American Bully Dog Breed Information and Characteristics

10 Small Animals That Are The Deadliest In The World

You might expect danger to come with claws or size, but the real threat often comes in small, quiet forms. These animals kill using venom, parasites, or pure stealth. And in some cases, just being in the wrong place at the wrong time can be fatal.

Here's a look at the small animals that cause the most damage, sometimes without anyone noticing.

Australian Box Jellyfish

Credit: Reddit

Box jellyfish move fast, with enough control to swim against currents. If you get tangled in their nearly invisible tentacles, the venom hits your heart, nervous system, and skin all at once. It shuts everything down quickly, often before help arrives. Since the 1800s, these animals have caused dozens of deaths in Australian waters.

Geography Cone Snail

Credit: flickr

It looks like the kind of shell you'd find on a windowsill, but this snail's got a hidden weapon. It shoots a venom-loaded tooth that shuts down muscles in seconds. And the bad news is that there is no antidote, so treatment is limited to keeping the person alive until the venom wears off.

Amazonian Giant Centipede

Credit: Getty Images

This centipede can grow up to a foot long and doesn't mind eating frogs, spiders, and even bats. Its poison works fast and leaves its prey unable to move. One tragic case involved a child in Venezuela who died after finding one in a soda can. They're tough and don't back away when confronted.

Mosquito

Credit: flickr

It's not surprising that mosquitoes are responsible for around 780,000 deaths every year. It's the viruses and parasites they carry that do the damage, with malaria being the deadliest, especially for young children. Other strains spread dengue, yellow fever, and Zika.

Freshwater Snails

Credit: flickr

They're slow, harmless-looking, and mostly ignored—but freshwater snails host parasites that kill over 200,000 people a year. The disease, schistosomiasis, begins when flukes in contaminated water get into your system through the skin. Once inside, they damage the bladder, intestines, and liver over time.

Saw-scaled Viper

Credit: flickr

Field workers often don't see the saw-scaled viper until they're already in pain. It's tiny, easy to miss, and doesn't give much warning. Its venom prevents blood from clotting, which leads to internal bleeding and can be fatal without treatment. The bite might not look serious at first, but symptoms build quickly.

Assassin Bug

Credit: flickr

True to its name, most people never even feel the bite of the assassin bug. It happens at night, usually on the face, while someone's asleep. After feeding, the bug leaves behind feces carrying Trypanosoma cruzi. As soon as it enters the bloodstream, this parasite causes long-term damage that may not show up for years.

Poison Dart Frog

Credit: flickr

Bright colors are usually a warning in nature, and this frog is no exception. The golden poison frog, in particular, carries enough toxin in its skin to kill multiple people. Contact with its skin is enough to trigger a fatal dose. Scientists believe this toxin builds up from eating venomous ants and mites found in its rainforest habitat.

Sydney Funnel-Web Spider

Credit: flickr

When heavy rain hits Sydney, these spiders start showing up in places you'd rather not find them—inside shoes, laundry baskets, or garages. They don't hold back when they bite. The venom targets the nervous system and can kill in as little as 15 minutes. But thanks to the antivenom developed in the 1980s, survival rates have improved.

Deathstalker Scorpion

Credit: flickr

Pain sets in fast with this scorpion. The sting burns sharply, and for children or the elderly, things can spiral into seizures or respiratory trouble. They live across parts of North Africa and the Middle East and come out at night, after hiding in cracks and loose debris all day long.

Tsetse Fly

Credit: Reddit

They look like regular houseflies, but tsetse flies carry far more risk. The fly spreads sleeping sickness, a parasitic illness that starts with fever and ends with brain damage if untreated. The disease is mainly fatal in late stages. In remote areas of sub-Saharan Africa, where health services are limited, a bite can go unnoticed until it's too late to fix.

Blue Sea Dragon

Credit: Reddit

Blue Sea Dragons float along the ocean surface and eat creatures like the Portuguese man o' war, storing that venom in their bodies. They don't attack—but they don't need to when people keep grabbing them. Their sting can cause intense pain, vomiting, and skin reactions. It's best to admire these creatures without ever getting too close.

