Chondrichthyes There are around 1, species in this class of fish. The species in this class have a flexible skeleton made of cartilage instead of bone.
The sharks are cold-blooded, they have always told us. And formally yes, because it is known that they equal the temperature of the waters where they swim.
Although it is also true that the hot muscles of sharks help them to dive and hunt more easily.
The analysis was made on a group of tiger sharks in Sydney, Australia, on which it was found that they prefer to swim in waters that are around 22 degrees Celsius in both winter and summer. Sharks, rays and chimeras belong to the group of cartilaginous fishes Class: They are a class of aquatic vertebrates that have a skeleton constituted mainly of cartilage.
For sharks the time to go hunting is at night, when their dams are calm the sharks patrol the reefs, they hunt at night, in the day they have little movement, it does not mean that they do not eat during the day, The favorite time for sharks is hunting at night.
So far most discovered sharks are carnivores, they eat fish, turtles, birds, dolphins, eat anything that moves, pieces of plastic have been found in their stomachs, they are often cannibal, they eat each other. Sharks have the intelligence of a washing machine: Can sharks get cancer? Despite their bad reputation, sharks could save our lives.
A team of scientists from the University of La Trobe, Australia, is pioneering its antibodies to improve treatments against malaria, cancer and rheumatoid arthritis in humans.
According to biologists Mick Foley and Stewart Nuttall at the BIO convention held in California, the antibodies of sharks are smaller, chemically more robust and biologically more stable than those of other animals. This makes them suitable candidates to be delivered orally instead of injected, since they survive without difficulty to the acidic conditions of the digestive system.
In addition, unlike other techniques that are being tried in the world that require first vaccination of the shark, the new method does not need previous immunization, which avoids a direct confrontation with the animal.
On the other hand, the researcher has verified that shark antibodies have a kind of elongated hook that naturally adheres to a protein of the malaria parasite, preventing it from invading the blood cells.
Now the challenge is to make small genetic modifications in the antibodies so that they adhere to the cancer cells or to certain inflammatory proteins with the same efficacy.
Shark senses From an evolution of the ears, sharks, like other fish, have a lateral line on each side of their body that allows them to detect pressure changes and movements in the water; like other elasmobranchs, they also have Lorenzini ampoules in their noses: The eyes of the sharks apparently have an excellent vision, enhancing the ability to see in low light conditions for example when hunting in caves or at night or at great depths thanks to the fact that behind the retina they have a tapetum lucidum.
However, recent studies indicate that their vision would be monochromatic to have a single type of cones or even lack them some species. The strongest sense of a shark is its smell.
It is a common myth that although sharks can smell blood miles away, think that if they smell it immediately they will find the person or animal that is bleeding. They only have an inner ear, a small hole that looks out over the skin near the eyes, they do not need external hearing because the sound in the water travels much faster than in the air.
Sharks are specialists in hearing bass sounds lower than hertzhear from 10 hertz infrasound to hertz. Sharks are unable to distinguish colors, according to a study conducted by Australian researchers that could benefit swimmers and surfers and, in addition, also the sharks themselves. If scientists are right, sharks see the world in gray tones, and only some may see green.
Scientists at the University of Western Australia used a technique called micro-spectrophotometry to analyze the retina cells of 17 shark species captured in Queensland and Western Australia. In all species, the most common type of light receptors were a type of very sensitive cells that allow night vision, but can not distinguish colors.
In addition, sharks lack cones, cells that respond individually to light at specific wavelengths. In human eyes, a variety of cells of this type helps us distinguish colors.
In 10 of the 17 shark species, these cones were not found at all. The cones do exist in the other seven species, but all were of a single type, sensitive to wavelengths around nanometers, corresponding to the green color.
This system of the retina allows sharks to differentiate shades of gray, but, most likely, not between colors, say the researchers. Monochromatic vision is very rare among terrestrial species, because the vision of color is a tool for survival in these habitats. However, it is less important in the marine environment, where colors are filtered in the depths and survival depends more on distinguishing contrasts, to determine if a shape in the penumbra is a prey or a predator.
Sharks tooth Most sharks do not chew what they eat, they swallow everything in large pieces. The teeth are arranged in rows, when one shark tooth is damaged or lost, it is replaced by another. Sharks can have up to 3, teeth in their life. Most sharks have 4 rows of teeth at any time inside their mouth.
The front row is the largest and does most of the work. Although some sharks can swim in river estuaries with freshwater and saltwater mixtures, and some may even use these areas as nurseries for small sharks, most of the time they live in ocean waters.
However, there are two species that are able to survive for a long time in fresh water, they have the physiological adaptations that allow them to do this. Although these sharks can survive for a long time in freshwater, there are no developing populations in rivers or freshwater lakes.
Sharks can drown when they are pulled back by the water they receive inside their gills. Sometimes, the fishermen kill the sharks by pulling them back for a while, when they are taken to the shore.The class Chondrichthyes comprises almost extant species ofcartilaginous fishes, encompassing skates, sharks, rays, andchimaeras.
The class contains 12 orders which are divided between 2 monophyletic subclasses, the Elasmobranchii (sharks, rays and skates) and Holocephali (chimaeras). Sharks are members of the Chondrichthyes class, which also includes rays and chimeras.
There are species of sharks currently recognized alive, distributed in 8 orders; There are aside, extinct orders. [tags: Papers] words (3 pages) $ [preview] Sharks - Sharks Although sharks belong to the class Chondrichtyes, there are many different types.
Sharks arose about million years ago and have remained virtually unchanged for the past 70 million years and still comprise a dominant group. Chondrichthyes is a class that contains the cartilaginous fishes: they are jawed vertebrates with paired fins, paired nares, scales, a heart with its chambers in series, and skeletons made of cartilage rather than bone.
The class is divided into two subclasses: Elasmobranchii and Holocephali. Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates.
The phylogenetic placement of Chondrichthyes: inferences from analysis ; Figure 3(a)) assuming different species trees. If we assume the conventional organismal tree, then two duplications and several gene losses can ex- Phylogenetic analysis of sharks.
These different households. of sharks are really different in the manner they look, live, and eat. They have different forms, sizes, colour, fives, dentitions, home ground, diet, personality, method of reproduction, and other properties.
Some types of shark are really rare and some are really common (like the dogfish shark).