Swiming sea cucumbers, video

This 14 June 2019 video says about itself:

Weird and Wonderful: Swimming sea cucumbers

It can be hard to move from place to place for many animals that live on the seafloor and move slowly. Most sea cucumbers (Holothurians) live a sedentary life on the bottom of the ocean, eating sediment or detritus that rains down from above. But some sea cucumbers leave the life of eating and pooping on the seafloor temporarily by swimming. They may do this as a defense behavior, or to find a mate. Sea cucumbers have made remarkable adaptations to master the challenges of living in the deep sea.

For more information on the importance of holothurians in deep ecosystems see here.


Clownfish and sea anemones, new research

This 2014 video is called Clownfish and Anemones.

From the American Museum of Natural History in the USA:

Finding ‘Nemo’s’ family tree of anemones

New study details evolutionary relationships of clownfish-hosting

June 19, 2019

Summary: A recent study presents a new tree of life for clownfish-hosting sea anemones along with some surprises about their taxonomy and origins.

Thanks in part to the popular film Finding Nemo, clownfishes are well known to the public and well represented in scientific literature. But the same can’t be said for the equally colorful sea anemones — venomous, tentacled animals — that protect clownfishes and that the fish nourish and protect in return. A new study published online this month in the journal Molecular Phylogenetics and Evolution takes a step to change that, presenting a new tree of life for clownfish-hosting sea anemones along with some surprises about their taxonomy and origins.

“It’s astounding that when we look at the relationship between clownfishes and sea anemones, which is perhaps one of the most popular examples of symbiosis out there, we have essentially no clue what is going on with one of the two major players,” said Estefanía Rodríguez, one of the co-authors on the new study and an associate curator in the American Museum of Natural History’s Division of Invertebrate Zoology.

The relationship between the anemone and the clownfish is a mutually beneficial one. The fish have the ability to produce a mucus coating that allows them to shelter within the anemone’s venom-filled tentacles without being stung. This protects clownfishes from bigger fishes, like moray eels, which can be stung by the anemone if they get too close. In return, the highly territorial clownfishes will ward away animals that might try to eat the anemone. In addition, their feces serve as an important source of nitrogen for the anemone, and some research suggests that as the fish wiggle through the anemone’s swaying tentacles, they help oxygenate the host, possibly helping it grow.

There are about 30 clownfishes that have this symbiotic relationship with anemones, and they originated in the “coral triangle” of southeast Asia. There are 10 described species of clownfish-hosting anemones, but scientists suspect that the total number may be much higher. And the information on the origin of these species, as well as the number of times the symbiosis evolved in anemones, is sparse and dated. To fill in these gaps, the research team, led by Museum Gerstner Scholar and Lerner Gray Postdoctoral Fellow Benjamin Titus, built a phylogenetic tree based on DNA from newly collected anemone specimens.

They found that as a group, anemones independently evolved the ability to host clownfish three times throughout history. That finding in itself was not unexpected, but the groupings of the species were very different than what previous work had predicted.

Two of the three independent groups originated in the Tethys Sea, an ancient ocean that separated the supercontinent of Laurasia from Gondwana during much of the Mesozoic, and in today’s geography, is located near the Arabian Peninsula. The data are unclear about the origin of the third group.

“For a symbiosis that’s supposedly highly co-evolved, the groups originated in very different parts of the world and probably also at very different times,” Titus said.

The findings suggest that these anemones, at least the ones that originated in the Tethys, are quite old, living at least 12 to 20 million years ago and possibly earlier.

Research on this group is especially relevant as clownfishes — and their anemones — face threats from the aquarium and pet trade.

“These are very heavily collected animals, but we don’t even know how many species exist in this group,” Rodríguez said. “We have a lot of work to do so we can determine what’s there now, what kind of threats they face, and how we can protect them.”

Other authors include Charlotte Benedict, Auburn University; Robert Laroche, University of Houston; Luciana C. Gusmão, Vanessa Van Deusen, and Tommaso Chiodo, American Museum of Natural History; Christopher P. Meyer, National Museum of Natural History; Michael L. Berumen, King Abdullah University of Science and Technology; Aaron Bartholomew, American University of Sharjah; Kensuke Yanagi, Costal Branch of Natural History Museum and Institute, Japan; James D. Reimer, University of the Ryukyus, Japan; Takuma Fujii, Kagoshima University; and Marymegan Daly, The Ohio State University.

