Are you stressed? The puppy passing by also cares | Nature Trumpet

Shark struck by boat

Recently, scientists recorded for the first time the entire process of a shark becoming "closed" after being hit by a ship.

Shark and boat collide | References [2]

In order to study the behavior of basking sharks, scientists attached a tracker and camera to a basking shark in Ireland and then released it back into the ocean. In the next few hours, the basking shark spent most of its time close to the surface of the water filtering plankton, and occasionally dived. Then, it suddenly made an evasive move, and then the keel of a ship passed behind its dorsal fin. The injured basking shark rolled in the water and swam faster to the bottom of the sea.

After being hit, the basking shark immediately hid on the seafloor. In the next 7 hours, it did not eat or start other normal behaviors. After 7 hours, the tracker was released and scientists lost contact with the basking shark. No one knows whether it has finally recovered from the impact . The video shows that the shark's skin has abrasions and paint marks from the boat, but there are no obvious open wounds, but such non-fatal injuries may also have long-term effects on the animal.

A basking shark's back was bruised by a boat strike | References [2]

The basking shark is the second largest living fish known to date, with a body length of more than 6 meters, but it is still very vulnerable to human ships . Moreover, basking sharks usually sink to the bottom of the sea after death, and it is difficult for scientists to estimate their mortality rate after being hit by ships. Currently, basking sharks have been listed as endangered species by the IUCN, and collisions from ships may push them to the path of extinction.

Basking sharks are giant filter feeders that pose no threat to humans | Wikimedia Commons

How Human Stress Affects Dogs

Dogs can feel pressure from humans, even if the humans are strangers to them.

In a new study, scientists recruited 18 pairs of dogs and their owners, and a group of volunteers who did not know the dogs. They first asked the volunteers to do math problems nervously and watch videos relaxedly , and then collected sweat samples from the volunteers in different states.

The dogs were first trained - bowls were placed in two fixed locations in the room, one with treats and the other without; after the puppies learned this, they would always rush to the bowl with treats faster. At the beginning of the test, the puppies needed to smell the sweat of unfamiliar volunteers first; at this time, the bowls in the room would appear randomly in new locations, and the dogs did not know whether there were treats in them. Scientists want to know whether the volunteers' sweat in different states will affect the speed at which the puppies rush to the bowls in unfamiliar locations.

Before testing, the dog sniffs a sweat sample in a small jar | University of Bristol

If the dogs smelled the sweat of the volunteers doing math problems, they would not approach the new bowl, which means they did not believe there was food in it and were in a depressed and negative state. On the contrary, if the dogs smelled the sweat of humans in a relaxed state, they were more positive and more willing to explore the new bowl, expecting there would be snacks in it.

A dog in an experiment runs to a new bowl to see if there is food inside. | University of Bristol

This study shows that dogs are not only sensitive to their owners' emotions, but also to the emotions of strangers . This influence does not require actual contact, but can be spread through the air through smell and directly affect the dog's mood. When the owner walks on the road with his dog, the nervousness of passers-by may make the dog sad and change its behavior.

So, your bad mood is not ignored by everyone, a strange dog passing by may care about it!

Monitor Lizard Teeth

The Komodo dragon's teeth are actually covered with a layer of iron!

Komodo dragons are the largest lizard species in the world, with males reaching 3 meters in length and weighing 150 kilograms. They are top predators with strong attack power, eating whatever they catch, including mammals, birds and invertebrates, even buffalo.

You can tell he's a ruthless person at first glance | Christoph Moning / Wikimedia Commons

Recently, scientists studied the teeth of Komodo dragons and discovered their attack power buff - the iron coating on their teeth. They have razor-like teeth, and the tips and serrated edges of their teeth have an orange, iron-rich coating , which can make their teeth sharper and invincible.

Scientists speculate that carnivorous dinosaurs may have had similar iron coatings on their teeth, but they were not preserved in fossils, so no related discoveries have been made before.

