Exceptionally high-quality videos allow scientists to formally introduce a remarkable new comb jelly.
- Gorgeous simplicity characterizes the comb jelly recently discovered by National Oceanic and Atmospheric Administration Fisheries.
- The small denizen of the deep was spotted three times beneath the waters off Puerto Rico.
- Though it's unusual to formally identify an animal strictly based on video observations, the quality of NOAA's video made it possible in a case where there's no better alternative.
Meet cute beneath the waves<p>The first encounter humanity had with the jelly<em> </em>occurred on April 10, 2015, when Deep Discoverer (a remotely operated vehicle or ROV) came across the gelatinous wonder. Fortunately, the ROV sports cameras that were sufficiently high-definition to clearly capture <em>Duobrachium sparksae's</em> fine details.</p><p>The animal was first noticed in a video feed by Mike Ford of the shoreside science team working in NOAA's Exploration Command Center far away, outside of Washington, D.C. The ROV was working the Arecibo amphitheater canyon. What Ford saw was, in his words, "a beautiful and unique organism."</p><p>Deep Discoverer's cameras produce externally high-resolution images, and are capable of measuring objects as small as a millimeter.The comb jelly's body is about 6 centimeters in size, and its tentacles are about 30 cm long.</p><p>While video-based animal identification can be controversial, there was little choice in this case. "We didn't have sample collection capabilities on the ROV at the time," says Collins. "Even if we had the equipment, there would have been very little time to process the animal because gelatinous animals don't preserve very well; ctenophores are even worse than jellyfish in this regard."</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDg0ODEwNy9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY2NjA0MjMxMH0.X3YXqsUtddtArtXOz7z5w-Zli0Z2vCE1UoSRLU63898/img.jpg?width=980" id="fffe5" class="rm-shortcode" data-rm-shortcode-id="5b42f13f528c33eeaeb512320cac7f23" data-rm-shortcode-name="rebelmouse-image" data-width="1232" data-height="1440" />
Credit: Nicholas Bezio/NOAA Office of Ocean Exploration and Research
Describing Duobrachium sparksae<p>All told, three individuals were observed by the scientists in three separate encounters with the ROV. The image at the top of this article is from the second encounter. The fact that three separate examples were easily spotted leaves scientists hopeful that the creature is not a rarity in the seas.</p><p>Ford describes what they saw:</p><p style="margin-left: 20px;">"The ctenophore has long tentacles, and we observed some interesting movement. It moved like a hot air balloon attached to the seafloor on two lines, maintaining a specific altitude above the seafloor. Whether it's attached to the seabed, we're not sure. We did not observe direct attachment during the dive, but it seems like the organism touches the seafloor."</p><p>The role that <em>Duobrachium sparksae</em> plays in its ecosystem is not yet understood.</p><span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="83f6005db2fc4b5e7ec6fc207ff70639"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/o0nkwCKpaRA?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
Finding a place in the family<p>The manner in which light refracted prismatically off the jelly's cilia combs immediately placed it in the ctenophore family as a start.</p><p>Collins explains, "We don't have the same microscopes as we would in a lab, but the video can give us enough information to understand the morphology in detail, such as the location of their reproductive parts and other aspects."</p><p>"We went," says Ford, "through the historical knowledge of ctenophores and it seemed clear this was a new species and genus as well. We then worked to place it in the tree of life properly."</p><p>The videos—the only "specimens" there are of <em>Duobrachium sparksae</em>—are now publicly accessible as part of the Smithsonian National Museum of Natural History Collection.</p>
The microbes that eventually produced the planet's oxygen had to breathe something, after all.
- We owe the Earth's oxygen to ancient microbes that photosynthesized and released it into the world's oceans.
- A long-standing question has been: Before oxygen, what did they breathe?
- The discovery of microbes living in a hostile early-Earth-like environment may provide the answer.
