Fossil invertebrates, new study


This vido says about itself:

12 January 2017

For 175 years, a cone-shaped, shelled prehistoric creature called a hyolith has been waiting to be assigned a proper place on the tree of life. Thanks to a recent research effort, the hyolith’s wait is over.

From Science News:

Ancient oddball invertebrate finds its place on the tree of life

by Cassie Martin

2:30pm, January 11, 2017

Hyoliths are evolutionary misfits no more.

This class of ancient marine invertebrates has now been firmly pegged as lophophorates, a group whose living members include horseshoe worms and lamp shells, concludes an analysis of more than 1,500 fossils, including preserved soft tissue.

The soft-bodied creatures, encased in conical shells, concealed U-shaped guts and rings of tentacles called lophophores that surrounded their mouths. Fossil analysis suggests that hyoliths used those tentacles and spines, called helens, to trawl the seafloor more than 500 million years ago, researchers report online January 11 in Nature.

For years, paleontologists have argued over where on the tree of life these bottom-feeders belonged. Some scientists thought hyoliths were closely related to mollusks, while others thought the odd-looking creatures deserved a branch all their own. This new insight into hyolith anatomy “settles a long-standing paleontological debate,” the researchers write.

Sea spider anatomy, new research


This video says about itself:

6 July 2015

Quick facts about these thin-legged arthropods! The Sea Spider (Pycnogonida/Pantopoda)! Sea Spider facts!

From Science News:

It takes guts for a sea spider to pump blood

These arthropods’ unusual digestive system can act like a heart and gills

By Susan Milius

4:46pm, January 11, 2017

NEW ORLEANS — A newfound way of delivering oxygen in animal circulatory systems depends mostly on food sloshing back and forth in the guts.

This discovery came in sea spiders, or pycnogonids, which can look like legs in search of a body. Their spookily long legs hold stretches of digestive tract, which wouldn’t fit inside the creatures’ scrap of an abdomen. Waves of contraction sweeping up and down the leggy guts cause blood outside the guts to move too, evolutionary physiologist Art Woods of the University of Montana in Missoula said January 8 at the annual meeting of the Society for Integrative and Comparative Biology. As lumpy surges of partly digested food rise and fall, blood that has picked up oxygen by diffusion whooshes to the rest of the body, Woods proposed.

“Essentially they use their legs like gills,” says Jon Harrison, an evolutionary physiologist at Arizona State University in Tempe, who was not involved in the research. “To my knowledge, no one had thought of this before — certainly no one has demonstrated this before.”

The roughly 1,300 sea spider species aren’t true spiders but a closely related lineage of arthropods. They feed via a long proboscis that doesn’t punch into food but gnaws at it bit by bit and then sucks up the smaller nuggets. Those nuggets typically come from hunting or scavenging other invertebrates. Jellyfish and hydroids are some sea spiders’ favorites with occasional other snacks such as clams or sea slugs. Various sea spider species live from the tropics to the poles, and in Antarctica, sea spiders grow to a leg span wider than a dinner plate.

Woods and colleagues were studying this polar gigantism when they began thinking through the spiders’ oxygen consumption. A sea spider’s outer covering is porous enough for oxygen to diffuse through. But the researchers calculated that mere diffusion without some kind of inner pump couldn’t meet these animals’ oxygen needs.

Most sea spider species have a heart and, like other arthropods, an open circulatory system. The heart shoots a pulse of blood out open-ended vessels where it washes over body tissues and then flows back into the heart’s uptake plumbing.

A sea spider heart might boost flow to such blood-hungry zones as the muscular proboscis, but the researchers didn’t see big, regular pulses of blood radiating outward through the body. Hearts probably aren’t the whole story for circulation, Woods concluded.

The researchers also observed that there’s more oxygen in the tips of the legs. Gut activity could then drive the newly oxygenated blood up the leg toward the rest of the body. A video showed a stretch of gut bulging wide inside the leg as a dollop of food washed through, shrinking as the wake died away and then swelling again as a food wave arrived from the opposite direction. These motions inside gut tissue let the oxygen-enriched blood circulate, Woods proposed.

To test the idea, the researchers lowered the oxygen content of water around sea spiders. The movements of the digestive tract increased, as expected if the guts had to work harder to supply oxygen. And when researchers raised the water temperature for both polar and temperate species, which revs up metabolism and increases oxygen demand, gut activity increased, too.

Woods proposes that sea spider blood circulation by gut motion might prove to be what paleontologist Stephen Jay Gould called an exaptation, a trait with one function that over the course of evolution takes on another. Woods’ guess: The digestive system formed first and later happened into circulation.

New Samoan beetle species discovered, already extinct


Holotype specimen of Bryanites graeffii. Image credit: J.K. Liebherr

From Sci News:

Bryanites graeffii: New Beetle Species Described from 150-Year-Old Museum Specimen

Jan 11, 2017 by News Staff

A new species of ground beetle has been identified by Cornell University Professor James Liebherr.

Bryanites graeffii is described from Samoa based on a single male specimen collected between 1862-1870 that was recently discovered in the Muséum national d’Histoire naturelle, Paris,” Prof. Liebherr said.

“The species epithet honors Dr. Eduard Graeffe, zoologist and naturalist from Zurich, Switzerland who collected the specimen while working in Samoa from 1862-1870. The species epithet is formed from Gräffe converted to Latin iconography, and without the terminal letter,” he explained.