Giant Silkworm Moth Caterpillar

Credit: Reddit

Brushing against one of these caterpillars can trigger a terrifying chain reaction. Its spines inject poison that causes internal bleeding by interfering with clotting. Victims don't feel much at first, but as the hours pass, symptoms get worse. Fatalities happen in Brazil each year, mostly from accidental contact during routine outdoor activity.

Brazilian Wandering Spider

Credit: Reddit

This spider moves through forest floors and even inside homes, searching for prey. One bite can take over your whole body in minutes. The toxin is extremely potent and has caused paralysis and suffocation in some victims. Even with treatment, it's not something anyone wants to deal with.

Ascaris Roundworm

Credit: Reddit

People swallow the eggs without realizing it, usually through food or water that's been contaminated. The Ascaris Roundworms eventually grow in the intestines and multiply. They can cause fevers, breathing trouble, or even block the digestive system. Around 2,500 people die each year from complications. Places without sewage systems see the worst cases.

11 Of The Smallest Mammals In The World

In the biological world, it seems as though bigger would be better. And while it's true that bigger often means stronger (therefore able to outcompete smaller species), it also means more resources are needed to sustain the extra mass, and you can just forget about being inconspicuous. Smaller animals are better at hiding, accessing tight spaces, climbing upon the flimsiest of branches, and occupying ecological niches that larger animals simply can't.

They're also cute. Who could resist a bat barely bigger than a human fingernail or a lemur that weighs a single ounce?

Discover 11 of the world's smallest mammals.

