This video is about the anglerfish.
This video is about the anglerfish.
The Dutch ship Pelagia is doing research about the coral reefs of the Saba Bank. Near the island, there are pollution problems. However, the ship also discovered a so far unknown reef which is in good condition.
This 2014 video features a closer inspection of some of the coral reef fauna found at Saba.
This video is about the 2018 Pelagia research.
This 2015 video says about itself:
Hogfish at Cleaning Station – Turks and Caicos
A very rare sighting to capture on camera, a hogfish at a cleaning station. After approaching the Hogfish very slowly and passively we managed to capture some fantastic footage of the hogfish being cleaned by some small reef fish. Whilst the hogfish hangs motionless the other fish enter and clean inside of the mouth and gill area. Shot on a GoPro Hero 3 Silver Edition by Kieran Bown.
From Duke University in the USA:
Color-changing hogfish ‘sees’ with its skin
Fish’s skin senses light differently from eyes
March 12, 2018
Summary: The hogfish can go from white to reddish in milliseconds as it adjusts to shifting conditions in the ocean. Scientists have long suspected that animals with quick-changing colors don’t just rely on their eyes to tune their appearance to their surroundings — they also sense light with their skin. But exactly how remains a mystery. A study reveals that hogfish skin senses light differently from eyes.
Some animals are quick-change artists. Take the hogfish, a pointy-snouted reef fish that can go from pearly white to mottled brown to reddish in a matter of milliseconds as it adjusts to shifting conditions on the ocean floor.
Scientists have long suspected that animals with quick-changing colors don’t just rely on their eyes to tune their appearance to their surroundings — they also sense light with their skin. But exactly how “skin vision” works remains a mystery.
Now, genetic analysis of hogfish reveals new evidence to explain how they do it. In a new study, Duke University researchers show that hogfish skin senses light differently from eyes.
The results suggest that light-sensing evolved separately in the two tissues, said Lori Schweikert, a postdoctoral scholar with Sönke Johnsen, biology professor at Duke.
With “dermal photoreception”, as it is called, the skin doesn’t enable animals to perceive details like they do with their eyes, Schweikert said. But it may be sensitive to changes in brightness or wavelength, such as moving shadows cast by approaching predators, or light fluctuations associated with different times of day.
Schweikert, Johnsen and Duke postdoctoral associate Bob Fitak focused on the hogfish, or Lachnolaimus maximus, which spends its time in shallow waters and coral reefs in the western Atlantic Ocean, from Nova Scotia to northern South America. It can make its skin whitish to blend in with the sandy bottom of the ocean floor and hide from predators or ambush prey. Or it can take on a bright, contrasting pattern to look threatening or attract a mate.
The key to these makeovers are special pigment-containing cells called chromatophores, which, when activated by light, can spread their pigments out or bunch them up to change the skin’s overall color or pattern.
The researchers took pieces of skin and retina from a single female hogfish caught off the Florida Keys and analyzed all of its gene readouts, or RNA transcripts, to see which genes were switched on in each tissue.
But Schweikert and colleagues found that hogfish skin works differently. Almost none of the genes involved in light detection in the hogfish’s eyes were activated in the skin. Instead, the data suggest that hogfish skin relies on an alternative molecular pathway to sense light, a chain reaction involving a molecule called cyclic AMP.
Just how the hogfish’s “skin vision” supplements input from the eyes to monitor light in their surroundings and bring about a color change remains unclear, Schweikert said. Light-sensing skin could provide information about conditions beyond the animal’s field of view, or outside the range of wavelengths that the eye can pick up.
Together with previous studies, “the results suggest that fish have found a new way to ‘see’ with their skin and change color quickly”, Schweikert said.
This 2012 video says about itself:
The cleaner wrasse helps out bigger fish by eating any parasites and dead tissue that might be clinging to them. In exchange for the wrasse’s assistance, the bigger fish refrain from snacking on them. The wrasse gets a free meal from the cod, and the cod stays healthier because of the wrasse.
Relationships like this, where different plants or animals work together and help each other out is called “mutualism” because both organisms mutually benefit from the other being around. In fact, these little cleaner wrasses are so good at what they do, that these bigger fish will actually seek them out– they’ll deliberately pay visits to wrasse cleaning stations along reefs, much the same way people will line up to have their cars cleaned on a nice summer day!
From the Université de Montréal in Canada:
Staying clean keeps seafish smart
March 7, 2018
“Vet” service provided by smaller fish is key to keeping coral reefs healthy, a Canadian study finds.
A team of international researchers led by a Canadian biologist has found that infection with parasites makes it harder for seafish living in coral reefs to think.
The study, conducted at the Lizard Island Research Station in Australia and led by Assistant Professor Sandra Binning of Université de Montréal’s Department of Biological Sciences, was published today in Proceedings of the Royal Society B: Biological Sciences.
It highlights the important role of both parasites and cleaning organisms in the decision-making abilities of reef fish.
Binning and her team found that sick seafish can get well again by seeking out other animals like the blue-streaked “cleaner wrasse”, a common aquarium fish that eats harmful parasites off their “clients”, helping keep them healthy.
“We collected wild damselfish with or without access to cleaner wrasse and tested their ability to solve a feeding test in the lab”, Binning recalled. “We then compared their performance to fish that we infected with parasites experimentally.”
“We found that infection with parasites, especially in high numbers, really affects the ability of fish to learn.”
These results may not be surprising to anyone who’s been sick and tried to do activities requiring thinking and concentration. “When we’re sick, our body diverts resources away from our brain towards fighting off the infection”, Binning noted. “This makes it harder for us to think and learn.”
