Намерена е риба, която ходи като четирикрако животно

[Last roman]

Екип от учени идентифицираха уникални анатомични характеристики на един вид сляпа пещерна риба в Тайланд, които позволяват на рибата да ходи и да се катери по водопади по начин, сравним с четириногите бозайници или земноводни или т. нар. тетраподи.

Изненадващите констатации на изследователите от Технологичния институт на Ню Джърси (New Jersey Institute of Technology - NJIT) са публикувани в Nature.

Наблюдаваните досега други "ходещи" риби се придвижват с помощта на перките си, а Cryptotora thamicola, която е обект на изследването, се движи като саламандър.

Необичайният тазов пояс

Уникалното, това което отличава тази сляпа пешерна риба от другите "ходещи" риби е, че тя има особена анатомия - тя използва за ходенето си необичайния си таз. Тазовият пояс на рибата има подобни морфологични характеристики като тези на сухоземните гръбначни.

"Тя притежава морфологични характеристики, които преди това са приписвани само на четириногите. Тазът и гръбначният стълб на тази риба позволяват да подкрепят теглото тялото й и предоставят достатъчно място за закрепване на мускули за ходене" - обяснява съавторът на изследването Брук E. Флейминг (Brooke E. Flammang).

"Ние открихме, че Cryptotora има тазов пояс, който е свързан с аксиалния скелет чрез връзка с хипертрофирано ребро на седмия прешлен"- пише в изследването.

 

^{Компютърна микротомография на Cryptotora thamicola. Източник: "Tetrapod-like pelvic girdle in a walking cavefish" / Brooke E. Flammang, Apinun Suvarnaraksha, Julie Markiewicz & Daphne Soares.}

Откриването на такава способност не е наблюдавана при други риби и добавя още информация за това как анатомията трябва да е еволюирала, за да позволи на видовете да ходят по земята.

^{Компютърна микротомография на златна рибка. Вижда се разликата с Cryptotora thamicola. Източник: "Tetrapod-like pelvic girdle in a walking cavefish" / Brooke E. Flammang, Apinun Suvarnaraksha, Julie Markiewicz & Daphne Soares.}

Въпреки че наблюдения в природата на тази пещерна рибка са документални и преди, това става много трудно, заради недостъпността на местата, които обитава - пещерите на северен Тайланд, съобщава ВigТhink.

Поради това не е проучена до момента и последните научни изследвания хвърлят съвсем нова светлина върху уникалността на това неуловимо същество.

"От еволюционна гледна точка, това е огромна констатация," - заяви съавторът на изследването Брук E. Флейминг (Brooke E. Flammang). "Това е една от първите живи риби, която действа по начина, който смятаме, че трябва да са действали, когато рибите са еволюирали от течна среда към сухоземна".

Еволюцията на четириногите започва преди около 395 милиона години по време на периода девон, време традиционно известно като "Епохата на рибите". Когато четириногите се приспособили да живеят на сушата, телата им се променили. Тайландската пещерна риба е очарователно напомняне и потвърждение на нашите знания за това време.

 

ВИДЕО КЪМ НОВИНАТА

 

http://nauka.offnews.bg/news/a_0/a_48656.html?preview=ok

[Last roman]

продължаваме по темата:

Fish may have evolved to live on land more than 30 times

http://www.sciencemag.org/news/2016/06/fish-may-have-evolved-live-land-more-30-times?utm_source=newsfromscience&utm_medium=facebook-text&utm_campaign=fishvolve-5103

[Last roman]

Още един рибок, който е тръгнал 'буквало' по утъпканата пътека на сухоземния живот:

If A Fish Grows Up On Land, Will It Learn To Walk?

Walk This Way

A Polypterus senegalus fish on land.

The old idiom about “being a fish out of water” just lost some of its luster. Researchers from McGill University in Canada successfully trained a group of fish to live on land and strut around.

The idea was to simulate what might have happened 400 million years ago, when the first group of ancient fish moved from water to land, eventually evolving into the amphibians, reptiles, birds and other animals roaming the Earth today. The researchers wanted to see if their land-dwelling fish looked and behaved similarly to the ancient fish, based on what has been learned about them from fossil records.

