Cambrian animals’ eyes, new research


This video says about itself:

Colours of Life – The Evolution of Colour Vision Expressed in Musical Colours – Iris Stal

23 August 2018

A composition by Iris Stal.

This is a composition I wrote for a university assignment for a course on interdisciplinary evolution. It’s the very first composition I’ve ever written! 🙂 This piece for orchestra is supposed to express how colour vision has evolved throughout its evolutionary timeline, using musical colours.

Our eyes use cones to detect the colours in the light waves that we pick up. In the music, I attempted to explain which cones came up with which group of animals and how that affected the way they saw their environment. If important, I also tried to take important events or circumstances along in the atmosphere, such as natural selection influences or extinctions. I followed the lineage from one of the very first light-sensitive eyecups all the way up to human eyes. Lineages that branched off I didn’t include as it would be too much.

The coloured bars on the left show what cones the animals had. The cones symbolize cones for blue light, red, green and UV. I used video footage and/or illustrations that I edited to show how the species potentially perceived their environment. It’s not super accurate, but it’s hard imitating a colour the human eye can’t see. 😀 Looking at you, ultraviolet!

This project was sooo much fun to create! It was tons of work but it was absolutely worth the effort. I finished the project with a 9/10. It inspired me to continue with my passion for music. I hope you enjoy the video! 🙂

From the University of Bristol in England:

Enhancing our vision of the past

December 5, 2018

An international group of scientists led by researchers from the University of Bristol have advanced our understanding of how ancient animals saw the world by combining the study of fossils and genetics.

Ancestors of insects and crustaceans that lived more than 500 million years ago in the Cambrian period were some of the earliest active predators, but not much is known about how their eyes were adapted for hunting.

Work published in the Proceedings of the Royal Society B today suggests that when fossil and genetic data are assessed in tandem, previously inaccessible and exciting conclusions about long dead species can be made.

By examining the morphological characteristics of fossils’ eyes, alongside the genetic visual pigment clues, a cross-disciplinary team led by a collaboration between the University of Bristol’s Davide Pisani, Professor of Phylogenomics in the School of Earth Sciences and Nicholas Roberts, Professor of Sensory Ecology in the School of Biological Sciences, were able to find that ancient predators with more complex eyes are likely to have seen in colour.

Professor Pisani remarked: “Being able to combine fossil and genetic data in this way is a really exciting frontier of modern palaeontological and biological research. Vision is key to many animals’ behaviour and ecology, and understanding how extinct animals perceived their environment will help enormously to clarify how they evolved.”

By calculating the time of emergence of different visual pigments, and then comparing them to the inferred age of origin of key fossil lineages, the researchers were able to work out the number of pigments likely to have been possessed by different fossil species. They found that fossil animals with more complex eyes appeared to have more visual pigments, and that the great predators of the Cambrian period may have been able to see in colour.

Dr James Fleming, Professor Pisani and Roberts’ former PhD student, explained: “Animal genomes and therefore opsin genes (constituting the base of different visual pigments) evolve by processes of gene duplication. The opsin and the pigment that existed before the duplication is like a parent, and the two new opsins (and pigments) that emerge from the duplication process are like children on a family tree.

“We calculated the birth dates of these children and this allowed understanding of what the ancient world must have seemed like to the animals that occupied it. We found that while some of the fossils we considered had only one pigment and were monochromat, i.e. they saw the world as if looking into a black and white TV, forms with more complex eyes, like iconic trilobites, had many pigments and most likely saw their world in colours.”

The combinations of complex eyes and multiple kinds of visual pigments are what allows animals to distinguish between different objects based on colour alone — what we know as colour vision.

Professor Roberts commented: “It is remarkable to see how in only a very few million years the view those animals’ had of their world changed from greys to the colourful world we see today.”

The project involved scientists from all across the world — from the UK as well as Denmark, Italy, Korea and Japan, where Dr Fleming has now moved to work as a postdoctoral researcher. Each of them brought their own specialities to this multidisciplinary work, providing expertise in genetics, vision, taxonomy and palaeontology.