The new species belongs to Bryanites, a genus of beetles in the family Carabidae that was previously known from two species represented by two specimens only, collected in 1924 from Savai’i Island, Samoa, by Edwin H. Bryan, Jr., Bernice P. Bishop Museum in Honolulu, during the Bishop Museum’s Whitney South Seas Expedition.

Much like the rest of the species within the genus, Bryanites graeffii showed vestigial flight wings and other traits associated with flight-wing loss.

However, at length of 1.62 cm it is the largest for the taxonomic group it is now assigned to.

Although this may seem way too obvious for taxonomists to overlook, the beetle’s relatives are just as obscure.

“As a result, we now have three species representing an evolutionary radiation in Samoa, all known from single specimens collected long ago,” Prof. Liebherr said.

The phylogenetics of the three Bryanites species link them to other groups from Fiji and New Zealand.

“What is the advantage of knowledge about species that existed some 90-150 years ago, but no longer? It might actually point us to the actual level of impact mankind has on natural ecosystems,” Prof. Liebherr said.

“The cause of the likely extermination of Bryanites graeffi might never be known with certainty, however, the colonization of many Pacific islands by the Polynesian rat has always been followed by the diminution or elimination of native insect species.”

“Thus, we can add another likely victim to the list of species that have been adversely impacted by mankind’s commensal voyagers.”

A detailed description of Bryanites graeffii appears in the Jan. 5 issue of the journal Zoosystematics and Evolution.

Palm warblers eat insects from spiders’ webs


This video from the USA says about itself:

9 January 2017

Several Palm Warblers hunt for insects in spiders‘ webs in the morning – just like going to the grocery store! The spiders do all the hard work and the Warblers wisely reap some rewards. This behavior has apparently not been too well documented on video, although there is a technical name for this that I just learned – Kleptoparasitism (a form of feeding in which one animal takes prey or other food from another that has caught, collected, or otherwise prepared the food, including stored food). Always something new to learn by observing Nature!

Here is a link to a short scientific paper on the subject.

Three new flatworm species discovered in Brazil


This video says about itself:

Huge flatworm (Platyhelminthes) on the move

16 August 2009

We discovered this flatworm on one of our nightly walks in the jungle of Itatiaia National Park in Brazil.

From Phys.org:

Hidden diversity: 3 new species of land flatworms from the Brazilian Araucaria forest

January 9, 2017

A huge invertebrate diversity is hidden on the forest floor in areas of the Araucaria moist forest, Brazil. Land flatworms constitute a numerous group among these invertebrates occurring in the Neotropical region. Flatworms are considered to be top predators within the soil ecosystem, preying on other invertebrates.

The Araucaria moist forest is part of the Brazilian Atlantic Rain Forest and is considered a hotspot of land flatworm diversity, harboring many yet undescribed species. A study recently published in the open access journal ZooKeys describes three new species from areas covered by Araucaria moist forest in South Brazil, which belong to the Neotropical genus Cratera.

Land flatworms lack a water retention mechanism and have a low tolerance to intense changes in temperature and humidity. Their low vagility leads to the existence of a high number of endemic species. Thus, they are considered good bioindicators of the degree of impact on their habitat.

The new species are named after characteristics of their color pattern and are probably endemic for the study areas. Besides differing from each other, as well as from other species of the genus, by their characteristic color pattern, they also show other distinguishing features in the reproductive system. The study provides an identification key to the species of the genus.

The work was conducted by the south Brazilian research group on triclads, led by Dr. Ana Leal-Zanchet, of the Universidade do Vale do Rio dos Sinos (UNISINOS), in southern Brazil. The study was supported by the Brazilian Research Council (CNPq).

Flatworms in the Netherlands: here.

Acorn worms, new research


This video says about itself:

29 November 2016

What if humans could regrow an amputated arm or leg, or completely restore nervous system function after a spinal cord injury?

A new study of one of our closest invertebrate relatives, the acorn worm, reveals that this feat might one day be possible. Acorn worms burrow in the sand around coral reefs, but their ancestral relationship to chordates means they have a genetic makeup and body plan surprisingly similar to ours.

Read more here.

From Science News in the USA:

These acorn worms have a head for swimming

Putting off trunk development may make catching prey easier, researchers say

By Emily DeMarco

10:00am, January 3, 2017

Certain marine worms spend their larval phase as little more than a tiny, transparent “swimming head.” A new study explores the genes involved in that headfirst approach to life.

A mud flat in Morro Bay, Calif., is the only known place where this one species of acorn worm, Schizocardium californicum, is found. After digging up the creatures, Paul Gonzalez, an evolutionary developmental biologist at Stanford University, raised hordes of the larvae at Stanford’s Hopkins Marine Station in Pacific Grove, Calif.

Because a larva and an adult worm look so different, scientists wondered if the same genes and molecular machinery were involved in both phases of development. To find out, Gonzalez and colleagues analyzed the worm’s genetic blueprint during each phase, they report online December 8 in Current Biology.

Genes linked to trunk development were switched off during the larval phase until just before metamorphosis. Instead, most of the genes switched on were associated with head development, Gonzalez says.

The larvae hatch from eggs laid on the mud. When tides flood the area, the squishy, gel-filled animals use hairlike cilia to swim upwards to devour bits of algae. “They’re feeding machines,” Gonzalez says. He speculates that being balloon-shaped noggins, rather than wriggling noodles, may help the organisms float and feed more efficiently.

After about two months of gorging at the algae buffet, the larvae, which grow to roughly 2 millimeters across, transform and sink back into the muck. There, they eventually grow a body that can stretch up to about 40 centimeters.