For their experiment, the research team raised 111 juvenile Polypterus senegalus – African fish also known as the “dinosaur eel” -- on land. These fish already look a lot like the ancient fish that evolved millions of years ago, and they’re already capable of “walking” with their fins and breathing air. According to the Verge, their terrestrial environment had mesh flooring covered in pebbles, as well as 3 millimeters of water, so the fish didn’t dry out completely.

Video analysis of the fish showed that they did indeed change significantly from the water-dwelling control group; they learned to place their fins closer to their bodies, helping them to walk more effectively, and they lifted their heads higher than fish in an aquatic environment. Even their skeletons changed, becoming more elongated and forming stronger attachments across the chest (perhaps to increase walking support).

Many of these changes are similar to what has been inferred from fish fossil records, leading the researchers to "hypothesize that the behavioral changes we see also reflect what may have occurred when fossil fish first walked with their fins on land”, says Hans Larsson, a collaborator on the project at McGill. But are we sure teaching fish to walk is such a good idea? It's time we all revisited The Creature from the Black Lagoon.

http://www.popsci.com/article/science/if-fish-grows-land-will-it-learn-walk?con=TrueAnthem&dom=fb&src=SOC&utm_campaign=&utm_content=5889fb07b8a9fe00095f70a7&utm_medium=&utm_source

Редактирано Януари 26, 2017 от Last roman

[Last roman]

These fish are evolving right now to become land-dwellers

 

Chris Fulton, Australian National University

By Alice Klein

It’s a literal case of fish out of water. Blenny fish in the South Pacific Ocean are gradually relocating to land to escape their aquatic predators, in an example of evolution in action.

Fish first began crawling onto dry land about 400 million years ago, kicking off an evolutionary chain of events that led to humans. But their reasons for exiting the sea have been uncertain.

To look for clues, Terry Ord at the University of New South Wales in Australia and his colleagues have been studying several species of blenny fish or ‘blennies’ at Rarotonga, the largest of the Cook Islands.

 

 

 

At low tide, blennies are commonly found swimming in rock pools around the edges of the island. But when high tide moves in, they climb up to dry land and shuffle around the rocks until the tide retreats.

The researchers found that this is most likely to avoid predators that swim in with the rising tide – mainly bigger fish like flounders and lionfish.

To test what would happen if blennies did not have an escape plan, they made plasticine models and submerged them in the sea. The blenny mimics ended up with puncture wounds, bite marks and chunks missing.

Island life

Of course, there are still dangers for blennies on land – the researchers observed the occasional bird attack – but predation risk on land is about a third that of underwater.

What’s more, moving onto land has additional benefits for blennies. Holes in the rocks provide sheltered nests for laying eggs, and they can maintain their diet of algae and bacteria by nibbling them off rocks.

In fact, several species of blenny fish at Rarotonga and elsewhere have already made the full transition to land-dwelling species. They continue to breathe with their gills, but have developed stronger tail fins that allow them to jump from rock to rock.

Other fish families have also crossed the land-water interface over the last 400 million years – about 33 families in total.

Ord believes that many evolutionary processes – not just the transition of fish to land – have been driven by the need to escape predators. It is often assumed that animals move homes to find new sources of food, but in many cases, escaping predators is a stronger impetus, he says.

“If you never look over the fence, you’ll never know that the grass is greener,” he says. “However, if you’re forced to the other side to escape something, you may then realise it has additional benefits and want to stay there and adapt.”

Mike Lee at Flinders University in Adelaide, Australia, agrees that this escape instinct is a powerful driver. “The convergent evolution of terrestriality in blennies on oceanic islands – which are relatively free of land predators – is definitely strong evidence that they are climbing out of the water to escape being eaten,” he says.

However, the jury is still out on whether predator escape is a more compelling reason to relocate than the desire to find more food, says Lee.

“A lot of aquatic reptiles and mammals seem to be attracted to food underwater, including iguanas, sea snakes and sea otters,” he says. “They’d rather eat well, even if it means they are more likely to be eaten.”

Journal reference: The American Naturalist, DOI: 10.1086/691155