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Dragonfly larvae, beautiful new book


Damselflies, by Paul Andre Robert

From KNNV publishers in the Netherlands:

Les larves de libellules de Paul-André Robert | Die Libellenlarven von Paul-André Robert

Author: Christophe Brochard | Paul-André Robert
Price: € 89,95

Paul-André Robert (1901-1977) was a Swiss artist and naturalist. In Europe Robert is best known for his book Les Libellules (‘Dragonflies’), which appeared in 1958. Less well-known is the fact that Robert began to work on a monumental monograph on European dragonfly larvae at the age of sixteen. Producing the manuscript, containing text as well as illustrations, consumed most of his life and was only just completed at the time of his death.

This magnificent work remained unpublished until now. This book finally presents Robert’s 107 watercolour illustrations of dragonfly larvae, all in their original size and of unparalleled beauty and scientific precision. In addition, the book features his numerous line drawings and pencil sketches of morphological details, descriptions of species and an identification key.

This book, which is bilingual (French and German), is a unique combination of art and science. It is an invaluable resource for entomology professionals and a significant collector’s item for admirers of high-quality entomological books. It is also a stunning piece of artwork that will please anyone with an interest in natural history, realistic art and illustration.

As an honorary tribute to Robert, an international team of dragonfly experts added an extensive introduction to the book.

ISBN: 9789050116831
Edition: 1
Pages: 320
Size: 22 x 28 cm
full colour, hardcover

Variable damselfly larvae, by Paul-André Robert

This picture by Paul-André Robert shows variable damselfly larvae.

First jellyfish genome sequenced


This 30 November 2015 video says about itself:

Formerly Considered Single-Celled, This Parasite Is Actually A Jellyfish

Genome sequencing of myxozoans has determined that the parasitic creatures are microscopic jellyfish—challenging our definition of what an animal is.

A common aquatic parasite, long-studied for its devastating impact on commercial fishing, is essentially a microscopic jellyfish. Researchers from the University of Kansas, or KU, sequenced the genome of myxozoans and discovered the parasites are “highly reduced” cnidarians—belonging to the same phylum as jellyfish, sea anemones and corals.

The team also discovered that myxozoa have an extremely small genome, several orders of magnitude less complex than typical jellyfish. One thing they do have in common is their stinger.

Paulyn Cartwright, the project’s principal investigator, explained, “Because they’re so weird, it’s difficult to imagine they were jellyfish. They don’t have a mouth or a gut. They have just a few cells. But then they have this complex structure that looks just like the stinging cell of cnidarian.”

Originally considered single-celled organisms, myxozoa are rewriting the biological textbook. That’s because the parasites lack a certain type of gene previously believed necessary for animal development.

But Cartwright is adamant, “Myxozoa is definitely an animal because its evolutionary origin is shared with jellyfish, and we use species’ ancestry to define them. But animals are usually defined as macroscopic multicellular organisms, and this is not that. Myxozoa absolutely redefines what we think of as animal.”

From the University of California – Davis in the USA:

First jellyfish genome reveals ancient beginnings of complex body plan

December 3, 2018

Summary: The first in-depth look at the genome of a jellyfish — the moon jelly Aurelia aurita — shows that early jellyfish recycled existing genes to gain the ability to morph from polyp to medusa.

Jellyfish undergo an amazing metamorphosis, from tiny polyps growing on the seafloor to swimming medusae with stinging tentacles. This shape-shifting has served them well, shepherding jellyfish through more than 500 million years of mass extinctions on Earth.

“Whatever they’re doing has really worked for them,” said David Gold, an assistant professor of paleobiology in the UC Davis College of Letters and Science.

The first in-depth look at the genome of a jellyfish — the moon jelly Aurelia aurita — reveals the origins of this successful survival strategy. The Aurelia genome, published online Dec. 3 in the journal Nature Ecology and Evolution, indicates early jellyfish recycled existing genes to morph from polyp to medusa. The results suggest animals can radiate into new niches and forms fairly easily.

