Image credit: Aziz Aboobaker, Edinburgh
Image credit: Aziz Aboobaker, Edinburgh

The Tardigrade’s Extraordinary Weirdness Continues

Image credit: Aziz Aboobaker, Edinburgh
Image credit: Aziz Aboobaker, Edinburgh

The mystery of the tardigrade—a.k.a. moss piglet, a.k.a. water bear—is one step closer to a solution. Scientists studying the microscopic animals' DNA say the tough, many-legged creatures may be distantly related to nematodes and other "wormy things." The researchers published their findings in the journal PLOS Biology.

Tardigrades are some of the strangest, most badass organisms on Earth. Don't be fooled by their tiny size—these animals are anything but delicate. They can survive in the most brutal conditions, from dehydration and starvation to burning heat, blistering cold, intense radiation, and even the vacuum of space.

How they pull off this near-invincibility is, naturally, a question of some interest among biologists (and to Mental Floss—links to our many articles about these amazing creatures are found throughout this story).

The authors of one 2015 study made headlines when they announced that one-sixth of the tardigrade's genetic blueprint had been swiped from bacteria and other organisms. This horizontal gene transfer (HGT) is not unheard of in nature, but other tardigrade experts, including a team at the University of Edinburgh, felt that 17.5 percent seemed suspiciously high, even for a maverick like the tardigrade.

The skeptics were right. Additional investigation into the tardigrade genome confirmed the presence of a few horizontally transferred genes. Just a few.

HGT aside, there's still plenty to discover in the tardigrade's genes. Tardigrades have been tardigrades for hundreds of millions of years. No fossils remain from their early days to tell us what they might have been before. We don't really know where they came from, evolutionarily speaking, or who their relatives are.

To find out, Edinburgh researcher Mark Blaxter and his colleagues picked apart the genomes of two tardigrade species, Ramazzottius varieornatus and Hypsibius dujardini. They found something unexpected: The armored, many-legged tardigrades seemed more closely related to worms than to insects.

If these findings are accurate, Blaxter told Mental Floss in an email, they challenge the very structure of the Panarthropoda family tree, which assumes "the leggy moulting animals are more closely related to each other than they are to wormy things like nematodes."

But he notes that there's lots more research to be done before issuing that challenge: "We have only looked at a tiny fraction of the 10 or more million species on Earth. Every new group, and possibly every species, will have something exciting in it we haven't seen before, and didn't imagine."

Scientists Capture the First Footage of an Anglerfish’s Parasitic Mating Ritual

The deep sea is full of alien-looking creatures, and the fanfin anglerfish is no exception. The toothy Caulophryne jordani, with its expandable stomach and glowing lure and fin rays, is notable not just for its weird looks, but also its odd mating method, which has been captured in the wild on video for the first time, as CNET and Science report.

If you saw a male anglerfish and a female anglerfish together, you would probably not recognize them as the same species. In fact, in the video below, you might not be able to find the male at all. The male anglerfish is lure-less and teeny-tiny (as much as 60 times smaller in length) compared to his lady love.

And he's kind of a deadbeat boyfriend. The male anglerfish attaches to the female's belly in a parasitic mating ritual that involves biting into her and latching on, fusing with her so that he can get his nutrients straight from her blood. He stays there for the rest of his fishy life, fertilizing her eggs and eventually becoming part of her body completely.

Observing an anglerfish in action, or really at all, is extremely difficult. There are only 14 dead specimens from this particular anglerfish species held at natural history museums throughout the world, and they are all female. Since anglerfish can't live in the lab, seeing them in their natural habitat is the only way to observe them. This video, shot in 2016 off the coast of Portugal by researchers with the Rebikoff-Niggeler Foundation, is only the third time we've been able to record deep-sea anglerfish behavior.

Take a look for yourself, and be grateful that your own relationship isn't quite so codependent.

[h/t CNET]

Cockroach DNA Shows Why They're Basically Indestructible

Most people are all too aware that cockroaches are horrifyingly resilient beings. Yes, they can and have survived nuclear blasts, and surely stand to inherit the Earth after we all succumb to the apocalypse. Why is this creature able to thrive in the face of pesticides, the loss of limbs, disgusting conditions, a range of climates, and even nuclear fallout, in urban kitchens across the world? As Inside Science reports, a new study on the genome of the American cockroach shows that certain genes are key to its wild evolutionary success.

In an article published in Nature Communications, researchers from South China Normal University in Guangzhou, China report that they sequenced and analyzed the genome of Periplaneta americana, and in the process they discovered just how indestructible this scourge is. They found that the cockroach (native to Africa, despite its American moniker) has more DNA than any other insect whose DNA has been sequenced except the migratory locust. The size of its genome—3.3 billion base pairs—is comparable to that of humans.

They have a huge number of gene families (several times the number other insects have) related to sensory reception, with 154 smell receptors and 522 taste receptors, including 329 taste receptors specifically related to bitter tastes. These extra smell and taste receptors may help cockroaches avoid toxic food (say, your household pesticide) and give them the ability to adapt to a multitude of different diets in different environments.

They also have killer immune systems able to withstand pathogens they might pick up from the rotting food they eat and the filth they like to live in. They have many more genes related to immunity compared to other insects.

The genome analysis might give us more than just a newfound respect for this revolting pest. The researchers hope to find a way to harness this new knowledge of cockroach immunity to control vermin populations—and create an eradication method slightly more effective than just stomping on them.

[h/t Inside Science]


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