Unassuming but remarkable microbial mats<p> Photosynthesis chiefly requires sunlight, water, and CO<sup>2</sup>. The CO<sup>2</sup> gets broken down into carbon and oxygen — the plant uses some of this oxygen and releases the rest. Without oxygen molecules, though, how did this work? </p><p> There are known microbial mats today that live in oxygen-free environments, but they're not thought to be sufficiently like their ancestors to explain ancient photosynthesis in an oxygen-free environment. </p><p> There have been a few oxygen stand-ins proposed. Photosynthesis can work with iron molecules, but fossil-record evidence doesn't support that idea. Hydrogen and sulphur have also been proposed, though evidence for them is also lacking. </p><p> The spotlight began to shift to arsenic in the first decade of the millennium when arsenic-breathing microbial mats were discovered in two hypersaline California lakes, <a href="https://science.sciencemag.org/content/308/5726/1305.abstract" target="_blank">Searles Lake</a> and <a href="https://www.discovermagazine.com/planet-earth/mono-lake-bacteria-build-their-dna-using-arsenic-and-no-this-isnt-about-aliens" target="_blank" rel="noopener noreferrer">Mono Lake</a>. In 2014, Visscher and colleagues <a href="https://www.nature.com/articles/ngeo2276" target="_blank">unearthed indications</a> of arsenic-based photosynthesis, or "arsenotrophic," microbial mats deep in the fossil record of the Tumbiana Formation of Western Australia. </p><p> Still, given the ever-shifting geology of the planets, the fractured ancient fossil record makes definitive study of ancient arsenotrophic photosynthesis difficult. The fossil record can't identify the role of the arsenic it reveals: was it involved in photosynthesis or just a toxic chemical that happened to be there? </p><p>Then, last year, arsenic-breathing microorganisms <a href="https://www.washington.edu/news/2019/05/01/arsenic-breathing-life-discovered-in-the-tropical-pacific-ocean/" target="_blank" rel="noopener noreferrer">were discovered</a> in the Pacific Ocean. A sulphur bacterium, <em>Ectothiorhodospira sp.</em> was also recently found to be metabolizing arsenic into <a href="https://en.wikipedia.org/wiki/Arsenite" target="_blank">arsenite</a> in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5064118/" target="_blank" rel="noopener noreferrer">Big Soda Lake</a> in Nevada. </p>
An ancient Earth environment, today<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDQ0NzIxMC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1OTQwOTYyN30.v96ZRXpIAf4yzDwcvXzVV3Fa4qULtUMxanXguPHD2wI/img.jpg?width=980" id="9eec4" class="rm-shortcode" data-rm-shortcode-id="a23585c057ee50ed500b96125e4a6b05" data-rm-shortcode-name="rebelmouse-image" data-width="2873" data-height="1640" />
a Map of Northern Chile; b Detail of frame showing Laguna La Brava in the southern Atacama; c The channel showing the mats in purple; d Hand sample, cross-section; e Microscopic image of bacteria.
Credit: Visscher, et al./Communications Earth & Environment<p>The study reports on Visscher's discovery of a living microbial mat thriving in an arsenic environment in Laguna La Brava in the Atacama Desert in Chile. "We started working in Chile," Visscher tells <a href="https://today.uconn.edu/2020/09/without-oxygen-earths-early-microbes-relied-arsenic-sustain-life/" target="_blank"><em>UConn Today</em></a>, "where I found a blood-red river. The red sediments are made up by <a href="https://en.wikipedia.org/wiki/Anoxygenic_photosynthesis" target="_blank">anoxogenic</a> photosynthetic bacteria. The water is very high in arsenic as well. The water that flows over the mats contains hydrogen sulfide that is volcanic in origin and it flows very rapidly over these mats. There is absolutely no oxygen."</p><p>The mats had not previously been studied, and the conditions in which they live are tantalizingly similar to those of early Earth. It's a high-altitude, permanently oxygen-free state with extreme temperature swings and lots of UV exposure. </p><p>The mats that somewhat resemble Nevada's purple <em>Ectothiorhodospira sp.</em> are going about their business of making carbonate deposits, forming new stromatolites. Most excitingly, those deposits contain evidence that the mats are metabolizing arsenic. The rushing waters surrounding the mats are also rich in hydrogen sulphide and arsenic.</p><p>Says Visscher, "I have been working with microbial mats for about 35 years or so. This is the only system on Earth where I could find a microbial mat that worked absolutely in the absence of oxygen."</p><p>Not that Earth is the only place where this could happen. Visscher notes that the equipment they used for studying the Laguna La Brava mats is not unlike the system aboard the Mars Perseverance Rover. "In looking for evidence of life on Mars, they will be looking at iron, and probably they should be looking at arsenic also."</p>
Sharks fear killer whales. How does this impact the ecosystems they share?
- A new study finds that sharks will flee areas they met orcas in for up to a year.
