Horseshoe crab eyes, 400 million years old


This July 2018 video is called What If The Jaekelopterus rhenaniae Didn’t Go Extinct?

From the University of Cologne in Germany:

Compound eyes: The visual apparatus of today’s horseshoe crabs goes back 400 million years

December 3, 2019

The eyes of the extinct sea scorpion Jaekelopterus rhenaniae have the same structure as the eyes of modern horseshoe crabs (Limulidae). The compound eyes of the giant predator exhibited lens cylinders and concentrically organized sensory cells enclosing the end of a highly specialized cell. This is the result of research Dr Brigitte Schoenemann, professor of zoology at the Institute of Biology Didactics at the University of Cologne, conducted with an electron microscope. Cooperation partners in the project were Dr Markus Poschmann from the Directorate General of Cultural Heritage RLP, Directorate of Regional Archaeology/Earth History and Professor Euan N.K. Clarkson from the University of Edinburgh. The results of the study ‘Insights into the 400 million-year-old eyes of giant sea scorpions (Eurypterida) suggest the structure of Palaeozoic compound eyes’ have been published in the journal Scientific Reports — Nature.

The eyes of modern horseshoe crabs consist of compounds, so-called ommatidia. Unlike, for example, insects that have compound eyes with a simple lens, the ommatidia of horseshoe crabs are equipped with a lens cylinder that continuously refracts light and transmits it to the sensory cells.

These sensory cells are grouped in the form of a rosette around a central light conductor, the rhabdom, which is part of the sensory cells and converts light signals into nerve signals to transmit them to the central nervous system. At the centre of this ‘light transmitter’ in horseshoe crabs is a highly specialized cell end, which can connect the signals of neighbouring compounds in such a way that the crab perceives contours more clearly. This can be particularly useful in conditions of low visibility under water. In the cross-section of the ommatidium, it is possible to identify the end of this specialized cell as a bright point in the centre of the rhabdom.

Brigitte Schoenemann used electron microscopes to examine fossil Jaekelopterus rhenaniae specimens to find out whether the compound eyes of the giant scorpion and the related horseshoe crabs are similar or whether they are more similar to insect or crustacean eyes. She found the same structures as in horseshoe crabs. Lens cylinders, sensory cells and even the highly specialized cells were clearly discernible.

‘This bright spot belongs to a special cell that only occurs in horseshoe crabs today, but apparently already existed in eurypterida,’ explained Schoenemann. ‘The structures of the systems are identical. It follows that very probably this sort of contrast enhancement already evolved more than 400 million years ago,’ she added. Jaekelopterus most likely hunted placoderm[i fish]. Here, its visual apparatus was clearly an advantage in the murky seawater.

Sea scorpions, which first appeared 470 million years ago, died out about 250 million years ago, at the end of the Permian age — along with about 95 percent of all marine life. Some specimens were large oceanic predators, such as Jaekelopterus rhenaniae. It reached a length of 2.5 meters and belonged to the family of eurypterida, the extinct relatives of the horseshoe crab. Eurypterida are arthropods, which belong to the subphylum Chelicerata, and are therefore related to spiders and scorpions.

Among the arthropods there are two large groups: mandibulates (crustaceans, insects, trilobites) and chelicerates (arachnid animals such as sea scorpions). In recent years, Schoenemann has been able to clarify the eye structures of various trilobite species and to make decisive contributions to research into the evolution of the compound eye. ‘Until recently, scientists thought that soft tissues do not fossilize. Hence these parts of specimens were not examined until not so long ago’, she concluded.

The new findings on the eye of the sea scorpion are important for the evolution of the compound eyes not only of chelicerates, but also for determining the position of sea scorpions in the pedigree of these animals and for the comparison with the eyes of the related group of mandibulates.

