A new study finds that starlet sea anemones have the unique ability to grow more tentacles when they've got more to eat.
- These anemones belong to the Cnidaria phylum that continues developing through its lifespan.
- The starlet sea anemone may grow as many as 24 tentacles, providing there's enough food.
- When deprived of the chance to reproduce, they also grow more tentacles.
Starlet sea anemone basics<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDM5Mzk3MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0Njc2MDk0OX0.q_e2-_VyGcBaOoGM53Uu1XZPaaVxsPhsn7shaxVGu1c/img.jpg?width=980" id="ac056" class="rm-shortcode" data-rm-shortcode-id="200a59225bbce7ddda78d80a20fc267d" data-rm-shortcode-name="rebelmouse-image" alt="sea anemone" />
Credit: Smithsonian Environmental Research Center/Flickr<p>The <a href="https://en.wikipedia.org/wiki/Starlet_sea_anemone" target="_blank">starlet sea anemone</a>, or <em>Nematostella vectensis</em>, lives burrowed into the mud and silt of coastal salt marshes. Research suggests it's originally native to the east coast of North America, although it can also be found along the continent's west coast, around Nova Scotia, and in U.K. coastal marshes.</p><p>Being stationary creatures, starlet sea anemones have to reach out and grab nutrition floating by. Their natural diet is mainly copepods and midge larvae, though they're also perfectly happy eating brine shrimp in a laboratory setting. The anemones grab food with their tentacles whose cilia then wiggle the meal down to their mouths.</p><p>In the larval stage, the anemones have a quartet of tentacles, though they may develop up to 24 of them. A more typical amount is 16.</p><p>While the starlet sea anemone may grow larger in a lab setting, in the wild its clear, worm-like body typically extends from 10 to 19 millimeters (about three quarters of an inch) in length. Tentacles may add another 8 mm.</p><p>Members of the phylum to which the starlet sea anemone belongs, the <a href="https://en.wikipedia.org/wiki/Cnidaria" target="_blank"><em>Cnidaria</em></a> phylum, have the unique ability to grow new body parts throughout their lives in response to environmental influences. Among these influences are fluctuations in the amount of available food. Nonetheless, no other animal has yet been seen growing new appendages when they get extra sustenance.</p>
The study<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDM5NDAwOS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyOTMzMTcyMX0.aSMrGNPw3Hz_dAmy-PGe7sWHp-ePGZFhi4AT2M5zEfE/img.jpg?width=980" id="7f3ff" class="rm-shortcode" data-rm-shortcode-id="fb709c543b60912c99dc5ee9c2871d49" data-rm-shortcode-name="rebelmouse-image" />
Tentacles budding, or not, under different feeding conditions
Credit: Ikmi, et al./Nature Briefing<p>Observations of starlet sea anemones in his lab prompted lead author of the paper, <a href="https://www.embl.de/research/units/dev_biology/ikmi/members/index.php?s_personId=CP-60026325" target="_blank">Aissam Ikmi</a> of the European Molecular Biology Lab Heidelberg, to undertake the new research. He'd noticed what seemed to be an association between the amount of brine shrimp being consumed and the sprouting of new tentacles.</p><p>Ikmi and his team raised over 1,100 starlet sea anemone polyps to which they fed brine shrimp. Some of them began with 4 tentacles while the rest already had 16.</p><p>For over six months, the researchers varied the animals' food supply at cyclical intervals, feeding the anemones for a few days and then stopping for a few days.</p><p>The scientists tracked tentacle growth throughout the experiment, creating a spatio-temporal map that identified periods of tentacle growth in relation to feeding cycles.</p><p>They found that the anemones grew new tentacle pairs during feeding periods, and new tentacle production did indeed stop when their food supply was temporarily cut off. Tentacle-pair budding occurred at the same time as an anemone also doubled its body size.</p><p style="margin-left: 20px;">"When food was available, however, primary polyps grew and sequentially initiated new tentacles in a nutrient-dependent manner, arresting at specific tentacle stages in response to food depletion." — Ikmi, et al.</p>
Two ways to bud<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDM5NDA1NS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYwNjgzNDMzMX0.H7ATzKUDxJvdt1xKiaJe1oKG-foXqPWASin3nNm97gw/img.jpg?width=980" id="abca1" class="rm-shortcode" data-rm-shortcode-id="3ac439c1ad951d3a2aa2afa4b3a8a14b" data-rm-shortcode-name="rebelmouse-image" />
In this illustration from the paper, development from 4 to 12 tentacles is characterized by trans budding. Cis budding is present beginning with 16 tentacles.
