A MEAL FOR EIGHT (LEGS): How spiders catch their food

Our planet is home to around 35,000-50,000 species of spider (the estimates vary), the vast majority of which spin webs made out of silk generated inside the spider’s body. As any arachnid expert will tell you, spiders weave their silky masterpieces primarily as a means of obtaining food. With strands stronger than the equivalent thickness of steel, spider webs are covered with sticky substances that ensnare their prey, trapping flies and even birds and snakes, ready for the web’s resident to deliver its venomous coup de grâce.

When an insect flying about and minding its own business collides with a web, which is often designed to be invisible until it is too late, the impact creates vibrations that alert the spider. Spiders have extra sensitive hairs on their legs, which are attuned to pick up the slightest movement coming from the web’s fabric.

However, arachnologists have not yet figured out how exactly the spider interprets the movement signals when its equivalent of a pizza delivery happens. In 2016, a team of scientists from the American state of Oregon decided to try and solve this puzzle by creating a web of their own.

Using nylon from parachutes, the team built a web that replicated a traditional ‘spoke’ layout, popularly associated with spiders. The strands of yarn were arranged radially and were held taut by a specially constructed machine with an aluminium frame, alongside an attachment resembling a spider placed centrally, as can be seen with garden spiders and orb weavers.

 

 

The vibrations caused by insects were reproduced with the help of a subwoofer-type speaker, and the spiral of the web was emulated with elastic cords. Ross Hatton, a member of the research team at Oregon State University, told GrandesMedios.com, the source of this story, of how realistic they made the web experiment, explaining that they used two different types of nylon rope, just as spiders use two different types of silk.

The artificial spider in the middle was calibrated to pick up vibrations from the speaker, even the slightest ones. As Hatton explained: “We started with the hypothesis that if you moved one of the radial lines slightly, the arachnid perceived that one moved more than the others,

“We also speculated, that the spider would go towards the line that undergoes a variation in its movement”

In other words, Hatton and his team expected the spider in real life to gravitate towards the line of silk from which the most movement was travelling from. However the result of the experiment was quite different from the team’s original hypothesis.

Far from being a simple case of only a single strand of the web notifying that it caught dinner, the team discovered that the cobweb gave off a complex pattern of vibrations, with some sections of the web being more sensitive than others. According to Hatton, at different frequencies of sound from the speaker, different web strands and layouts did not vibrate at all. Different parts and strands of the web vibrated only at certain frequencies and remained unresponsive at others.

These different frequencies of vibration are believed to help the spider identify what type of prey had crashed into its web, and perhaps also help it distinguish between live prey and inedible objects such as leaf fragments and debris. The study, which redrew the way people thought about how arachnids predate, was presented at the American Physical Society conference recently.

SOURCES:

Vijay Shah { विजय }, Twitter, Twitter Inc. https://twitter.com/VShah1984

Tecnología GM, Twitter, Twitter Inc. https://twitter.com/TecnologiaGM

“Cómo perciben las arañas a las víctimas que caen en su red” – GrandesMedios.com/Grandes Medios (6 April 2016) https://www.grandesmedios.com/asi-detectan-las-aranas-a-sus-victimas/

IMAGE CREDIT:

“Spider and web” – Dwight Sipler, Flickr (23 September 2009) https://www.flickr.com/photos/62528187@N00/3948508109/in/photolist-71V8U2-9ReV6c-aqKQGv-dpdK7M-5roAqX-5roEwn-5roBTv-DV9Eq-mYCVp-6Hu2Eb-5tj1DG-9oBvU-jG4wh-8JZa3e-a9A2a9-8WDwtQ-afhCqA-8yN4WL-5vSbKd-e2eBjU-aj8tGX-6QTWyn-4VgnTS-4Vc9mt-9aCUoX-4WYuxd-6bSLvd-51ycz-4rhGUq-31bfxS-316GzT-316xNt-316yCg-31b8K7-31b9dh-31b4TG-316z6p-316wva-31bbq9-31bdXs-31b3iw-31b64m-316EZD-31b7tU-316xwZ-31b8nG-31bdvo-31bcvw-316y1V-31baXE-316w2a