Ancient Puerto Ricans barbecued clams


This 6 September 2015 video says about itself:

Puerto Rican recipe: Stew Clams w/ Pasta

Recipe

12 little clams
12 large clams
1/2 cup olive oil
2 cups of tomato sauce
1 teaspoon Adobo
1 sazon packed
2 tablespoons sofrito
1 tablespoon garlic
2 tablespoons tomato paste
2 bay leaves.

Topped with fresh cilantro and lemon wedges.

And, a long time before 2015 … from Cardiff University in Wales:

Barbequed clams on the menu for ancient Puerto Ricans

Analysis of fossilized shells reveals cooking habits of Caribbean civilizations over 2500 years ago

November 27, 2019

Scientists have reconstructed the cooking techniques of the early inhabitants of Puerto Rico by analysing the remains of clams.

Led by Philip Staudigel, who conducted the analysis as a graduate student at the University of Miami Rosenstiel School and is now a postdoctoral researcher at Cardiff University, the team has used new chemical analysis techniques to identify the exact cooking temperatures at which clams were cooked over 2500 years ago.

With cooking temperatures getting up to around 200oC according to the new analysis, the team believe the early Puerto Ricans were partial to a barbeque rather than boiling their food as a soup.

The study, which also involved academics from the University of Miami and Valencia College, has been published today in the journal Science Advances.

Whilst the results throw new light on the cultural practices of the first communities to arrive on the island of Puerto Rico, they also provide at least circumstantial evidence that ceramic pottery technology was not widespread during this period of history — it’s likely that this would be the only way in which the clams could have been boiled.

Lead author of the study Dr Philip Staudigel, currently at Cardiff University’s School of Earth and Ocean Sciences, said: “Much of peoples’ identity draws upon on where they came from, one of the most profound expressions of this is in cooking. We learn to cook from our parents, who learned from their parents.

“In many parts of the world, written records extend back thousands of years, which often includes recipes. This is not the case in the Caribbean, as there were no written texts, except for petroglyphs. By learning more about how ancient Puerto Rican natives cooked their meals, we can relate to these long-gone peoples through their food.”

In their study, the team analysed over 20kg of fossilised clamshells at the University of Miami’s Rosenstiel School of Marine and Atmospheric Sciences Stable Isotope Lab, which were collected from an archaeological site in Cabo Rojo, Puerto Rico.

The pre-Arawak population of Puerto Rico were the first inhabitants of the island, arriving sometime before 3000 BC, and came from Central and/or South America. They existed primarily from fishing, hunting, and gathering near the mangrove swamps and coastal areas where they had settled.

The fossilised shells, dating back to around 700 BC, were cleaned and turned into a powder, which was then analysed to determine its mineralogy, as well as the abundance of specific chemical bonds in the sample.

When certain minerals are heated, the bonds between atoms in the mineral can rearrange themselves, which can then be measured in the lab. The amount of rearrangement is proportional to the temperature the mineral is heated.

This technique, known as clumped isotope geochemistry, is often used to determine the temperature an organism formed at but in this instance was used to reconstruct the temperature at which the clams were cooked.

The abundance of bonds in the powdered fossils was then compared to clams which were cooked at known temperatures, as well as uncooked modern clams collected from a nearby beach.

Results showed that that the majority of clams were heated to temperatures greater than 100°C — the boiling point of water — but no greater than 200°C. The results also revealed a disparity between the cooking temperature of different clams, which the researchers believe could be associated with a grilling technique in which the clams are heated from below, meaning the ones at the bottom were heated more than the ones at the top.

“The clams from the archaeological site appeared to be most similar to clams which had been barbequed,” continued Dr Staudigel.

“Ancient Puerto Ricans didn’t use cookbooks, at least none that lasted to the present day. The only way we have of knowing how our ancestors cooked is to study what they left behind. Here, we demonstrated that a relatively new technique can be used to learn what temperature they cooked at, which is one important detail of the cooking process.”