Credit: Ikmi, et al./Nature Briefing<p>The team identified two budding modalities, they named "cis" and "trans." In both modes, pairs of tentacles were produced, budding either simultaneously or consecutively. In:</p><ul><li><em>Trans budding</em> — the two new tentacles budded on opposite sides of the anemone.</li><li><em>Cis budding</em> — the two new tentacles budded from within the same segment.</li></ul><div>The experiments also suggest that the starlet sea anemone appears to have ability to make good use of available energy dependent on its situation. Being prevented from spawning, for example, prompted the anemones to grow more tentacles, as if they were rechanneling the energy they'd have otherwise directed to reproduction.</div>
The relatively quick evolution of nine unusual shark species has scientists intrigued.
- Living off Australia and New Guinea are at least nine species of walking sharks.
- Using fins as legs, they prowl coral reefs at low tide.
- The sharks are small, don't be frightened.
Don't mess with success<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjYwMzkxNS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1MDMyOTcyOH0.8IxVi0ssd9VhYYbf7ytjeis1794LxD7QXE_h8h1JWlE/img.jpg?width=980" id="1539e" class="rm-shortcode" data-rm-shortcode-id="4762300cf2aedafae299ef7d032e8810" data-rm-shortcode-name="rebelmouse-image" />
Walking to dinner<div style="padding:56.25% 0 0 0;position:relative;"><iframe src="https://player.vimeo.com/video/385921449" style="position:absolute;top:0;left:0;width:100%;height:100%;" frameborder="0" allow="autoplay; fullscreen" allowfullscreen></iframe></div><script src="https://player.vimeo.com/api/player.js"></script><p>The walking sharks, or "epaulette sharks," live in coastal waters off northern Australia and the island of New Guinea. They prowl coral reefs when the tide goes out, walking through shallow water on their pectoral fins in the front and pelvic fins in the back, on the hunt for crabs, shrimp, small fish. They're adept at wriggling their way into tight nooks to find food, too. "At less than a meter long on average," says <a href="https://researchers.uq.edu.au/researcher/1251" target="_blank">Christine Dudgeon</a> of UQ, "walking sharks present no threat to people, but their ability to withstand low oxygen environments and walk on their fins gives them a remarkable edge over their prey of small crustaceans and mollusks." Says Dudgeon, "During low tides, they became the top predator on the reef."</p><p>The abilities of the small sharks — they're less than three feet in length — definitely put them in a class of their own, says Dudgeon: "These unique features are not shared with their closest relatives the bamboo sharks or more distant relatives in the carpet shark order including wobbegongs and whale sharks."</p><p>Though the five epaulette species don't look much alike, varying in markings and color, their DNA identified them as family. Says Dudgeon, "We estimated the connection between the species based on comparisons between their mitochondrial DNA which is passed down through the maternal lineage. This DNA codes for the mitochondria which are the parts of cells that transform oxygen and nutrients from food into energy for cells."</p>
What's the hurry?<div id="e313b" class="rm-shortcode" data-rm-shortcode-id="PRFA261579893663"><blockquote class="instagram-media" data-instgrm-captioned data-instgrm-version="4" style=" background:#FFF; border:0; border-radius:3px; box-shadow:0 0 1px 0 rgba(0,0,0,0.5),0 1px 10px 0 rgba(0,0,0,0.15); margin: 1px; max-width:658px; padding:0; width:99.375%; width:-webkit-calc(100% - 2px); width:calc(100% - 2px);"> <div style="padding:8px;"> <div style=" background:#F8F8F8; line-height:0; margin-top:40px; padding:50% 0; text-align:center; width:100%;"> <div style=" background:url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACwAAAAsCAMAAAApWqozAAAAGFBMVEUiIiI9PT0eHh4gIB4hIBkcHBwcHBwcHBydr+JQAAAACHRSTlMABA4YHyQsM5jtaMwAAADfSURBVDjL7ZVBEgMhCAQBAf//42xcNbpAqakcM0ftUmFAAIBE81IqBJdS3lS6zs3bIpB9WED3YYXFPmHRfT8sgyrCP1x8uEUxLMzNWElFOYCV6mHWWwMzdPEKHlhLw7NWJqkHc4uIZphavDzA2JPzUDsBZziNae2S6owH8xPmX8G7zzgKEOPUoYHvGz1TBCxMkd3kwNVbU0gKHkx+iZILf77IofhrY1nYFnB/lQPb79drWOyJVa/DAvg9B/rLB4cC+Nqgdz/TvBbBnr6GBReqn/nRmDgaQEej7WhonozjF+Y2I/fZou/qAAAAAElFTkSuQmCC); display:block; height:44px; margin:0 auto -44px; position:relative; top:-22px; width:44px;"> </div></div><p style=" margin:8px 0 0 0; padding:0 4px;"> <a