- Killer whales are known to eat sharks, but it is unknown if the sharks are fleeing because they know that too.
- The discovery will change our understanding of how marine ecosystems evolve.
The true apex predator<p>The study, titled "Killer whales redistribute white shark foraging pressure on seals," results from years of investigations into the movements and behavior of 165 tagged great white sharks, observations and records of killer whale movements, and information on seal populations off the coast of California. They also looked to previous descriptions of shark and whale interactions to give context to their findings.</p><p>The sharks immediately turned tail and fled in every time they crossed paths with orcas. They'd also stay away from that place long afterward. Only <em>one </em>observed shark dared venture back to where it had just encountered the whales, and it didn't stick around. Most of the sharks merely fled a bit further up the coastline, while others went much further out to sea to avoid the whales. </p>
Why are they doing this?<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="14ccb270e8cc6888b69118539a29b63b"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/B7GHCJXwLw8?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>Orcas have been known to eat great whites. The remains of the sharks are a grotesque sight to behold and are always missing their <a href="https://www.nationalgeographic.com/animals/2019/07/killer-whales-orcas-eat-great-white-sharks/#:~:text=By%20Emma%20Rigney&text=In%20October%201997%2C%20tourists%20in,killer%20whales%20eating%20white%20sharks." target="_blank">livers</a>, no matter how much else remains or is missing. If the orcas have discovered a source of Chianti to pair with them or not remains unknown at this <a href="https://youtu.be/bHoqL7DFevc?t=28" target="_blank">time</a>.</p><p>However, we don't currently know if the sharks are fleeing because they understand that risk, because they knew the orcas would fight them for the same food supply, because whales look big and scary to them, or some combination of the three.</p><p>Before this gets too frightening, there are no known cases of wild orcas killing <a href="https://en.wikipedia.org/wiki/Killer_whale_attack" target="_blank">humans</a>, and only a few examples of injuries being caused by these interactions. <a href="https://bigthink.com/surprising-science/orcas-and-stress" target="_blank">Orcas kept in tiny boxes</a> for long periods can be a bit more violent, but that's another story. </p>
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" data-width="1440" data-height="1422" />
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" data-width="1440" data-height="595" />
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.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDM5NDA1NS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY2OTkwNjMzMX0.VN5Q8MFO7QnQRiBTVY4xg_hqMN-VvqBqDBLlNCb1mL0/img.jpg?width=980" id="5aff3" class="rm-shortcode" data-rm-shortcode-id="3ac439c1ad951d3a2aa2afa4b3a8a14b" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="470" />
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>
A new study bases its calculations on more than the great white shark.
- Previous estimates of the megalodon's size were based solely on its teeth compared to the star of "Jaws."
- The prehistoric monster is as closely related to other sharks.
- Imagine just a dorsal fin as tall as you are.
What’s different about this analysis<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzg3MjU5OS9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTYxNDc2MTQyNn0.K38h9qHeCM7jtYLA2Z25W7ZC9NiekmvL6CkQy82szzU/img.png?width=980" id="24ad8" class="rm-shortcode" data-rm-shortcode-id="fbc76e6dc6f82d299c7828a80272eede" data-rm-shortcode-name="rebelmouse-image" alt="megalodon compared to a school bus" data-width="1245" data-height="701" />
The megalodon’s revised measurements<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzg0OTAwMy9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzNTM4MjA4M30.uArVFW_ithOZuZ1_oTKCg0y1-2Zue2VRD_C_j2KJVk4/img.jpg?width=980" id="98366" class="rm-shortcode" data-rm-shortcode-id="8caf88dda090ba04f0aac156e15b7a27" data-rm-shortcode-name="rebelmouse-image" alt="shark and diver illustration" data-width="733" data-height="462" />
Credit: Reconstruction by Oliver E. Demuth/Scientific Reports<p>The study proposes the following approximate measurements for a full-grown megalodon:</p><ul><li>Length: about 16 meters (52.5 feet). A full-size school bus is just 45 feet long</li><li>Head size: about 4.65 meters long (15.3 feet) </li><li>Dorsal fin: about 1.62 meters tall (5.3 feet). A person could stand on the back of a megalodon and be about as tall as the fin.</li><li>Tail fin: about 3.85 meters high (12.6 feet) </li></ul><p>Let's just hope this sucker is really extinct. </p>