Note: These are 360° videos — press and hold to explore them!
Tree of Life
Plant Flower, Tree
Invertebrate Octopus, Ant, Bee, Butterfly, Spider, Lobster
Vertebrate Fish, Seahorse, Ray, Shark, Frog, Turtle, Tortoise, Dinosaur
Bird, Ostrich, Owl, Crow, Parrot
Mammal Bat, Rabbit, Giraffe, Camel, Horse, Elephant, Mammoth
Whale, Dolphin, Walrus, Seal, Polar Bear, Bear, Cat, Tiger, Lion, Dog, Wolf
Monkey, Chimpanzee, Human
These are organized by a classification scheme developed exclusively for Cosma. More…
shark : any of numerous mostly marine cartilaginous fishes of medium to large size that have a fusiform body, lateral branchial clefts, and a tough usually dull gray skin roughened by minute tubercles and are typically active predators sometimes dangerous to humans — Webster
Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the rays. However, the term “shark” has also been used for extinct members of the subclass Elasmobranchii outside the Selachimorpha, such as Cladoselache and Xenacanthus, as well as other Chondrichthyes such as the holocephalid eugenedontidans. Under this broader definition, the earliest known sharks date back to more than 420 million years ago. Acanthodians are often referred to as “spiny sharks”; though they are not part of Chondrichthyes proper, they are a paraphyletic assemblage leading to cartilaginous fish as a whole.
Since then, sharks have diversified into over 500 species. They range in size from the small dwarf lanternshark (Etmopterus perryi), a deep sea species of only 17 centimetres (6.7 in) in length, to the whale shark (Rhincodon typus), the largest fish in the world, which reaches approximately 12 metres (40 ft) in length. Sharks are found in all seas and are common to depths of 2,000 metres (6,600 ft). They generally do not live in freshwater although there are a few known exceptions, such as the bull shark and the river shark, which can survive and be found in both seawater and freshwater. Sharks have a covering of dermal denticles that protects their skin from damage and parasites in addition to improving their fluid dynamics. They have numerous sets of replaceable teeth.
Well-known species such as the great white shark, tiger shark, blue shark, mako shark, thresher shark, and the hammerhead shark are apex predators—organisms at the top of their underwater food chain. Many shark populations are threatened by human activities. — Wikipedia
10 Best Places to Swim With Sharks (Professional Association of Diving Instructors, Condé Nast Traveler)
25 Best Destinations for Sharks and Adventure (Travis Marshall, Scuba Diving)
Shark Diving Tips and Advice (Shart Trust)
10 Shark Diving Tips (Dive Magazine)
Phys.org - latest science and technology news stories Phys.org internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine.
Size is everything, ecologist finds
on May 20, 2019 at 4:01 pm
Natural ecosystems are as vulnerable as they are diverse. Environmental changes such as climate change, pollution or the spread of alien species can easily throw an ecosystem off balance. Researchers are therefore investigating how susceptible ecosystems are to disruption. But in their search for answers they face the problem that the complex network of relationships includes innumerable interactions, which are virtually impossible to record comprehensively and convert into measurable data. […]
Study dives deep into saving endangered shark
on May 17, 2019 at 12:16 pm
Mackerel sharks are large, fast-swimming apex predators that include Hollywood heavy-hitters like great whites (Jaws), mako (Deep Blue Sea) and the now-extinct Megalodon (The Meg). One of the smallest mackerel sharks is the porbeagle—on average less than two metres long—and it's one of the most critically endangered species of shark, too. […]
Tiger sharks revealed as lazy predators
on May 15, 2019 at 1:10 pm
One of the ocean's most feared predators – the tiger shark—has been revealed as a relaxed and sometimes lazy hunter by scientists studying their behaviour. […]
How is climate change affecting fishes? There are...
on May 14, 2019 at 2:10 pm
Climate change affects all life on Earth, but it poses unique challenges for aquatic species. For example, as water warms it holds less dissolved oxygen than cooler water. As a result, the world's oceans, coastal seas, estuaries, rivers and lakes are undergoing a process known as "deoxygenation." […]
15-foot great white shark is being tracked off...
on May 13, 2019 at 11:00 pm
Shark trackers say a 15-foot, 2,137-pound great white shark is traveling up the Carolinas coast on a path toward the Outer Banks. […]
Google I/O: Cheaper Pixel 3a, Android Q,...
on May 9, 2019 at 9:10 am
Even after all these years, the first thing that likely comes to mind when you think Google is search. Google has long been about way more than that, of course, and the annual Google I/O developer conference, now underway in Mountain View, California, is where the Alphabet-subsidiary previews new hardware, software and other products. […]
Thai bay made famous in 'The Beach' to be shut...
on May 9, 2019 at 8:43 am
The closure of the glittering Thai bay made famous by the movie "The Beach" has been extended for another two years to allow a full recovery of its corals and wildlife, an official said Thursday, drawing a sharp rebuke from the tourism industry. […]
Basking sharks are back on West Coast, and...
on May 8, 2019 at 2:54 pm
Ryan Lawler saw the dorsal fin in the distance, swaying slowly side to side, and assumed it was a great white shark. As his boat got closer, he saw the massive fish's snout sticking out of the water, its mouth wide open. […]
Researchers discover a trigger for directed cell...
on May 8, 2019 at 12:25 pm
When an individual cell is placed on a level surface, it does not keep still, but starts moving. This phenomenon was observed by the British cell biologist Michael Abercrombie as long ago as 1967. Since then, researchers have been thriving to understand how cells accomplish this feat. This much is known: Cells form so-called lamellipodia—cellular protrusions that continuously grow and contract—to propel themselves toward signaling cues such as chemical attractants produced and […]
UN report: Humans accelerating extinction of...
on May 6, 2019 at 3:01 pm
People are putting nature in more trouble now than at any other time in human history, with extinction looming over 1 million species of plants and animals, scientists said Monday. […]