Humans may also benefit from staying parasite-free. “Studies have found that schoolchildren with stomach worms perform worse on standardized tests that their parasite-free peers,” said Binning. “Treating these kids with anti-parasite medication improves their performance.”
Although fish can’t take medication when they’re feeling under the weather, they can enlist the help of cleaners to help rid them of their parasites. This access to cleaning services can dramatically improve a fish’s performance in a learning test.
According to Dr. Binning, “cleaner wrasse act like the vets of the sea. Clients visit cleaners to get their parasites removed, and this helps boost their ability to think and solve the test.”
Interactions with cleaner wrasse are also known to reduce client stress levels and increase local recruitment of coral reef fishes.
However, this vital role in maintaining healthy reef communities may be under threat: cleaner wrasse are among the top marine fishes caught for the aquarium industry, due to their colourful patterns and charismatic behaviour.
“It’s important that we understand the impacts of reduced access to cleaners on client fishes”, said Binning. “Cleaners may not be the largest or most abundant fish on the reef, but they affect the well-being of thousands of their clients. This needs to be taken into consideration when setting collection limits and managing marine parks.”
The study was done in collaboration with several groups of researchers: Derek Sun and Alexandra Grutter of the University of Queensland in Australia; Dominique Roche, Simona Colosio and Redouan Bshary of the University of Neuchatel in Switzerland; and Joanna Miest of the University of Greenwich in the U.K.
This 2013 aquarium video is called Neolamprologus obscurus.
How a fish species in Lake Tanganyika works together to secure additional food sources
March 6, 2018
Cooperative behaviour to acquire food resources has been observed in hunting carnivores and web-building social spiders. Now researchers have found comparable behaviours in a fish species. A tiny striped fish called Neolamprologus obscurus only found in Lake Tanganyika in Zambia excavates stones to create shelter and increase the abundance of food for all fish in the group. Led by Hirokazu Tanaka of the University of Bern in Switzerland and the Osaka City University in Japan, this study is the first to document how team work in fish helps them to acquire more food. The research is published in Springer’s journal Behavioral Ecology and Sociobiology.
Neolamprologus obscurus is a highly sociable species of cichlid found only in the southern reaches of Lake Tanyanika. These zebra-striped fish feed mainly on shrimp and other invertebrates found along the bottom of the lake. At night, shrimp move into the water column, but by dawn they sink back to the lake bottom to hide in crevices and holes, including the shelters that the fish have dug out under stones. Such excavation work is always done as a group, as is subsequent maintenance efforts. Breeding fish seldom leave these safe havens and are supported by up to ten helpers from their family group. The helpers protect the brood, and constantly remove sand and debris that fall into the cavities.
“The function of these excavated cavities is much like that of the webs of social spiders, which live in groups and share the trapped prey among group members,” explains Tanaka.
In this study, Tanaka and his colleagues wanted to find out if the size of the cavities at the bottom of the lake relate to the abundance of food available in the area, and if the presence of helpers influences the size. Through hours of scuba diving in Lake Tanyanika, the researchers created artificial cavities and examined the stomach contents of some of the fish. In another experiment, the researchers removed helpers that were assisting breeding fish. Within a week, enough sand had fallen into the cavities to decidedly shrink these spaces. This effect was augmented when the helpers removed were big.
One of the key findings was that the size of an excavated crevice had an influence on the amount of shrimps that subsequently gathered in it. When there were more helpers around, the space that could be created was bigger and more shrimps could be gathered.
“Helpers in Neolamprologus obscurus extend and maintain the excavated cavities, and by doing so, contribute to an increase in food abundance inside the territory of breeding females”, explains Tanaka.
“Fish living in groups may be able to increase and maintain considerably larger excavated cavities per capita compared to solitary living fish. Consequently, group living enables Neolamprologus obscurus to efficiently increase the prey abundance in their territory. This increases the body condition and future reproductive success of breeders and/or helpers”, adds Tanaka, who suggests that there is a clear benefit to group living for this species of fish.
This Associated Press video says about itself:
31 July 2015
South Korea is banning imports of all fishery products from Japan’s Fukushima region because of what it calls growing public worry over radiation-contaminated food that has reportedly prompted a sharp decline in fish consumption.
The Ministry of Oceans and Fisheries said on Friday that it made the move because of Tokyo’s uncertain progress on stopping contaminated water from flowing into the ocean and worries about how the clean-up will advance.
“This measure is due to the public’s growing concerns regarding the fact that hundreds of tons of polluted water, coming from the recent accident scene of Fukushima nuclear disaster, is flowing into the sea everyday”, said government spokesman Shin Joong-don on Friday.
The new measure now includes all fishery products from Fukushima and seven other nearby Japanese prefectures.
Japan has acknowledged that contaminated underground water has been flowing into the Pacific Ocean.
From daily The Morning Star in Britain:
Saturday, February 24, 2018
WTO tells South Korea to allow in Japanese nuclear fish
The government said it wanted to protect public health and safety and would maintain its existing regulations on imports of Japanese seafood.
Japan had complained to the WTO about South Korea’s ban, saying it violated WTO rules, was discriminatory and served as a trade barrier.
That tightened restrictions already imposed after the nuclear disaster at the Fukushima Dai-Ichi nuclear power station in March 2011, when a tsunami wrecked the plant and caused its reactors to melt down.
It also required inspection certificates for food products from Japan if small amounts of radioactive cesium or iodine were detected.
China also bans seafood and other agricultural products from Fukushima and nine other prefectures, including Tokyo. It requires certificates on foods from the rest of Japan.