This work was supported in part by the Gerstner Scholars Postdoctoral Fellowship and the Gerstner Family Foundation, the Lerner-Gray Fund for Marine Research, and the Richard Gilder Graduate School at the American Museum of Natural History; the National Science Foundation’s (NSF) Research Experience for Undergraduates program (grant # DBI 1358465); NSF 1457581 and DEB 1257630; the Japan Science and Technology Agency and the Japan International Cooperation Agency in cooperation with Palau International Coral Reef Center and Palau Community College (SATREPS P-CoRIE); Japan Society for the Promotion of Science Kakenhi Grants (JP255440221, JP17K15198, JP17H01913); Kagoshima University; King Abdullah University of Science and Technology Office of Competitive Research Funds (CRG-1-2012-BER-002).

Rare pink grasshopper, photo

Pink grasshopper

This photo, by 1968Tj from the Netherlands, shows a grasshopper which officially should have been green, but is pink.

That colour condition is called erythrism. It occurs rarely, also in, eg, rabbits, snakes, frogs and birds’ eggs.

It is a bit similar to melanism making a ‘grey’ seal a black seal.

Or to a supposedly black blackbird being white or whitish because of albinism or leucism.

Cambrian life explosion, because of volcanoes?

This 2016 video says about itself:

Right at the beginning of the Paleozoic, there was a huge explosion of more complex life. And that’s when things started to get really interesting.

From the University of Exeter in England:

Plate tectonics may have driven ‘Cambrian Explosion’

June 19, 2019

The quest to discover what drove one of the most important evolutionary events in the history of life on Earth has taken a new, fascinating twist.

A team of scientists have given a fresh insight into what may have driven the “Cambrian Explosion” — a period of rapid expansion of different forms of animal life that occurred over 500 million years ago.

While a number of theories have been put forward to explain this landmark period, the most credible is that it was fuelled by a significant rise in oxygen levels which allowed a wide variety of animals to thrive.

The new study suggests that such a rise in oxygen levels was the result of extraordinary changes in global plate tectonics.

During the formation of the supercontinent ‘Gondwana’, there was a major increase in continental arc volcanism — chains of volcanoes often thousands of miles long formed where continental and oceanic tectonic plates collided. This in turn led to increased ‘degassing’ of CO2 from ancient, subducted sedimentary rocks.

This, the team calculated, led to an increase in atmospheric CO2 and warming of the planet, which in turn amplified the weathering of continental rocks, which supplied the nutrient phosphorus to the ocean to drive photosynthesis and oxygen production.

The study was led by Josh Williams, who began the research as an MSc student at the University of Exeter and is now studying for a PhD at the University of Edinburgh.

During his MSc project he used a sophisticated biogeochemical model to make the first quantification of changes in atmospheric oxygen levels just prior to this explosion of life.

Co-author and project supervisor Professor Tim Lenton, from the University of Exeter’s Global Systems Institute said: “One of the great dilemmas originally recognised by Darwin is why complex life, in the form of fossil animals, appeared so abruptly in what is now known as the Cambrian explosion.

“Many studies have suggested this was linked to a rise in oxygen levels — but without a clear cause for such a rise, or any attempt to quantify it.”

Not only did the model predict a marked rise in oxygen levels due to changes in plate tectonic activity, but that rise in oxygen — to about a quarter of the level in today’s atmosphere — crossed the critical levels estimated to be needed by the animals seen in the Cambrian explosion.

Williams added: “What is particularly compelling about this research is that not only does the model predict a rise in oxygen to levels estimated to be necessary to support the large, mobile, predatory animal life of the Cambrian, but the model predictions also show strong agreement with existing geochemical evidence.”

“It is remarkable to think that our oldest animal ancestors — and therefore all of us — may owe our existence, in part, to an unusual episode of plate tectonics over half a billion years ago” said Professor Lenton.

Egg-sucking sea slug discovery in Florida, USA

This 2012 video is about Sacoglossa, mostly vegetarian relatives of the recently discovered species.

From the Florida Museum of Natural History in the USA:

Egg-sucking sea slug from Florida’s Cedar Key named after Muppets creator Jim Henson

June 18, 2019

Feet from the raw bars and sherbet-colored condominiums of Florida’s Cedar Key, researchers discovered a new species of egg-sucking sea slug, a rare outlier in a group famous for being ultra-vegetarians.

Named Olea hensoni in honor of Muppets creator Jim Henson, the slug belongs to the sacoglossans, a group of more than 300 species that are such enthusiastic eaters of plants that many of them turn green and some resemble leaves. A few species, nicknamed “solar-powered slugs“, have even developed the ability to keep algae alive inside their bodies to photosynthesize their food for them, becoming a fusion of plant and animal.

