Spider Hunting Strategies

Stabbing, crushing, spitting and seducing are some of the more unusual, gruesome and clever ways spiders catch and kill their prey.

Though these predators are best known for ensnaring their food in sticky webs and paralyzing them with venom, this is only one of many ways the world's 40,000 or so known spider species catch a meal.

Spiders are found everywhere from rain forests to deserts, and can even be found in tide pools along the coast. What they eat, and how they capture it, is just as varied as where they live. Spiders catch and consume insects, other spiders and even small animals including snakes and birds.

The above fishing spider waits near water, typically with their front legs resting on the surface to detect the vibrations of potential prey. Once an animal comes close enough, fishing spiders strike with their fangs.

Net-casting spiders, below, hang upside down on a scaffold of silk, spin fuzzy webs they hold tight between two of their front legs and wait for insects. If a flying insect comes within reach, net-casting spiders will sweep their net toward the prey, snagging it out of the air. If an insect passes underneath them, the spiders drop down and spread a net over the victim.

To read more, see the original article here.

Why Male Spiders Are So Small

Male spiders may be tiny compared to their female counterparts in part because it makes it easier for them to get around and spread their genes.

Scientists studied different spiders’ aptitude for bridging — sending out strands of thread that get carried by the wind to another spot, and then crawling across — by placing them in a wind tunnel and watching them move around. They discovered that smaller spiders made bridges more often, and that the technique was more common in spiders with a pronounced difference in size between the sexes.

In species where bridging is a very common mode of locomotion, small males, by being more efficient bridge builders, will enjoy more mating opportunities and thus will be better at competition to reach receptive females.  This may lead to a selective pressure for smaller size.

The picture on the right is of a female and male orb-weaver spider.

Original article here.

Preserved 165-million Year Old Spider Fossible Found

Scientists have unearthed an almost perfectly preserved spider fossil in China dating back to the middle Jurassic era, 165 million years ago.

The fossils were found at a site called Daohugou in Northern China that is filled with fossilized salamanders, small primitive mammals, insects, and water crustaceans. During the Jurassic era, the fossil bed was part of a lake in a volcanic region.

Spider fossils from this period are rare, because the arachnids’ soft bodies don’t preserve well. The pristine fossil pictured in these photos was probably created when the spider was trapped in volcanic ash. The ultra-fine clay particles squashed the spider without breaking up the animals’ delicate cuticle as more coarse sediment would.

Original article here.

The Spider Awards: Arachnid Hall of Fame

Below are several examples of spiders from Wired's Spider Awards: Arachnid Hall of Fame. Read the article to learn more about the various species. Example "awards" for spiders include: largest, smallest, deadliest, cutest, nicest, sneakiest, weirdest, snobbiest, cuddliest and busiest.



















Original article here.

Giant Orb Spider Discovered

Scientists have found the world’s largest species of golden orb-weaver spider in the tropics of Africa and Madagascar. The discovery marks the first identification of a new Nephila spider since 1879.

Females of the new species, Nephila komaci, measure 4 to 5 inches in diameter, while the male spiders stay petite at less than a quarter of their mate’s size. So far, only a handful of these enormous arachnids have been found in the world. Its only definite habitat is a sand forest in Tembe Elephant Park in KwaZulu-Natal.

Like all Nephila spiders, females of the new species spin huge webs of golden silk, often more than 3 feet in diameter. In the report of the discovery of this rare spider, the researchers also addressed the evolution of the dramatic size difference between male and female orb-weavers.

By mapping out the evolutionary tree of all known orb-weaver species, the scientists discovered that as the spiders evolved, females got bigger and bigger, while males stayed roughly the same size.

It is good for females to be big, because they can lay so many more eggs. In addition, large size probably helps females avoid being eaten by predators. Males, on the other hand, are better off staying small and reaching sexual maturity at a young age. Because males spend most of their time underground, hunting for a mate is one of the most dangerous activities they undertake.

Original article here.

Ancient spiders yield 3D secrets

Ancient fossilized, spider-like species have been imaged in 3D using thousands of X-ray scans and imaging software.

The two species, Cryptomartus hindi and Eophrynus prestvicii, lived 300 million years ago but are closely related to modern spiders.

The 3D images show that C. hindi grasped at prey with its front legs and E. prestivicii had defensive spikes on its back.

The 3D images were obtained by using a computed tomography scanner - a device that can take X-ray images from many angles.

Some 3,000 images of each fossil were obtained, and a custom software package developed at Imperial College London was used to assemble the images into a single, detailed, 3D virtual model of the creatures.

The researchers suggest that the animal probably was an "ambush predator" like the modern-day crab spider, lying in wait for prey to come close.

Another finding from the models is that E. prestivicii had hard spikes along its back, probably as a defensive measure making it less palatable to the amphibians that would have hunted it.

Click on the below images to be taken the web page with videos of the 3D renderings:





Original articles here and here.

Deadly Creatures

Below are several examples from this gallery of Australia's deadliest creatures.

The cone snail is an underwater snail with a tooth-like stinger which acts like a harpoon. It has enough venom to kill a human as it paralyses the respiratory muscles. The cone snail's shell is pretty and colourful, so tourists often unknowingly pick them up:



The most venomous fish in the world, the stonefish is not aggressive, however its proximity to shores and ability to camouflage itself in coral makes it easy for people to accidentally touch or brush against. It has 13 dangerous spines and a dorsal fin, and when humans are stung it causes death to tissues:



The funnel-web spider sets up a trip-wire so it knows when prey is passing by, and its venom can kill a human in 15 minutes:



The blue-ringed octopus changes from a muddy orange colour to a vibrant blue when it strikes. It has venom 10,000 times more toxic than cyanide and can kill in 90 minutes. The size of a golf ball, its beak can penetrate a wetsuit:



See the full gallery here.

Jumping Spider Mating Ritual

Below is an interesing video of a male jumping spider (salticidae). He taps, scrapes, turns and twists, and makes interesting noises (be sure to turn your volume up):

World's Oldest Spider Web

The world's oldest spider web has been found in a piece of amber on the south coast of England, scientists announced recently.

Until the new find, the oldest known amber containing ancient animals dated to the Middle Cretaceous period, about 120 million years ago. But the new find has pushed back the "amber window" to 140 million years ago, during the heyday of the dinosaurs.

Assassin Spiders

Researchers working in Madagascar discovered nine species of "assassin spiders" — a family of arachnids that feast on other eight-leggers — during a four-year survey of the island nation's forests. They have a fearsome appearance, poisonous bite, and deadly hunting skills.

The spiders stab their prey with their giant jaws, which are barbed at the ends with venomous fangs. To be able to lift their outsized jaws, the assassins evolved elongated necks, giving the spiders a unique ability to strike from a distance. The assassin spiders are only an eighth of an inch long and are harmless to humans.

Original article here.