Etruscan Shrew Lies Van Rompaey on iNaturalist / Wikimedia Commons / CC BY 4.0 There are many tiny shrews, but this pipsqueak takes the cake as the smallest. The Etruscan shrew is the smallest mammal in the world by mass. On average, it weighs less than .14 ounces and has a body length of about 1.57 inches. For such a tiny animal, however, it has a huge appetite, typically eating about twice its own body weight every day. Pygmy Jerboa reptiles4all / Shutterstock Pygmy jerboas make up the rodent subfamily Cardiocraniinae and are the smallest rodents in the world. Their bodies start at two to three inches long, and their tails measure up to three inches. For their size, these minuscule mammals sure can jump. Jerboas have kangaroolike legs that allow them to leap distances far exceeding their body lengths, an adaptation that helps them move quickly over the vast, arid deserts in Northern Africa and Asia that they call home. Bumblebee Bat Merlin Tuttle's Bat Conservation The bumblebee bat, also known as Kitti's hog-nosed bat, is the world's smallest bat and the mammal with the smallest skull size. Weighing around .07 ounces (less than a penny) and with a length of 1.14 inches, it's so small that you might confuse one for a bumblebee if it went buzzing by your ear in the night. Unfortunately, its delicate size is also indicative of its biological status. The IUCN lists the animal as near threatened, and a few roosting populations are at risk of extinction due primarily to human activity. Mouse Lemur Michel VIARD / Getty Images These adorable creatures are the world's smallest primates, measuring up to 11 inches in length including their tails. The smallest species is the Madame Berthe's mouse lemur, which measures just about 3.5 to 4.3 inches in length and weighs only about an ounce. These softball-sized omnivores eat alone and mostly dine on "honeydew," a sugary byproduct of insect digestion. However, despite spending their foraging time alone, they do sleep with other mouse lemurs about half the time. Least Weasel Carol Hamilton / Getty Images This finicky, wise little weasel is the smallest species of the Carnivora order, making it the tiniest true carnivore in the world. North American least weasel males only reach seven inches, and the females grow to 5 inches. It weighs less than 1.5 ounces. It might be hard to imagine something so small being such a cunning hunter, but the lesser weasel is the worst nightmare of any small rodent it encounters. They exhibit a much bigger, more ferocious personality than their small size might suggest. Pygmy Possum TED MEAD / Getty Images Ranging in length between two and four inches and often weighing barely over .35 ounces, these mini marsupials are found hanging upside down in trees in Australia and New Guinea. IUCN lists one species, the Mountain Pygmy Possum, as critically endangered. This species has a limited habitat in the alpine areas of Australia. Ski resorts, road construction, and extensive bushfires have led to habitat destruction. The migratory Bogong moth makes up a significant portion of its diet and carries arsenic from pesticides in breeding grounds to the mountain. Scientists believe this is one factor leading to the decreasing population. African Pygmy Mouse PapaPics / Getty Images Mice are known for their small size, but the African pygmy mouse takes that trait to the extreme. Measuring 1.2 to 3.1 inches in length and weighing as little as .11 ounces, it is the world's smallest mouse. It is so petite that it typically stays hydrated by licking dew off tiny pebbles that it cleverly stacks in front of its burrow. Some people keep these elfin mice as entertaining pets. Owners must remain hands-off with them, though, as they are incredibly fragile. Pygmy Marmoset Jenhung Huang / Getty Images Occasionally referred to as the "pocket monkey," these adorable, curious animals native to the Amazon rainforest are the world's smallest monkeys. Pygmy marmosets rarely exhibit a length greater than about 5.12 inches and typically weigh 4.37 ounces. Their diet is as unique as their size. They use their sharp teeth and nails to gouge holes in trees and eat the sap, gum, and resins found inside. They also consume insects. Evolutionary biologists from the University of Salford released a study in February 2018 announcing the pygmy marmoset is actually two different species: one that lives in the north Amazon River area and the other in the south. Long-Tailed Planigale Alan Couch / Flickr / CC by 2.0 Native to Australia, long-tailed planigales are the world's smallest marsupials. They weigh less than .15 ounces and reach lengths averaging 2.32 inches, including the tail. Their small size and flattened heads allow planigales to squeeze into crevices and cracks any other mammal would find impossible. This ability enables them to find food and to hide from predators. Their pouches face toward the rear to keep it clean as they navigate these crevices. These fierce nocturnal carnivores hunt insects and even young mammals almost as large as themselves. American Shrew Mole Owen Borseth / Wikimedia Commons / CC BY-SA 4.0 The smallest species of mole in the world is the American shrew mole. This tiny mammal measures 4.72 inches long, including the tail, and weighs about .35 ounces. The American shrew mole doesn't even have external ears and has minuscule eyes that are almost invisible. Found in the U.S. Northwest and Canada's British Columbia, these adorable underground dwellers have smaller front paws than most other moles, a trait that is similar to a shrew. These moles travel in groups of 11 or more and spend more time above ground than other moles. Pen-Tailed Tree Shrew Paul J. Morris / Flickr / CC BY-SA 2.0 The smallest tree shrew in the world is the pen-tailed tree shrew, which can weigh as little as 1.41 ounces and measure barely more than 5 inches. They appear so closely related to primates that there is debate as to whether to class them as primates or insectivores. Instead, they belong to their own order: Scandentia. The pen-tailed tree shrew is the sole member of its genus. Sometimes known as a party animal, the primary diet of the nocturnal pen-tailed tree shrew is fermented alcohol from the bertam palm. It consumes amounts equivalent to 12 beers a day but never gets intoxicated. It also eats insects and small geckos. What Are the Ecological Advantages of Being Small? Being small can be a burden and a boon at the same time. While bigger animals tend to have more energy (thanks to faster metabolic rates), more speed, and greater fighting power against predators, small animals are better at tucking into tiny crevices and hiding. They don't need as many resources, so they don't have to do as much hunting. In some cases, smaller animals also have better reproductive efficiency and access to a wider variety of food. One study says small carnivores are better at responding to "environmental emergencies" than their larger counterparts.

Small Animals Acquire Genes From Bacteria That Can Produce Antibiotics

A group of small, freshwater animals protect themselves from infections using antibiotic recipes "stolen" from bacteria, according to new research by a team from the University of Oxford, the University of Stirling and the Marine Biological Laboratory (MBL), Woods Hole.

The tiny creatures are called bdelloid rotifers, which means 'crawling wheel-animals'. They have a head, mouth, gut, muscles and nerves like other animals, though they are smaller than a hair's breadth.

