfish predatory behaviour and slime defence mechanism

26 October 2011

Hagfishes (Myxinidae) are a family of jawless marine pre-vertebrates. Those video images taken in New Zealand revealed that hagfishes are able to choke their would-be predators with gill-clogging slime.It also shows that hagfishes are actively preying on other fish in New Zealand waters.

The video is part of a scientific paper describing this newly discovered behaviour which can be downloaded online.

From Science News:

Unusually loose skin helps hagfish survive shark attacks

Slip-sliding outer covering also aids in Houdini escapes

By Susan Milius

6:26pm, January 6, 2017

NEW ORLEANS, La. – Skin that mostly hangs loose around hagfishes proves handy for living through a shark attack or wriggling through a crevice.

The skin on hagfishes’ long, sausage-style bodies is attached in a line down the center of their backs and in flexible connections where glands release slime, explained Douglas Fudge of Chapman University in Orange, Calif. This floating skin easily slip-slides in various directions. A shark tooth can puncture the skin but not stab into the muscle below. And a shark attack is just one of the crises when loose skin can help, Fudge reported January 5 at the annual meeting of the Society for Integrative and Comparative Biology.

Hagfishes can fend off an attacking shark by quick-releasing a cloud of slime. Yet video of such events shows that a shark can land a bite before getting slimed. To figure out how hagfishes might survive such wounds, Fudge and colleagues used an indoor guillotine to drop a large mako shark tooth into hagfish carcasses. With the skin in its naturally loose state, the tooth readily punched through skin but slipped away from stabbing into the body of either the Atlantic (Myxine glutinosa) or Pacific (Eptatretus stoutii) hagfish species.

But when the researchers glued the skin firmly to the hagfish muscle so the skin couldn’t slip, the tooth typically plunged into inner tissue. For comparison, the researchers tested lampreys, which are similarly tube-shaped but with skin well-fastened to their innards. When the guillotine dropped on them, the tooth often stabbed directly into flesh.

The finding makes sense to Theodore Uyeno of Valdosta State University in Georgia, whose laboratory work suggests how loose skin might work in minimizing damage from shark bites. He and colleagues have tested how hard it is to puncture swatches of skin from both the Atlantic and Pacific species. As is true for many other materials, punching through a swatch of hagfish skin held taut didn’t take as long as punching through skin patches allowed to go slack, he said in a January 5 presentation at the meeting. Even a slight delay when a sharp point bears down on baggy skin might allow the hagfish to start dodging and sliming.

But Michelle Graham, who studies locomotion in flying snakes at Virginia Tech, wondered if puncture wounds would be a drawback to such a defense. A hagfish that avoids a deep stab could still lose blood from the skin puncture. That’s true, said Fudge, but the loss doesn’t seem to be great. Hagfish have unusually low blood pressure, and video of real attacks doesn’t show great gushes.

Hagfish blood also plays a part in another benefit of loose skin — an unusual ability to wiggle through cracks, Fudge reported in a second talk at the meeting. One of his students built an adjustable crevice and found that both Atlantic and Pacific hagfishes can contort themselves through slits only half as wide as their original body diameter. Videos show skin bulging out to the rear as the strong pinch of the opening forces blood backward.

The cavity just under a hagfish’s skin can hold roughly a third of its blood. Forcing that reservoir backward can help shrink the body diameter. Fortunately the inner body tapers at the end, Fudge said. So as blood builds up, “they don’t explode.”

Sand tiger sharks of North Carolina, USA


This video says about itself:

2 December 2016

Jonathan heads to North Carolina to explore the offshore shipwrecks of the “Graveyard of the Atlantic” which have become home to Sand Tiger sharks. The sharks are unwitting bodyguards to small fish seeking protection from predators and have developed a clever way to hide from the fish and to hover with perfect buoyancy control.

Curaçao sharks and cattle


This Dutch video is about sharks around the Caribbean island Curaçao, and cattle in Dutch nature reserve Klompenwaard.