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horsehair worm

‘Mind-Controlling’ Parasitic Worms Are Missing 30% of Genes Found in All Other Animals

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Parasitic worms known for their “mind controlling” abilities are missing 30% of genes that are found in all other animals, scientists say. The thread-like worms are notorious for compelling their insect hosts to jump into water and drown.

Horsehair worms, of which there are hundreds of species, hatch in water where small water-dwelling predators eventually eat their larvae. Land-dwelling predators, such as crickets and beetles that consume these smaller predators, make the ideal host for the parasite.

After spending months as larvae inside these larger predators, the adult parasites force their hosts to actively seek out and enter bodies of water. Once the insect has drowned, the horsehair worms swim out of the host’s rear orifices to begin their next generation.

The worms resemble spaghetti strings, are only a few inches long, and are found all around the world. Spending most of their lives inside other animals, they have no excretory, respiratory or circulatory systems.

According to a study published Tuesday in the journal Current Biology, horsehair worms, which belong to the phylum Nematomorpha, lost about a third of the genes found in other animals somewhere along their evolutionary history. Genome sequencing of two nematomorph species—the freshwater hairworm Acutogordius australiensis and the marine species Nectonema munidae—led researchers to find the missing genes. Beyond their unique reproductive behavior, very little was known about the worms’ genetics until now.

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Tauana Cunha, a postdoctoral research scientist at Chicago’s Field Museum of Natural History and lead author of the study, says, “One of the coolest things, maybe the thing that they are most known for, is that they can affect the behavior of their hosts and make them do things that they wouldn’t do otherwise.”

Cunha told CNN that compared with other animals, the worms seemed to be missing a group of around 200 genes.

“There’s a given set of genes that are expected to be found across animal groups. It’s used as a metric for the quality of your genome.”

The genes are known to control the development of cilia—short hairlike structures found at the cellular level, which aid in cellular movement, perform sensing functions, and remove debris and microbes.

The “tail” of a sperm cell is actually just a single, highly specialized cilium. Many microscopic organisms use cilia to swim and catch food. These structures also line our respiratory tract, retinal cells, and the surface of our lungs.

“We set out to sequence their genomes because nothing like them has ever been sequenced before at that level. The goal was to produce those genomes and eventually use them to understand the evolutionary relationships between hairworms and other kinds of animals.”

Horsehair worms seem to be thriving without cilia. “The large majority of the missing genes were exactly the same between the two species; this was just implausible by chance,” says Cunha about the marine and freshwater horsehair worm species studied.

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Biologist Keiichi Kakui, a lecturer in the Department of Biological Sciences at Hokkaido University in Japan, told CNN that the promising new research combines “genome-scale molecular data and detailed morphological observation.”

Kakui was the lead author of a separate study that identified juvenile marine horsehair worms in isopods, a type of deep-sea crustacean. It is unclear how these parasites are able to navigate the ocean without the sensory structures available to most other animals.

“It is hard for me to imagine how this species finds and enters their host in the vast deep sea.”

Scientists had previously identified five species of marine horsehair worms, joining the hundreds of species found in freshwater. Marine horsehair worms, in contrast to their freshwater counterparts, live their entire lives underwater and are not known to manipulate their hosts’ behavior. However, it appears that all species are missing the same genes, which may indicate that both lineages share a common ancestor from which the genetic deficiency was inherited.

Cunha says the new genetic information could also be used to learn about other parasitic organisms known to influence the behaviors of their hosts.

“By doing this comparative analysis across organisms in the future, we might be able to look for similarities. Or maybe these organisms evolved similar behaviors in completely different ways from each other.”

T-Rex

The Reapers Of Death: New T-Rex Species Discovered in Canada

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The fossil remains of a Tyrannosaurus Rex (T. Rex) “cousin species” have been uncovered in Alberta, Canada. Scientists are classifying the meat-eating dinosaur as Thanatotheristes degrootorum, and since they concluded that the remains are over 80 million years old, the T. Rex cousin is being deemed as the oldest known Tyrannosaur on record in North America; “Tyrannosaur” is the general term that covers all subspecies of the T. Rex. 

Scientists are also nicknaming the species the “reapers of death” based on the fact that their fossils show evidence of a “monstrous face”, vicious looking serrated teeth that were likely as sharp as steak knives and 3 inches long, and legs that were 8 feet in length from foot to hip. The fossil evidence also allowed scientists to estimate that the reapers measured in at 26 feet long from snout to tail. 

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“Like other tyrannosaurs, the ‘reaper of death’ had strange bumps on its skull that gave it a monstrous appearance. But it also had a one-of-a-kind feature, a distinct set of vertical ridges that ran from its eyes along its upper snout. These ridges are not like anything we’ve ever seen before in other tyrannosaur species. Exactly what the ridges do, we’re not quite sure,” said study lead researcher Jared Voris, a doctoral student of paleontology at the University of Calgary in Alberta.

Voris and his team also concluded that the reapers of death walked the Earth during the Cretaceous period, which was the final period of the dinosaur age on Earth before they all were wiped out. This also means that these creatures were likely alive 145 million years ago (when the Cretaceous period began). 

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The initial remains that were discovered were found by a Canadian couple on the shore of the Bow River in southern Alberta. That was back in 2010, and at the time it was believed that the only dinosaurs who lived in the Alberta area, hundreds of millions of years ago, were plant eaters. So 10 years ago it was believed that the mysterious skull remains that the couple found were just another Triceratops relative of sorts; even though the skull remains were abnormally three feet in length.

Once Voris began his own personal research regarding new dinosaur species he was able to determine that those decade old remains were actually the reapers of death, and not just another herbivore. In fact, based on their new conclusions they’ve determined that the reapers likely ate a majority of the herbivores that did live in Alberta. 

“The new discovery shows that Daspletosaurus-like tyrannosaurs were diversifying in the northern part of western North America about 80 million years ago. But these long- and deep-snouted tyrannosaurs appeared to stay in their neck of the woods. This seems to be a bigger theme: There were different subgroups of tyrannosaurs characteristic of certain times and places, and they did not all mix together,” said Steve Brusatte, a paleontologist at the University of Edinburgh in Scotland. 

While the reapers of death weren’t as large as their more well known younger T. Rex cousins, their remains give scientists a great insight into the vastly diverse world of dinosaurs. Paleontologists and scientists alike can never be fully satisfied with their “conclusive” data regarding dinosaurs because they lived millions of years ago, making it close to impossible to know about every detail and subspecies that pertained to their time on Earth. However, discoveries such as this open dozens of doors in terms of possibilities for what other kinds of dinosaurs were roaming the Earth and where.