“These findings provide further evidence that evolution doesn’t necessarily make the genetic code more complex”, said Gold, a lead researcher on the genome study. “Jellyfish can build a big, complex life history using many of the same genes found in simpler animals.”

The research team was led equally by Gold, who performed much of the work as a postdoctoral fellow at the California Institute of Technology, and by Takeo Katsuki, a project scientist at the Kavli Institute for Brain and Mind at UC San Diego.

The genome: a multi-use tool

Jellyfish come from one of the oldest branches on the animal family tree, the phylum Cnidaria, which includes corals and anemones. Jellyfish were probably the first muscle-powered swimmers in the open ocean. They appeared in the late Precambrian Era, a period of major geologic and ecological changes that preceded the Cambrian explosion of animal life.

At some point in their evolution, jellyfish gained the ability to transition from a stationary polyp to a swimming medusa. The transition involves major changes in the jellyfish nervous system, muscles and weaponry, aka the stinging cells called cnidocytes. To accomplish this, the medusa life stage often co-opts existing developmental gene networks and cell types present in polyps, the researchers found. In addition, Aurelia appears to pattern its different life stages using many of the same genes found in animals such as fruit flies and humans, the study reports. (all of these animals share a common ancestor, albeit an ancient one.)

There is a second, more controversial explanation for what the scientists found in the jellyfish genome. Perhaps the similarities between the moon jellyfish genome and “higher” animals demonstrates that the Cnidaria originally had a medusa life stage, which animals like corals and sea anemones lost.

“Our results can’t distinguish between these two scenarios”, said Gold. If the second hypothesis turns out to be correct, “Swimming, carnivorous animals may be even older than we think.” In addition to questions of evolution, the Aurelia genome will prove valuable in many other areas of biology, Gold said. Aurelia is an important model for studying the development and function of nervous systems, and can offer insights into animal wound healing and regeneration. Moon jellies are also a major culprit in environmentally and economically damaging jellyfish blooms, which are becoming more common. For example, giant swarms of moon jellies have clogged water-intake pipes, forcing the shutdown of nuclear plants in Florida and Sweden. An improved understanding of Aurelia genetics could offer new ideas for controlling the blooms.

“In many ways, the ancient oceans in the late Precambrian are very much like what the modern oceans will look like in the near future,” Gold said “meaning studying how jellyfish evolved in the past can tell us about their potential impact on the future.”

Beetle larvae survive dry summer


This September 2018 video is about the hot dry summer in the Netherlands. Quite some larvae of cockchafer beetles and garden chafer beetles, hatched from spring 2018 eggs, managed to survive the difficult circumstances.

The video is by Silvia Hellingman from the Netherlands.

Spider mothers’ milk for babies


This 29 November 2018 video says about itself:

This small jumping spider is nursing her young with milk | Science News

Female Toxeus magnus spiders, native to tropical and subtropical areas in Asia, produce nutrient-rich milk to feed their young for weeks, even after the spiderlings begin to hunt on their own. Here, a 1-week-old juvenile nurses an area of its mother’s abdomen from which the milk is available.

Read more here.

From the Chinese Academy of Sciences Headquarters:

Mammal-like milk provisioning and parental care discovered in jumping spider

November 29, 2018

Summary: Researchers report milk provisioning in Toxeus magnus (Araneae: Salticidae), a jumping spider that mimics ants. Milk provisioning in T. magnus involves a specialized organ over an extended period, similar to mammalian lactation. The study demonstrated that mammal-like milk provisioning and parental care for sexually mature offspring have also evolved in invertebrates.

Lactation is the production and secretion of milk for the young and is a mammalian attribute. However, there have been few examples of milk provisioning in non-mammals.

In a study published in the journal Science on November 30, researchers at the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences report milk provisioning in Toxeus magnus (Araneae: Salticidae), a jumping spider that mimics ants.