When these rotifers are exposed to fungal infection, the study found, they switch on hundreds of genes that they acquired from bacteria and other microbes. Some of these genes produce resistance weapons, such as antibiotics and other antimicrobial agents, in the rotifers. The team reports its findings this week in Nature Communications.

"When we translated the DNA code to see what the stolen genes were doing, we had a surprise," said lead study author Chris Wilson of University of Oxford. "The main genes were instructions for chemicals that we didn't think animals could make -- they looked like recipes for antibiotics."

Prior research found that rotifers have been picking up DNA from their surroundings for millions of years, but the new study is the first to discover them using these genes against diseases. No other animals are known to "steal" genes from microbes on such a large scale.

"These complex genes -- some of which aren't found in any other animals -- were acquired from bacteria but have undergone evolution in rotifers," said study co-author David Mark Welch, senior scientist and director of the Josephine Bay Paul Center at the Marine Biological Laboratory. "This raises the potential that rotifers are producing novel antimicrobials that may be less toxic to animals, including humans, than those we develop from bacteria and fungi."

Recipes for self-defense

Antibiotics are essential to modern healthcare, but most of them were not invented by scientists. Instead, they are produced naturally by fungi and bacteria in the wild, and humans can make artificial versions to use as medicine.

The new study suggests that rotifers might be doing something similar.

"These strange little animals have copied the DNA that tells microbes how to make antibiotics," explains Wilson. "We watched them using one of these genes against a disease caused by a fungus, and the animals that survived the infection were producing 10 times more of the chemical recipe than the ones that died, indicating that it helps to suppress the disease."

The scientists think that rotifers could give important clues in the hunt for drugs to treat human infections caused by bacteria or fungi.

Antibiotics are becoming less effective because the disease-causing microbes have evolved to become resistant and no longer respond to treatment. The World Health Organization recently sounded the alarm, warning in a June report of the "pressing need" to develop new antibiotics to counter the threat of resistance.

"The recipes the rotifers are using look different from known genes in microbes," said study author Reuben Nowell of the University of Stirling. "They're just as long and complicated, but parts of the DNA code have changed. We think the recipe has been altered by a process of evolution to make new and different chemicals in the rotifers. That's exciting because it might suggest ideas for future medicines."

The genes the rotifers acquired from bacteria encode an unusual class of enzymes that assemble amino acids into small molecules called non-ribosomal peptides.

"The next phase of this research should involve identification of multiple non-ribosomally synthesized peptides produced by bdelloid rotifers, and establishment of the conditions upon which the synthesis of these compounds can be induced," said study co-author Irina Arkhipova, senior scientist at the Marine Biological Laboratory.

One problem with developing new drugs is that many antibiotic chemicals made by bacteria and fungi are poisonous or have side-effects in animals. Only a few can be turned into treatments that clear harmful microbes from the human body.

If rotifers are already making similar chemicals in their own cells, they could lead the way to drugs that are safer to use in other animals, including people.

Why do rotifers acquire so many foreign genes?

A big question is why rotifers are the only animals that borrow these useful genes from microbes at such high rates.

"We think it might be linked with another strange fact about these rotifers," said Tim Barraclough, a study co-author from the University of Oxford. "Unlike other animals, we never see male rotifers. Rotifer mothers lay eggs that hatch into genetic copies of themselves, without needing sex or fertilization."

According to one theory, animals that copy themselves like this can become so similar that it starts to be unhealthy. "If one catches a disease, so will the rest," explained Barraclough. Because bdelloid rotifers don't have sex, which allows the parental genes to recombine in beneficial ways, the rotifer mother's genome is directly transferred to her offspring without introducing any new variation.

"If rotifers don't find a way to change their genes, they could go extinct. This might help explain why these rotifers have borrowed so many genes from other places, especially anything that helps them cope with infections," said Barraclough.

Nowell thinks there is much more to learn from rotifers and their stolen DNA "The rotifers were using hundreds of genes that aren't seen in other animals. The antibiotic recipes are exciting, and some other genes even look like they've been taken from plants. The findings are part of a growing story about how and why genes get moved between different kinds of life," he said.

---