Ruby seadragons, first ever video


This video says about itself:

12 January 2017

Researchers at Scripps Oceanography and the Western Australian Museum capture on video the first-ever field sighting of the newly discovered third species of seadragon. As they observed two Ruby Seadragons on video for nearly 30 minutes, the scientists uncovered new details about their anatomy, habitat, and behavior.

See also here.

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.”

Blue tilapia kiss in Florida, USA


This video from the USA says about itself:

6 January 2017

The wild Blue Tilapia spawn is on in Florida and its time to pucker up! Males are digging nests along the banks of the St. Johns River in central Florida and attracting females. Blue Tilapia are mouth brooders and females keep the eggs in their mouths for safety. Males sometime fight with their mouths, but this is a very gentle and careful mouth to mouth contact between two large Tilapia, if an expert would like to weigh in on what they are really doing I’m all ears. Many birds in the background – these fish are too big to worry about being eaten by big herons, but alligators – that’s another story!

Blue Tilapia: Oreochromis aureus

Appearance:

Young nondescript gray with a black spot at rear of dorsal fin; adults generally blue-gray shading to white on the belly; borders of dorsal and caudal fins with red to pink borders; broken lateral line and the spiny dorsal fin is joined to the soft dorsal fin. In central Florida, anglers can assume every tilapia they observe in fresh water is a blue, and any tilapia over 3 pounds is also likely a blue tilapia.

Similar Species

Female Mozambique tilapia (O. mossambicus) nearly identical, but doesn’t grow as large and currently only occurs in coastal areas south of Titusville; possible hybridization between blue and Mozambique tilapias further complicates identification; male Mozambique tilapia easily distinguished by large mouth and black coloration when breeding.

Habitat:

Widespread and abundant in Florida; found in fertile lakes, ponds, rivers, streams, and canals. It is tolerant of saltwater and found in some near shore marine habitats, such as Tampa Bay.

Native to north Africa and the Middle East.

Save sea trout in England


This video says about itself:

14 December 2009

Three sea trout spawning in December 2009 on a small stream tributary of the Sussex Ouse. There are two larger fish in the redd spawning (a male and a female up to about 8lb) and also a smaller chancer male about 40cm downstream of them. When the larger male is not so active the smaller one darts in and tries to fertilise the female’s eggs, and is then usually seen off by the larger male.

By Dave Bangs in England:

Another native species under threat

Thursday 5th January 2017

Sussex’s native sea trout have returned to Britain’s freshwater rivers and streams since before the last ice age, yet their habitats are being destroyed, writes DAVE BANGS

FOR ME, there is only one native British fish more beautiful than the Atlantic salmon, and that’s the sea trout of the Sussex race.

I should explain that the sea trout is a particular type of our native trout species which leaves its birthplace in our little streams to roam the sea before returning to its natal stream to spawn.

Many of its close relatives choose to stay all their lives at home, however, and they are known as the brown trout or “brownies.”

They tend to be much smaller because their freshwater diet is poorer than a sea-going diet.

Our Sussex sea trout can be as big as salmon and spawn later than other races of their kind.

You find their gravel nests around Christmas time, especially in our chalk streams.

At deepest dusk, if you are lucky, you may see a giant “hen” fish lying in the scrape she has dug, whilst the “cock” fish sidle up to her to mix their milt (sperm) with her roe (eggs).

Their backs emerge from the shallow riffles like surfacing submarines, whilst the water breaks over them.

In their breeding finery they are spotted brightest pink and black and grow to 2.5ft long and over 12lb in weight.

These fish have probably been returning annually to our local rivers from their rich sea feeding waters since long before the end of the ice age some 12,000 years ago.

Their migrations have marked the retreat of glaciers and tundra and the greening of our 30-mile wide Wealden vale to the lush “salad bowl” of trees and meadows that it is today.

Things are not good for these ancient beasts, however, whose numbers may be counted nowadays in the hundreds rather than the teeming thousands of the deep past.

Obstructing weirs have been built along most streams to facilitate farmers’ irrigation and commercial navigation, to make mill ponds, and manage coarse fisheries.

Sewage works and farmers’ pollutions periodically plague the rivers.

As the human population of the south east of England swells in response to capitalism’s unequal regional development new housing requires more and more freshwater, and the head streams shrivel and dry back towards the Rivers Adur and Ouse main channels.

Only the perennial springs along the base of the South Downs scarp give certainty of flow to the crystal clear chalk streams.

There is however no certainty about the future of those streams either.

This year a “posh food” business sought to bring another rare species — Siberian sturgeon — to the meadows next to a sea trout nursery stream of the Ouse, to stock the newly dug ponds of a “caviar farm” (caviar is sturgeon eggs) bringing new risks to the precious water supply of these streams, breaking the open riparian corridor and threatening new biosecurity measures and exclusion fences.

The residents who led the campaign against the fish farm were a cross section of our modern countryside: rich bankers and business millionaires.

Their campaign slogan: “Wrong Fish, Wrong Place,” attracted sarcastic responses from those urban folk who felt the sturgeon farmer was not the only person whose entitlement to this countryside they wished to challenge.

We won that time, despite the social narrowness of the campaign and Lewes district council rejected the fish farm’s planning application.

Yet within a few days, far worse disaster struck.

At dead of night a system failure at the dairy unit of nearby Plumpton Agricultural College emptied the contents, it is estimated, of a whole slurry tank into the headwaters of the Plumpton Mill Stream.

A kilometre-long “slug” of ink-black dung and urine rolled down into the Bevern stream and along to the confluence with the River Ouse at Barcombe Mills.

Every brown and sea trout in its path and every other fish — minnow, stone loach, bullhead, eel, chub and the only known breeding colony of brook lamprey in these streams — were suffocated.

In one night, the streams which the Ouse and Adur Rivers Trust had been working to conserve for 30 years were stripped of their higher life forms.

It may take another generation to restore them.

This is not the first time Plumpton College has polluted our streams. Anglers and river workers report pollution incidents back as far as they can remember: nine incidents just since 2011.

Day and night, the workers of the Environment Agency struggled to contain the pollution with sandbags, oxygenators and water pumps.

But the damage had been done.

Will the magnificent beasts of these little streams survive beyond our time?

That is up to us. It is not up to millionaire rural residents and businesses. It is not up to polluting private rural colleges.

It is up to us — from our towns and cities — to reclaim and restore our natural heritage.

Mandarin duck and fish in Dutch Gelderland


This autumn 2016 videos shows a mandarin duck and fish in the nature reserve around Kreelse plas lake in Dutch Gelderland province.

Spawning mandarinfish video


This video says about itself:

16 December 2016

Even experienced divers rarely get to see the Mandarinfish, a colorful reef fish that is so shy, it only comes out of hiding for a half-hour a day. Jonathan travels to the south Pacific to film spawning Mandarinfish and witnesses an incredible secret ritual.

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.