In a field study, researchers observed a jumping spider species whose breeding nest is composed of either several large individuals, with two or more adults, or one adult female and several juveniles.

“It’s a puzzling observation for a species assumed to be noncolonial. It’s possible that the jumping spider might provide either prolonged maternal care or delayed dispersal. We decided to test it,” said Dr. CHEN Zhanqi, the first author of the study.

The researchers assessed how offspring developed and behaved under maternal care both in laboratory conditions and in the field. No spiderlings were observed leaving the nest for foraging until they were 20 days old.

Closer observation revealed that the mother provided a seemingly nutritive fluid, hereafter called milk, to the offspring.

Milk provisioning in T. magnus involves a specialized organ over an extended period, similar to mammalian lactation. Observations under the microscope showed droplets leaking from the mother’s epigastric furrow where the spiderlings sucked milk.

The spiderlings ingest nutritious milk droplets secreted from the mother’s epigastric furrow until the subadult stage (around 40 days). If blocked from obtaining milk, the newly emerged spiders will stop development and die within 10 days, showing that milk is indispensable for offspring survival in the early stage.

Moreover, the researchers tested why parental care and milk provisioning were continued after 20 days when the spiderlings were able to forage for themselves.

The mother continued nest maintenance throughout, carrying out spiderlings’ exuviae and repairing nest damage. When receiving both maternal care and milk, 76% of the hatched offspring survived to adulthood (around 52 days).

Milk provisioning after 20 days did not affect adult survivorship, body size, sex ratio or development time, but the mother’s presence played a key role in assuring a high adult survival rate and normal body size. Thus, milk provisioning complemented their foraging in later stages.

Although the mother apparently treated all juveniles the same, only daughters were allowed to return to the breeding nest after sexual maturity. Adult sons were attacked if they tried to return. This may reduce inbreeding depression.

The findings show that in the jumping spider species, the mother invests much more than the male invests, predicting a female-biased sex ratio to be optimal for reproductive success with a polygamous mating system.

“Our findings demonstrate that mammal-like milk provisioning and parental care for sexually mature offspring have also evolved in invertebrates,” said Dr. CHEN. “We anticipate that our findings will encourage a reevaluation of the evolution of lactation and extended parental care and their occurrences across the animal kingdom.”

Zombie shrimp playing dead


This video from the Monterey Bay Aquarium Research Institute (MBARI) in California in the USA says about itself:

Zombie shrimp play dead to avoid being eaten

28 November 2018

While exploring the depths of the Gulf of California with the remotely operated vehicle Doc Ricketts, MBARI researchers saw an eerie sight: the small shrimp, Hymenopenaeus doris, hanging upside down, motionless in the water. At first, the shrimp appeared dead, but a closer look revealed that the animal was making tiny adjustments of its antennae and legs to maintain a head-down position while very slowly sinking. When the submersible got too close, the shrimp sprang back to life and quickly swam away.

While performing this “zombie-like“ behavior, the shrimp looked a lot like a discarded exoskeleton sinking slowly through the dark midwater. The researchers speculate that the shrimp might reduce their chances of being eaten by mimicking a sinking molt.

This odd behavior might also be an adaptation to conserve energy, since the shrimp live at depths where the seawater contains very little oxygen. Animals found in low-oxygen environments have a harder time moving rapidly or for long distances.

The researchers observed three zombie shrimp hanging right underneath large mucous webs or nets. Many deep-sea animals use mucous webs to gather marine snow (small particles of debris drifting down from the surface) for food. The biologists were unable to confirm a connection between the shrimp and the webs, leaving this mystery to be solved on a future expedition.

For more information see here.

Publication: Burford BP, Schlining KL, Reisenbichler KR, Robison BH (2018) Pelagic shrimp play dead in deep oxygen minima. PLoS ONE 13(11): e0207249.

Video editor: Kyra Schlining
Music: Stranger Danger (YouTube audio library)