Indonesian coral reefs video


This 12 November 2019 video says about itself:

Indonesia’s Coral Reefs

In the second installment of National Geographic’s “Into Water” 360 series, dive into the crystal clear waters of Indonesia with marine social ecologist and National Geographic Explorer Shannon Switzer Swanson. More than a quarter of the world’s aquarium fish population comes from Indonesia. Shannon works with local communities, documenting fishing practices. She is hoping to learn why some fishing families have developed sustainable practices while others have not. “Into Water: Indonesia” is the second stop on an around the world 360 tour that documents the work of female Explorers who’ve dedicated their careers to water-related issues.

American slipper limpet innocent in oyster deaths


This July 2017 video from the USA says about itself:

Meet the scientist working on the crazy sex life of slipper limpets

Maryna Lesoway from the University of Illinois at Urbana Champaign talks about the sex determination of the slipper limpet Crepidula fornicata.

From Kiel University in Germany:

Oyster deaths: American slipper limpet is innocent

Zoological Museum in Kiel plays a leading role in reconstructing the death of the European oyster

November 27, 2019

Natural history collections are unique archives of biodiversity. They document how living things transform over time and what effects aspects like climate change or other human-made environmental changes have on their distribution. A good example is the decline in numbers of the European oyster (Ostrea edulis) in the North Sea, which has been continuing for over 100 years. Researchers from Kiel University (CAU), in cooperation with the NORe museum association for the North and Baltic Sea region and the Senckenberg Research Institute and Natural History Museum in Frankfurt, have now managed to shine some light on this phenomenon. They have concluded that the occurrence of the invasive American slipper limpet (Crepidula fornicata) is not one of the main causes for the European oyster dying out — unlike previously assumed. The researchers published their study in the journal PLOS ONE in October.

The informative value of natural historical collections

Historical collections of the European oyster and its surrounding fauna form the basis for the new findings. The researchers investigated a total of 1,750 oysters and more than 700 slipper limpets which all found their way into the joint project’s museums and the museums in Leiden and London between 1820 and 2018. “Our unique collection by Karl August Möbius was of key importance here. This collection documented the presence of the oyster throughout Europe around 1870,” reported Dr Dirk Brandis, head of the Zoological Museum in Kiel and private lecturer at the CAU. Möbius conducted research in Kiel during the second half of the 19th century as a zoologist and ecologist. Based on his investigations of oyster presence in domestic waters, with the concept of biocoenosis he also discovered the mutual dependence of different life forms within a community. “We used the various historical archives to prove that the slipper limpet, which was introduced, had nothing to do with the European oyster dying out, although that has been assumed for a long time,” Brandis continued.

Chronological sequence of the spread of the limpet doesn’t match oyster decline

The researchers drew this conclusion from the temporal sequences, which they were now able to trace back. “Around 200 years ago, oyster fishing in the North Sea was a flourishing business,” explained Dr Dieter Fiege from the Senckenberg Research Institute and Natural History Museum in Frankfurt. He continued: “In the years afterwards, however, the Ostrea edulis numbers declined continuously. It was assumed that the appearance of the invasive slipper limpet, Crepidula fornicata, was the reason behind the dramatic decrease in oysters, along with overfishing, cold winters or diseases.”

In actual fact, the slipper limpet — which is native to the coastlines of North America — was introduced to Europe around 1870 but its presence could only be verified after 1934. “According to our findings, the decline in numbers of the European oyster population already began in the late 19th century, so well before the invasive spread of the slipper limpet. We were able to reconstruct this decline in detail,” emphasized CAU doctoral researcher, Sarah Hayer, who is conducting research at the Zoological Museum in Kiel and who accounted for the study as the lead author. “This makes it clear that the competition by an immigrant species did not cause the European oyster to die out,” added Dr Christine Ewers-Saucedo, who was chiefly responsible for collecting and analysing the data in the study at the Zoological Museum in Kiel. The real reason why the European oyster population dramatically declined in its native habitat remains unanswered.

Springtail fossil discovery in Dominican Republic


This is a 2010 video about springtails taken from the BBC’s Life in the Undergrowth documentary series.