But O. hensoni has gone rogue, joining two other sacoglossan species — Olea hansineensis from the northeast Pacific and Calliopaea bellula in the Mediterranean — that abandoned a diet of seaweed to prey on the eggs of their fellow slugs and snails.

“In the middle of this group of super-herbivores, there are a couple of species that have rebelled in ‘The Hills Have Eyes‘ kind of way and have gone almost full-blown cannibal,” said Patrick Krug, professor of biological sciences at California State University. “These are like the Venus fly traps of the slug world. They’ve switched from being harmless, friendly creatures to predators.”

In 2017, Cedar Key’s waterfront still bore wreckage from Hurricane Hermine when Gustav Paulay, Florida Museum curator of invertebrate zoology, slipped on divers boots and walked onto a sand flat exposed by the low tide. He was scouting for nudibranchs, worms, sea snails and crabs to show his students. Picking up a Jell-O-like egg mass, he spotted a sea slug about the size of a grain of rice inside.

“I assumed it was a well-known species,” he said. “I know its relative from the northeast Pacific quite well, so I figured, ‘Okay, good, we got an Olea’ and put it in the bag.”

It wasn’t until he contacted Krug, a sacoglossan expert, that he realized how unique the slug was.

“I sent it to Pat, and he was like, ‘Oh my God! You got something weird that’s not known from the western Atlantic,'” Paulay said. “What I found interesting was that this was the third example in the world of this feeding mode in this lineage of animals. I thought there were a lot more of them. I was tickled that we got one in Florida.”

Krug said finding an egg-sucking slug in the Gulf of Mexico was “crazy.”

“It was really surprising that a member of this group would show up in the waters around Florida because the other two species are from cold, northern waters”, he said.

Even odder, O. hensoni is far more closely related to the Pacific egg-sucking slug than the Mediterranean one.

“That makes no sense at all,” Krug said. “But that’s what the DNA and the anatomy tell us. It’s just a relic of a very old lineage that presumably got trapped in the Caribbean a long time ago and became isolated from its Pacific relatives.”

Paulay said O. hensoni is a prime example of how much marine life remains to be discovered, even in the aquatic equivalent of a backyard.

“Cedar Key is a well-studied area, and it’s still yielding new species,” he said. “You don’t need a scuba tank to find them. You just need to walk out in your flip-flops and look under your feet.”

Although O. hensoni is only the third documented species of egg-eating slug, Paulay recalled seeing other slugs preying on egg masses during his fieldwork in the Indo-Pacific.

“They’re probably in quite a few places, but nobody has ever looked,” he said. “One of the things I’m pretty bummed about is I’ve seen sucking slugs elsewhere, but I’ve never bothered to go after them.”

The researchers are not sure when the slugs made the plant-to-egg dietary switch or why, but speculate that egg capsules offer a nutritious and largely untapped food resource. Slugs and snails protect their eggs by encasing them by the thousands inside a mucous ball, an effective barrier against many would-be predators. But egg-sucking slugs have successfully developed a way to bulldoze their way inside, Krug said.

“Unlike the switchblade-like tooth of its plant-eating relatives, Olea has a tooth nubbin, which it can punch into jelly-like egg masses to suck out the eggs or embryos like someone sucking up boba from bubble tea,” he said.

Like other sea slugs, O. hensoni is hermaphroditic, having both male and female reproductive parts. Because genitalia can be useful for identifying slug species, the researchers coated the slug’s penis with gold and imaged it with a scanning electron microscope. Krug and Paulay did not observe O. hensoni reproducing in the lab, but the needle-like shape of its male genitalia may indicate that it engages in the “penis fencing” reproductive behavior seen in some sacoglossans and flatworms.

“It’s pretty extreme as penial stylets go, so it looks like it’s used for hypodermic insemination or for anchoring inside a sperm receptacle organ,” Krug said. “It’s a lot bigger than a lot of stylets I see in species that engage in some pretty dramatic fencing behaviors.”

Naming the slug after Jim Henson was an idea that came to Krug as he was thinking about O. hensoni’s creamy brown to yellow coloring — a standout in a group that is iconically green.

“It made me think of Kermit the Frog’s song ‘It’s not Easy Being Green'”, he said. “That made me laugh because I remember being a kid, eating eggs for breakfast and watching ‘Sesame Street.'”

As far as Krug knows, this is the first animal named after Henson.

“Jim Henson was one of those people who created things that were educational, positive and impactful and made the world a better place. That’s something that should be honored.”

Hilton de Castro Galvão Filho, who began the research in Krug’s lab and is now at the University of São Paulo, is the study’s lead author.