QUETZALCOATLUS: The flying dinosaur taller than a giraffe

(c) M. Witton via G. Trivedi

One of the largest pterosaurs, or flying reptiles, ever to flutter above the prehistoric skies was the Quetzalcoatlus. When resting, this giant of the clouds was taller than a modern-day giraffe, and considerably stronger. Tearing through the air at 130 kilometres per hour, Quetzalcoatlus was said to be fond of snacking on juvenile dinosaurs that strayed too far from their parents, while its smaller flying cousins, the pterodactyls, settled for fish. Its height met it could very easily look a giraffe in the eye, which may well be an unpleasant experience for the giraffe.

With a wing-span of around fifteen metres, half the length of a red London bus, Quetzalcoatlus may well have been the largest flying reptile, and indeed the largest flying animal full-stop, of all time. Compare Quetzalcoatlus’ over 30 feet wingspan with the world’s current largest flying bird, the Andean condor, whose span reaches about 10 feet, and you can readily appreciate how a flock of Quetzalcoatlus would have easily darkened the sky as they flew above you. Despite these astonishing bodily proportions, this pterosaur is considerably less well known outside the palaeontologist community. 

Quetzalcoatlus was named by its discoverers in honour of the Aztec feathered-serpent god Quetzalcoatl and is believed to have weighed close to 100 kilograms, necessitating its plane like wingspan. It was one of the last prehistoric reptile species known from the fossil record and disappeared during the great Cretaceous extinction of 65 million years ago, which most scientists believed was caused by a meteor or comet slamming into the Yucatan peninsula in now what is known as Mexico. Like other prehistoric reptiles, Quetzalcoatlus was a victim of the collapse of food chains that occurred in the millennia after this cataclysm. The species is said to have existed for around five million years before its demise. Its remains were first discovered by Douglas Lawson from the Maastrichtian Javelina Formation, a fossil bed located in Big Bend National Park of Texas, United States of America in 1971, although extensive interest in the wider community and the media did not take off until three decades later. Interestingly, the reptile’s remains were not found in fossilised marine sediments like others of its family, such as Pterodactyl, who would travel miles out to sea to hunt. Instead Lawson, who was a geology student at that time at the University of Texas-Austin, unearthed Quetzalcoatlus in the preserved remains of a river bed, which intrigued many palaeontologists trying to unmask the lifestyle and feeding habits of this unique and fearsome creature.

 

Like other pterosaurs, which also had phenomenal wingspans, Quetzalcoatlus could stay airborne due to the aerodynamics of its leathery wings, which worked rather like those of a glider aircraft, but also because its skeleton was lighter than that of land-based dinosaurs. The bones were spongy and contained large air pocket to help reduce drag while in the air, a trait shared with modern birds, who some scientist believe are descendants of smaller flying relatives of Quetzalcoatlus. They were estimated to glide at elevations of 10,000 to 15,000 feet with very minimal movement of its tarpaulin-like wings to save on expending energy. It controlled its flight movement by swivelling and adjusting its flexible wing tips and flexing the three fingers on the wing’s leading edge – along with subtle head movements to alter the flow of air over its body while soaring above the marshy swamps and grasslands of the prehistoric US and Canadian east coasts.

Even with its aerodynamics, flight take-off must have been a lot of work for Quetzalcoatlus. As it lived millions of years ago, there is no way of determining exactly how it took to the skies and glided (not actually fly, as modern birds generally do). An analysis of the animal’s remains suggest that it had to run across the ground for a distance before catching the wind and soaring up above, as a plane must use a runway in order to gain traction for flight. That analysis suggested that Quetzalcoatlus used all four of its limbs to help it get airborne. Its heavily-muscled front legs helped it vault into the air, while the back legs, which were more lean and spindly, played a secondary support role, and were more necessary for when the pterosaur was walking on land. Some hypothesise that Quetzalcoatlus made life easier on itself by launching itself off the tops of sheer cliffs and exploiting thermals of warm air rising from the sea’s surface.