From the New Jersey Institute of Technology in the USA:

16-million-year-old fossil shows springtails hitchhiking on winged termite

November 25, 2019

Summary: A newly reported, 16-million-year-old fossil is shedding light on how a group of tiny arthropods may have traversed the globe — by hitchhiking.

When trying to better the odds for survival, a major dilemma that many animals face is dispersal — being able to pick up and leave to occupy new lands, find fresh resources and mates, and avoid intraspecies competition in times of overpopulation.

For birds, butterflies and other winged creatures, covering long distances may be as easy as the breeze they travel on. But for soil-dwellers of the crawling variety, the hurdle remains: How do they reach new, far-off habitats?

For one group of tiny arthropods called springtails (Collembola), a recent fossil discovery now suggests their answer to this question has been to piggyback on the dispersal abilities of others, literally.

In findings published in BMC Evolutionary Biology, researchers at the New Jersey Institute of Technology (NJIT) and Museum national d’Histoire naturelle have detailed the discovery of an ancient interaction preserved in 16-million-year-old amber from the Dominican Republic: 25 springtails attached to, and nearby, a large winged termite and ant from the days of the early Miocene.

The fossil exhibits a number of springtails still attached to the wings and legs of their hosts, while others are preserved as if gradually floating away from their hosts within the amber. Researchers say the discovery highlights the existence of a new type of hitchhiking behavior among wingless soil-dwelling arthropods, and could be key to explaining how symphypleonan springtails successfully achieved dispersal worldwide.

“The existence of this hitchhiking behavior is especially exciting given the fact that modern springtails are rarely described as having any interspecfic association with surrounding animals,” said Ninon Robin, the paper’s first author whose postdoctoral research at NJIT’s Department of Biological Sciences was funded by the Fulbright Program of the French-American Commission. “This finding underscores how important fossils are for telling us about unsuspected ancient ecologies as well as still ongoing behaviors that were so far simply overlooked.”

Today, springtails are among the most common arthropods found in moist habitats around the world. Most springtails possess a specialized appendage under their abdomen they use to “spring” away in flea-like fashion to avoid predation. However, this organ is not sufficient for traversing long distances, especially since most springtails are unable to survive long in dry areas.

The hitchhikers the researchers identified belong to a lineage of springtails found today on every continent, known as Symphypleona, which they say may have been “pre-adapted” to grasping on to other arthropods through prehensile antennae.

Because springtails would have encountered such winged termites and ants frequently due to their high abundance during the time of the preservation, these social insects may have been their preferred hosts for transportation.

“Symphypleonan springtails are unusual compared to other Collembola in that they have specialized antennae that are used in mating courtship,” said Phillip Barden, assistant professor of biology at NJIT and the study’s principal investigator. “This antennal anatomy may have provided an evolutionary pathway for grasping onto other arthropods. In this particular fossil, we see these specialized antennae wrapping around the wings and legs of both an ant and termite. Some winged ants and termites are known to travel significant distances, which would greatly aid in dispersal.”

Barden says that the discovery joins other reports from the Caribbean and Europe of fossil springtails attached to a beetle, a mayfly and a harvestman in amber, which together suggest that this behavior may still exist today.

Barden notes that evidence of springtail hitchhiking may not have been captured in such high numbers until now due to the rarity of such a fossilized interaction, as well as the nature of modern sampling methods for insects, which typically involves submersion in ethanol for preservation.

“Because it appears that springtails reflexively detach from their hosts when in danger, evidenced by the detached individuals in the amber, ethanol would effectively erase the link between hitchhiker and host,” said Barden. “Amber derives from fossilized sticky tree resin and is viscous enough that it would retain the interaction. … Meaning, sometimes you have to turn to 16-million-year-old amber fossils to find out what might be happening in your backyard.”

How mantis shrimp think, new research


This 2013 video says about itself:

World’s Fastest Punch | Slow Motion Mantis Shrimp | Earth Unplugged

The peacock mantis shrimp has the world’s fastest feeding strike of any animal. Can Sam and Si capture this lightning-fast punch?

