2020. 2. 17. 18:34ㆍ카테고리 없음
Because I'll never grow tired of seeing incredible footage of sea creatures, here are a few of the best ones I've seen lately.First up, a video by a group called, which is an art-science project led by James Cook University-educated marine biologist Colin Foord, and American musician Jared McKay. 'With the aquarium as our primary medium, we explore the artistic possibilities of living coral reef organisms via HD videography and site-specific artworks,' Foord and McKay say on, which features videos of anemone birth, a coral nursery and the tiny heart urchin pea crab.
The video below, which was a special installment of their Natural History film series last year, celebrates the gorgeous, loopy tendrils of the Portuguese man-o-war ( Physalia physalis) that tumble like curled ribbons from an obscured, gas-filled bladder.from on.Unlike jellyfish, the Portuguese man-o-war is not a single organism, but a colony of four different kinds of smaller animals, called polyps and medusae, that have highly specialised body types to allow for very different functions. The gas-filled bladder, otherwise known as the pneumatophore or sail, is one, and its function is to keep the colony together. Then there's the dactylozooids, or tentacles, which are responsible for finding and capturing food using cnidocytes, or stinging cells. The gastrozooids are the feeding and digesting organisms, while the gonozooids are in charge of producing gametes for reproduction.The first recorded human death by man-o-war occurred in 1987, when a 67-year-old woman was swimming at Riviera Beach in Florida.
Before this, researchers had thought that as much as 15 m of tentacular contact was needed to kill a human, but the team reporting on the death in estimated from the woman's sting marks that she had only touched between 3 and 6 metres-worth of tentacles. At the time of reporting, a young boy had died in Australian waters having been exposed to just 1.5 m of tentacles. The researchers suggested that despite the fact that the victims only had stings on relatively small areas of their bodies, both deaths occured at a time of year when man-o-wars reach full maturity, so these indivisuals were likely at their most robust and venomous.from on.Rumoured to be the inspiration for, Phronima sedentaria is a tiny and translucent deep-sea predator that feeds off gelatinous animals and lives inside their corpses.
Found all over the world in temperate, subtropical and tropical waters, the female Phronima can grow up to 42 mm long, while the males only reach around 15 mm long.The females will capture prey such as siphonophores (a group that includes corals and jellyfish) and barrel-shaped, planktonic tunicates called salps and cut into them using their sharp claws. According to a published in Journal of Crustacean Biology by Carol E. Diebe from the Museum of New Zealand Te Papa Tongarewa, one particular female she observed, 'entered the salp, cut out the brain and gill bar, and consumed them, ate the stomach and its contents, and then remained relatively quiescent for approximately five hours. The female then resumed eating the salp, cutting off strips of tissue at both ends, and removing pieces of the internal organs, eating only the muscle bands'.At this point, she will continue manipulating the gelatinous remains of the salp into a barrel shape by scraping the walls smooth over many hours.
Once the barrel is complete, the female will use her new gelatinous home to propel herself through the ocean in search of more food. She will lay her eggs inside the barrel, and raise and feed her progeny there until they're old enough to leave. Rather fittingly, the Greek origin of the word 'Phronima' means 'clever'from on.Another of the Coral Morphologic videos, this one shows the super-strange lettuce sea slug ( Elysia crispata), which performs a process known as kleptoplasty to stay alive. This involves eating the cell sap of algae, and instead of digesting all of it, will funnel some of it, including the chloroplasts that algae use to conduct photosynthesis, through specialised passages in the digestive tract. They are then stored in appendages called parapodia, and here they will remain for up to four months and undergo photosynthesis to provide the sea slug with extra energy at times when food is scarce.And finally, the real-life Pokemons, Glaucus atlanticus and Glaucus marginatus, commonly known as blue dragons. With very few relatives to speak of, these sea slugs are the only two species that belong the family Glaucidae. They mostly float upside-down on the surface of the ocean, sucking in air and storing it in their stomachs for bouyancy.
Unlikely predators of the Portuguese man-o-war, blue dragons are immune to its toxins, and this allows them to eat everything, including the tentacles. They can then store the toxins in sacs on their cerata, which are those finger-like projections, so they can inflict nasty stings to their own would-be predators later on.The main differences between these two species are that G. Marginata has more cerata than G. Atlanticus, but G. Atlanticus has a much longer tail, or metapodium. And growing to 3 cm in length, G altanticus is much larger than G. Marginata, which only stretches up to 12 mm in length.Pre-order my new book, Zombie Tits, Astronaut Fish and Other Weird Animals (due for release next month),The views expressed are those of the author(s) and are not necessarily those of Scientific American.