Quetzalcoatlus was built not only for flight, but also for the kill – at least as some scientists surmise. With an elongated neck, rather like the giraffe in the artist’s impression above, the pterosaur could see for metres around as it searched for prey in the grasslands of prehistoric North America. Its bill was also extremely lengthy and robust and it had no problem with picking up smaller dinosaurs and devouring them. It even was believed to have used its jaws to impale some prey as it hunted them. Some scientists think that Quetzalcoatlus was rather more like a giant prehistoric vulture, using the bill to pick the rotting flesh from corpses or the abandoned kills of other carnivorous dinosaurs. A clip from a BBC documentary on flying reptiles shows that Quetzalcoatlus searched the ground for recently slaughtered dinosaurs and used its jaws to tear chunks from the carcass, but also capable of swallowing whole smaller live prey that dared to get in the way. Its discovery near an inland river also suggests that Quetzalcoatlus’ diet was not much different from its coastal relatives, and that it subsisted on a diet of molluscs and crustaceans, using its beak to probe the sands for burrowed prey much like the oystercatchers seen on our modern beaches. Alternatively it may have behaved as a seagull, fluttering just above the warm shallow seas of the late Cretaceous and plucking fish from just below the waves. No-one is one hundred per cent sure.

It was a member of the Azhdarchidae, a family of advanced toothless pterosaurs with unusually long, stiffened necks. Members of this branch of the reptilian kingdom occurred all over the Americas. Among palaeontologists and the wider prehistoric literature, it is known as a pterodactyloid pterosaur, due to the long ‘dactyls’ (fingers) it possessed. Its full Latin name was Queztalcoatlus northropi. In addition to the nod to the Aztec religion, the formal name also honours John Knudsen Northrop, the founder of the Northrop aviation company, who was interested in large tailless aircraft designs resembling Quetzalcoatlus. The earliest known pterosaurs lived about 220 million years ago in the Triassic period. They were the first vertebrates to achieve the use of daily flight, a legacy now evident in bats and birds. Quetzalcoatlus, if alive today, may well have made the skies more hazardous to human airborne traffic, but would have inspired awe and profound respect (and possibly a great deal of fear) among the ant-like humans that it saw milling across the ground from its vantage point thousands of metres in the skies above.

SOURCES:
Half-Eaten Mind, Twitter https://twitter.com/halfeatenmind
Gautam Trivedi ‏, Twitter https://twitter.com/Gotham3
“DINO FACT FILE – QUETZALCOATLUS, ABC/BBC, Australian Broadcasting Corporation http://www.abc.net.au/dinosaurs/fact_files/volcanic/quetzalcoatlus.htm
“Quetzalcoatlus” – Bob Strauss, About.com – Education – Dinosaurs http://dinosaurs.about.com/od/aviandinosaurs3/p/quetzalcoatlus.htm
“10 Facts About Quetzalcoatlus Everything You Need to Know About the World’s Biggest Pterosaur”  Bob Strauss, About.com – Education – Dinosaurs http://dinosaurs.about.com/od/otherprehistoriclife/a/Quetzalcoatlus-Facts.htm
“Quetzalcoatlus” – Wikia Dinopedia http://dinosaurs.wikia.com/wiki/Quetzalcoatlus
“QUETZALCOATLUS” – ZoomDinosaurs.com Dinosaur and Paleontology Dictionary, EnchantedLearning.com http://www.enchantedlearning.com/subjects/dinosaurs/dinos/Quetzalcoatlus.shtml
“Pterosaurs” – Big Bend National Park Texas, National Park Service/United States Department of the Interior http://www.nps.gov/bibe/naturescience/pterosaur.htm
IMAGE CREDIT:
Gautam Trivedi ‏, Twitter https://twitter.com/Gotham3
VIDEO CREDIT:
“Quetzalcoatlus – Flying monsters” – Paleo Studio (via ‘Flying Monsters’ series from the BBC), YouTube GB (29 December 2013) https://www.youtube.com/watch?v=sAQX6RbtjFg

 

OIL RIG SEA MONSTER: Experts solve two year old natural mystery

Biology experts have finally solved the mystery of an unknown giant sea ‘monster’ that was caught on video 5,000 ft (1.5 km) below a nearby oil rig in the Gulf of Mexico, according to British tabloid paper Metro.