href="https://www.instagram.com/p/B7q3XyIl4ra/" style=" color:#000; font-family:Arial,sans-serif; font-size:14px; font-style:normal; font-weight:normal; line-height:17px; text-decoration:none; word-wrap:break-word;" target="_top">Conservation International on Instagram: “A new paper from @ConservationOrg, @uniofqld, @lipiindonesia, @csirogram and @uflorida, confirms walking sharks are the most recently…”</a></p> </div></blockquote></div><p>The researchers theorize that a few factors may have accelerated the epaulets' evolution. First off, they keep to themselves in their own separate region, with extensive inbreeding perhaps speeding up the rate of mutation. "Data suggests the new species evolved after the sharks moved away from their original population, became genetically isolated in new areas and developed into new species," explains Dudgeon. "They may have moved by swimming or walking on their fins, but it's also possible they 'hitched' a ride on reefs moving westward across the top of New Guinea, about two million years ago."</p><p>Another possible factor are the ever-changing reefs themselves. They're continually in flux as oceans change and as corals live and die, with rising and falling sea levels, as well as changing currents and temperatures. The epaulettes' success depends on adapting quickly to a very dynamic environment, about which Naylor says, "It's the shark equivalent of the Galápagos, where you can see shark evolution in action."</p><p>Beachgoers needn't fear for their tootsies just yet, but just wait another few million years, and who knows?</p>
Climate-driven changes in phytoplankton communities will intensify the blue and green regions of the world’s oceans.
Jennifer Chu | MIT News Office
February 4, 2019
Climate change is causing significant changes to phytoplankton in the world's oceans, and a new MIT study finds that over the coming decades these changes will affect the ocean's color, intensifying its blue regions and its green ones. Satellites should detect these changes in hue, providing early warning of wide-scale changes to marine ecosystems.
It has experts baffled.
- On November 11, seismologists began puzzling over a weird low-frequency rumble that rang the entire planet.
- The wave coming from somewhere was weirdly simple and tied to no known events.
- More comprehensive study of an uncharted area of the ocean floor could provide an explanation of the mystery.
What’s so weird about the mystery rumble?<p>While Mayotte <em>has</em> experienced hundreds of tremors since last May, the strongest, a 5.8 quake, occurred on May 15 and since then they've been tapering off in recent months. And there's been no seismic activity that corresponds to the November wave. Still, the seismology community suspects it's somehow related to the recent activity off Mayotte.</p><p>Normally, earthquakes produce "wave trains" <a href="http://www.geo.mtu.edu/UPSeis/waves.html" target="_blank">comprised of</a> high-frequency P (for "Primary") waves that travel in pulses, as well as mid-frequency S (for "Secondary") waves that wiggle side-to-side. Slow, low-frequency waves such as the mystery rumble are generally produced at the tail end of intense earthquakes, but again, there hasn't been one anywhere in the right time frame that we know of.</p><p>Also, and just as "odd," is that the wave is monochromatic. Most waves contain a cluster of waves at different speeds, or frequencies, that make for a fuzzy, complicated burst of a waveshape on monitoring equipment. The November wave was comprised of just a single frequency, and appeared as an unusually simple, clean zig-zag of about 17 seconds in length. Helen Robinson at the University of Glasgow, mischievously suggests to <em>National Geographic</em>, "They're too nice; they're too perfect to be nature." It could be surrounding rock is filtering out other waves. Supporting this possibility is that, when the lowest frequencies are filtered out of the waveform, noise appears that could be faint P and S signals are seen. Independent seismologist Anthony Lomax <a href="https://twitter.com/ALomaxNet/status/1061637338709790721" target="_blank"><u>tweeted</u></a> the following image.</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xODkzODI4OC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY2MzI4MzM0OH0.PxpgyW7BUNPrM0qqHBAnerreao7hFbmVOrmPiyNzayY/img.jpg?width=980" id="50e7f" class="rm-shortcode" data-rm-shortcode-id="d077d7c0820ee96c2fefdff430b4ac34" data-rm-shortcode-name="rebelmouse-image" />
At the top is the simple, unfiltered mystery wave. The bottom shows possible P- and S-wave echoes when the wave was filtered.