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Lewis addresses the sudden increase of jellies to our shores this past year.Many people would have noticed that this summer has been particularly bad with the frequent influxes of Pelagia noctiluca, the mauve stinger, and numbers reaching plague proportions. Cast your mind a little further back to Easter time and there were swarms of Physalia physalis, the Portuguese man o’ war, and other siphonophores littering the beaches. Whilst it is true that we have always suffered the effects of jellyfish blooms over the course of the year, it is also true that 2018 has been one of the worst years for a long time in Gibraltar. Why?The first thing to note is that this is a global phenomenon which is indicative of our changing oceans.
Warmer waters, driven by climate changes, do in fact favour jellyfish reproduction. This is partially due to an increase in food availability because of longer summer seasons which increase the chances of young Mauve stingers reaching adulthood. Already here things can begin to get a little complicated.Plankton are made up of two groups; phytoplankton are the plants and zooplankton, which include the larval stages of most of the coastal species on our coastline. As jellyfish numbers increase then the amount of plankton being consumed also increase and consequently plankton abundance decline; here lies the rub.
Psysalia Psysalis Psyche Rar
The zooplankton will include many species that once out of their planktonic stage actually eat jellyfish and hence the suppression of zooplankton numbers is not a great outcome. All things should be taken with a pinch of salt, after all, a healthy ecosystem should be in balance. Typically, this is the case but climate changes are indeed tipping this delicate balance in favour of the jellies.
Warmer, more acidic waters and lower dissolved oxygen levels, all associated with climate change, are bad for most marine animals, but favour jellyfish.But jellyfish have their predators too. Turtles, tuna, swordfish, salmon, triggerfish and sunfish are all consumers of them, so why are the consumers’ respective numbers not increasing in line with the rise of jellyfish?In the case of tuna, swordfish and salmon, the answer is glaringly obvious, as at one point or another they have ended up on our plate; overfishing. Industrialised commercial fishing techniques have been incredibly efficient at outsmarting these animals and the availability of them at restaurants throughout the year is alarming. Perhaps limiting such destructive fishing practices throughout the Mediterranean would be beneficial, but it would clearly require co-operation from many different Governments.
In truth, there is probably no real will to establish and co-ordinate such an agreement anyways as different countries have opposing vested interests.The three Mediterranean turtles are the loggerhead ( Caretta caretta), the green ( Chelonia mydas) and the leatherback ( Dermochelys coriacea) – and they all eat jellyfish! In the case of the loggerhead and the green, they tend to eat jellies whilst they are hatchlings and juveniles but tend to consume less in adulthood. By contrast, the leatherback eats jellyfish constantly throughout its life. All three species are very important with respect to controlling jellyfish numbers and recent declines in their populations are a worrying trend with all three species presently classified as vulnerable or endangered. Within the Mediterranean, one can find green and leatherback nesting sites in the eastern basin around Greece and Cypress. The leatherback has no known nesting sites within the Med and the closest breeding spots are along the coast of the North West Atlantic. As ocean dwellers they do often visit the Mediterranean searching for food, of which recently, there has been an abundance of.These three species have been affected greatly by plastic pollution as they often mistake plastic bags for jellyfish.
On attempting to ingest the bag they can suffocate on it and this often happens with the greens and the loggerheads whilst they are sub-adults, taking them out of the food web early. Consequently, the predation pressures commonly exerted on jellyfish are removed allowing the plague populations to grow.Unfortunately, there is a similar story with the Grey Trigger fish (Balistes capriscus) and the Sunfish (Mola mola) whose populations are similarly affected by plastic ingestion.A final point to consider, which has been underrepresented in all discussions on this topic, is the effect of the North Atlantic Oscillation (NAO). Briefly, there is a permeant low pressure system over Iceland and a high-pressure system over the Azores. The interaction and relative positions of these systems control the strength of the westerly winds into Europe. In a positive NAO, the Azores high pushes the Atlantic storms towards Northern Europe where it dumps all the rain and keeps the South relatively dry. Inversely then, in a negative NAO year the Azores high pressure system is weaker and so the Atlantic storms hit Southern Europe, making it a wetter winter in Gibraltar but a dryer one in Northern Europe.Some scientific studies have suggested that in the years where we suffer a Negative NAO, like 2018 has been, the subsequent summer suffers more heavily with jellyfish. An interesting observation indeed but worrying should it turn out to be correct as we are likely to see a repetition every 2nd summer.
So, in the spirit of scientific investigation I would propose the following prediction: If the science is correct then summer 2019 should be a positive NAO which should mean a dryer, storm free winter and should also see less jellyfish in the summer time. Here is to hoping it turns out to be correct, or the reaction from the public could be more stinging than the jellyfish!