Komodo dragons have an iron-rich coating on their teeth | References [4]

Unfortunately, although the Komodo dragon has a strong predatory ability, due to human activities and climate change, their habitat has been lost in large quantities, and their population has dropped sharply . They are now listed as an endangered species. 25 years ago, there were 5,000 to 8,000 Komodo dragons in the wild; in recent years, there are only about 1,000 adult individuals left in the wild.

Wasps collectively change sex

Wasps are collectively changing sex because of a type of bacteria!

These bacteria, called Wolbachia, are the most widespread symbiotic bacteria in the world. When they live inside the cells of wasps, they can turn all the wasps in a colony into females. They do everything they can to kill the males in the cradle—kill male embryos, promote parthenogenesis, and even give males female characteristics.

Wolbachia bacteria removed from an insect | Scott O'Neill / Wikimedia Commons

Why eliminate males? This is how Wolbachia survives. They live inside insect cells and can infect many organs of the host; there are many Wolbachia in the host eggs, but not in the sperm. In other words, only female hosts can transmit Wolbachia to their offspring, but not males . Therefore, an all-female population is most beneficial to the spread of Wolbachia.

Unlike humans, female wasps have twice as many chromosomes as males. During sexual reproduction, the reproductive cells undergo two rounds of division, eventually producing four haploid daughter cells, that is, each cell has only half the number of chromosomes. For wasps, unfertilized haploid eggs will develop into males, and normal fertilized eggs will develop into females. But scientists recently discovered that Wolbachia can somehow prevent the final step of division of wasp reproductive cells , resulting in the failure of haploid daughter cells to form. In the end, although they are still unfertilized egg cells, they have two sets of chromosomes and can develop into females.

The red area inside the insect body is where the Wolbachia bacteria live. Reference [5]

Scientists have also discovered that the method used by Wolbachia to cause collective sex change in its hosts was also "stolen" from others - they obtained sex-determining genes from other insects in ancient times and used them for their own purposes.

Scientists have long discovered the magic of Wolbachia and used it to control the number of insects , the most important of which is to eliminate mosquitoes that spread diseases such as malaria and dengue fever. After male mosquitoes are infected with Wolbachia, when they mate with uninfected females, they will not be able to produce offspring due to cytoplasmic incompatibility.

Gene mutations make good fathers

After a gene mutation, the somewhat unreliable fish father suddenly turned into a good father who works hard and is never complaining.

Male Cichlids are generally irresponsible fathers, while females will raise their children by mouth - hatching the eggs in their mouths and protecting their children until they grow up. The mouth-hatching process is very hard, and for up to 2 weeks, the mother cannot eat and loses weight quickly, which is a huge harm to their bodies.

The lower jaw of the female Astatotilapia burtoni protrudes when she is mouth-brooding | References [6]

Normal non-mouth-brooding males do not have a protruding chin | Reference [6]

In a recent study, scientists found that a male Cichlid burger had a protruding jaw, indicating that it was incubating eggs in its mouth. They studied the fish and found that it had a gene mutation that activated the male's "parenting attributes" . 30% of male fish carrying this gene will continue to incubate their eggs in their mouths for at least 1 hour, and some will become particularly conscientious and incubate their eggs in their mouths for a full 2 ​​weeks until the children can swim freely.

A genetically mutated male fish with a square, protruding lower jaw containing hatching eggs | Reference [6]

Scientists believe that both male and female fish have a neural circuit in their brains responsible for parenting, which gives them the natural ability to mouth-brood. However, when males receive pheromones released by females, the pheromones prevent the activation of this circuit, and males will not engage in mouth-brooding behavior. The genetic mutation that makes male fish good fathers causes changes in the pheromone receptors, so that the parenting neural circuit can be activated normally , allowing them to actively take the eggs into their mouths.

Author: Cat Tun

Editor: Mai Mai