In the six-and-a-half minute long video, which began as an inspection of the oil rig’s moorings, a strange gelatinous object is seen falling from the top of the cameraman’s view and then floats to the right of the screen. At first appearances it appears to resemble a large lump of seaweed or a plastic carrier bag, both of course unlikely due to their floating nature in bodies of water. The formless creature then disappears into the darkness of the Gulf’s waters. After a minute, the animal reappears and takes centre stage in front of the camera, revealing its entire form as though putting on a show. It then billows out, occupying nearly all the visible area. The mysterious organism remains in frame for more than five minutes before eventually slipping out of sight.

(c) Twitter via HNGN

Marine biologists pored over the footage, shot in 2012, and also consulted historical records and scientific files in their bid to determine the species of the monster, which had some similarities to jellyfish, but has no tentacles, fins or even a head.

Biologists from the Monterey Bay Aquarium Research Centre finally wrapped up the mystery by announcing that the Gulf monster was none other than a ‘placental jellyfish’, which they determined from observing the creature’s gonads in the video and the markings on its ‘sail’. The species can grow up to two feet wide and is normally found in the cooler waters of the north Atlantic, suggesting the Gulf monster may have been a stray washed into the area by strong currents.

The species is known by its Latin nameDeepstaria Reticulum” and is rarely sighted. This may also be the first time a jellyfish of this species has ever been caught on film. Also known as the “Deepstaria Enigmatica” it is “thought to be one of the largest invertebrate predators in the deep sea ecosystem,” according to the BBC. However its long, “paddle-like” arms do not have stinging tentacles like other jellyfish. The jellyfish has been seen by humans a total of 114 times since it was discovered by scientists 110 years ago, researchers told the BBC.

It belongs to the coelenterate (jellyfish) family Ulmaridae, and was first scientifically described in academic journals in 1967.  The bell of this species is thin and wide and resembles a translucent, undulating sheet or lava lamp as the animal moves. Its surface is similar in visual texture and colour to that of an onion’s skin. They are usually found in Antarctic and near-Antarctic seas but have been spotted in waters near the United Kingdom, at depths of 829 to 1830 metres.

SOURCES:
Metro, Facebook https://www.facebook.com/MetroUK
“Experts finally end two-year mystery of giant sea monster caught on camera” – Simon Farr, Metro/Associated Newspapers Limited (19 June 2014) http://metro.co.uk/2014/06/19/experts-finally-end-two-year-mystery-of-giant-sea-monster-caught-on-camera-4768748/
“Strange underwater sea creature caught on camera in the Gulf of Mexico (video)” – Annika Toernqvist, SFGate Science/Hearst Newspapers/Hearst Communications, Inc. (18 June 2014) http://blog.sfgate.com/science/2014/06/18/strange-underwater-sea-creature-caught-on-camera-in-the-gulf-of-mexico-video/#24361101=0
“Unknown Blob-Like Sea Creature Captured On Camera In Gulf Of Mexico (VIDEO)” –  Oulimata Ba, HNGN Headlines & Global News (18 June 2014) http://www.hngn.com/articles/34103/20140618/unknown-blob-sea-creature-filmed-underwater-camera-video.htm
“Deepstaria enigmatica” – Wikipedia/Wikimedia Foundation, Inc. http://en.wikipedia.org/wiki/Deepstaria_enigmatica
IMAGE CREDIT:
“Unknown Blob-Like Sea Creature Captured On Camera In Gulf Of Mexico (VIDEO)” –  Oulimata Ba, HNGN Headlines & Global News (18 June 2014) http://www.hngn.com/articles/34103/20140618/unknown-blob-sea-creature-filmed-underwater-camera-video.htm
VIDEO CREDIT:
“Massive Unidentified Sea Monster Caught on Video Off Oil-Rig” – Disclosure TV, YouTube GB (19 September 2013) https://www.youtube.com/watch?v=IJwGpZ38JHE