From the University of Arizona in the USA:

How mantis shrimp make sense of the world

November 25, 2019

A study involving scientists at the University of Arizona and the University of Queensland provides new insight into how the small brains of mantis shrimp — fierce predators with keen vision that are among the fastest strikers in the animal kingdom — are able to make sense of a breathtaking amount of visual input.

The researchers examined the neuronal organization of mantis shrimp, which are among the top predatory animals of coral reefs and other shallow warm water environments.

The research team discovered a region of the mantis shrimp brain they called the reniform (“kidney-shaped”) body. The discovery sheds new light on how the crustaceans may process and integrate visual information with other sensory input.

Mantis shrimp sport the most complex visual system of any living animal. They are unique in that they have a pair of eyes that move independently of each other, each with stereoscopic vision and possessing a band of photoreceptors that can distinguish up to 12 different wavelengths as well as linear and circular polarized light. Humans, by comparison, can only perceive three wavelengths — red, green and blue.

Therefore, mantis shrimp have much more spectral information entering their brains than humans do. Mantis shrimp seem to be able to process all of the different channels of information with the participation of the reniform body, a region of the animal’s brain found in the eyestalks that support its two protruding eyes.

Researchers Hanne Thoen and Justin Marshall at Queensland Brain Institute at the University of Queensland in Brisbane, Australia, teamed up with Nicholas Strausfeld at the University of Arizona, as well as scientists from Lund University in Sweden and the University of Washington in the U.S. to gain a better understanding of how the reniform bodies connect to other parts of the mantis shrimp brain and gather clues to their functional roles.

Using a variety of imaging techniques, the team traced connections made by neurons in the reniform body and discovered that it contains a number of distinct, interacting subsections. One particular subunit is connected to a deep visual center called the lobula, which is structurally comparable to a simplified visual cortex.

“This arrangement may allow mantis shrimp to store quite high-level visual information,” said Strausfeld, senior author of the paper that was published in the Journal of Comparative Neurology.

“Mantis shrimp most likely use these subsections of the reniform body to process different types of color information coming in and organize it in a way that makes sense to the rest of the brain,” said lead author Thoen. “This would enable them to interpret a large amount of visual information very quickly.”

One of the study’s crucial findings was that neural connections link the reniform bodies to centers called mushroom bodies, iconic structures of arthropod brains that are required for olfactory learning and memory.

“The fact that we were now able to demonstrate that the reniform body is also connected to the mushroom body and provides information to it, suggests that olfactory processing may take place in the context of already established visual memories,” said Strausfeld, Regents Professor of neuroscience and director of the Center for Insect Science at the University of Arizona.

The discovery of the reniform body, however, is not limited to mantis shrimp. It has been identified in other species as well, including shore crabs, shrimp and crayfish.

In 2016, an Argentinian group discovered that, in crabs, what are now known as reniform bodies act as secondary centers for learning and memory. According to Strausfeld, this suggests that the formation and storage of memories occurs in at least two different and discrete sites in the brain of the mantis shrimp and likely other members of malacostracans, the largest class of crustaceans. In addition to mantis shrimp, malacostracans include crabs, lobsters, crayfish, shrimp, krill and other less familiar species that together account for about 40,000 living species and a great diversity of body forms.

Reniform bodies have not been identified in insects and may be uniquely crustacean attributes, the researchers say. Alternatively, they might be homologous to a structure found in insect brains called the lateral horn, which sits between the optic lobes and the mushroom bodies. Strausfeld pointed out that fruit fly research done by other groups showed that the lateral horn is crucial in assigning values to learned olfactory information.

“The hunt is now on to determine if insects have a homologous center,” he said. “If we are looking for homologs in other arthropods, the reniform body would be the obvious candidate.”

The study was funded in part by the Asian Office of Aerospace Research and Development (12?4063), the Australian Research Council (FL140100197) and the National Science Foundation (11754798).