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.
Researchers discover prehistoric shark species
on August 19, 2019 at 4:42 pm
Two South Carolina researchers have discovered a species of prehistoric shark, along with dozens of other fossils from prehistoric sea creatures.
Wildlife summit mulls trade rules to counter...
on August 18, 2019 at 10:23 am
Conservationists warned of "unprecedented" species declines Saturday as countries met in Geneva to tighten rules on trade in elephant ivory and products from other endangered animal and plants.
From tusks to tails, nations eye trade in...
on August 17, 2019 at 8:40 am
From guitars to traditional medicines and from tusk to tail, mankind's exploitation of the planet's fauna and flora is putting some of them at risk of extinction. Representatives of some 180 nations are meeting in Geneva to agree on protections for vulnerable species, taking up issues including the trade in ivory and the demand for shark fin soup.
Study describes the Trans-Saharan Seaway in Mali,...
on August 16, 2019 at 1:24 pm
Leif Tapanila, Idaho State University geosciences professor and director of the Idaho Museum of Natural History, is a co-author on a scientific paper published this summer in the Bulletin of the American Museum of Natural History that describes the Trans-Saharan Seaway in Mali, Africa, and the strange creatures that existed there 50 to 100 million years ago.
Global meet to mull trade rules to protect...
on August 16, 2019 at 6:50 am
Specialists will meet in Geneva from Saturday to try to tighten rules on trade in elephant ivory, rhino horns and other endangered animal and plant species amid growing alarm over accelerating extinctions.
Countries push to protect sharks, rays
on August 15, 2019 at 8:50 pm
Dozens of countries will push at a global meeting for regulations on trade in 18 types of shark and ray, with conservationists warning Thursday of looming extinction for many species.
These sharks use unique molecules to glow green
on August 8, 2019 at 3:30 pm
In the depths of the sea, certain shark species transform the ocean's blue light into a bright green color that only other sharks can see—but how they biofluoresce has previously been unclear. In a study publishing August 8 in the journal iScience, researchers have identified what's responsible for the sharks' bright green hue: a previously unknown family of small-molecule metabolites. Not only is this mechanism of biofluorescence different from how most marine creatures glow, but it may […]
Research cruise off California finds life lacking...
on August 7, 2019 at 3:40 pm
In parts of the California Current this summer, the ocean was clear, azure and almost empty.
Blue sharks ride deep-swirling currents to the...
on August 7, 2019 at 1:20 pm
When you're hungry, wouldn't it be nice to just slip into a tunnel that rushes you off to a grand buffet? It sounds like something Elon Musk might dream up, but it turns out, certain species of sharks appear to have this luxury.
Industrial fishing behind plummeting shark numbers
on August 6, 2019 at 6:00 pm
A team of researchers, led by international conservation charity ZSL (Zoological Society of London), has discovered that sharks are much rarer in habitats nearer large human populations and fish markets. The team also found that the average body size of sharks and other marine predators fell dramatically in these areas, where sharks are caught and killed intensively for their meat and fins.