Senses of the shark
Smell
The shape of the hammerhead shark's head may enhance olfaction by spacing the nostrils further apart.Sharks have keen olfactory senses, located in the short duct (which is not fused, unlike bony fish) between the anterior and posterior nasal openings, with some species able to detect as little as one part per million of blood in seawater. They are more attracted to the chemicals found in the guts of many species, and as a result often linger near or in sewage outfalls. Some species, such as nurse sharks, have external barbels that greatly increase their ability to sense prey.
Hearing
Although it is hard to test sharks' hearing, they may have a sharp sense of hearing and can possibly hear prey many miles away.[27] A small opening on each side of their heads (not to be confused with the spiracle) leads directly into the inner ear through a thin channel. The lateral line shows a similar arrangement, which is open to the environment via a series of openings called lateral line pores. This is a reminder of the common origin of these two vibration- and sound-detecting organs that are grouped together as the acoustico-lateralis system. In bony fish and tetrapods the external opening into the inner ear has been lost.
Speed
In general, sharks swim at an average speed of 8 kilometres per hour (5.0 mph) but when feeding or attacking, the average shark can reach speeds upwards of 19 kilometres per hour.The shortfin mako shark, the fastest shark and one of the fastest fish, can burst up to 50 kilometres per hour (31 mph). The great white shark is also capable of bursts of speed. These exceptions may be due to the warm-blooded, or homeothermic, nature of these sharks' physiology.
Sleep
Some sharks can lie on the bottom while actively pumping water over their gills, but their eyes remain open and actively follow divers. When a shark is resting, it does not use its nares, but rather its spiracles. If a shark tried to use its nares while resting on the ocean floor, it would be sucking up sand rather than water. Many scientists believe this is one of the reasons sharks have spiracles. The spiny dogfish's spinal cord rather than its brain, coordinates swimming, so it is possible for spiny dogfish to continue to swim while sleeping. It is also possible that sharks sleep in a manner similar to dolphins,[50] one cerebral hemisphere at a time, thus maintaining some consciousness and cerebral activity at all times.
Distribution and habitat
Sharks are found in all seas. They generally do not live in freshwater, with a few exceptions such as the bull shark and the river shark which can swim both in seawater and freshwater. Sharks are common down to depths of 2,000 metres (7,000 ft), and some live even deeper, but they are almost entirely absent below 3,000 metres (10,000 ft). The deepest confirmed report of a shark is a Portuguese dogfish at 3,700 metres (12,100 ft).
My reflection base on the researches:
Shark is a great animal,after done so many researches on sharks, I realised that sharks does not like what people though cruel and evil,in fact that sharks are a great and amazing animal.People fear sharks,however, people also hunt sharks because their delicious shark fin and shark oil.shark skin also are a kind of good material for making handbags and shoes.
in fact, now days the number of sharks are decearsing very fast.Every year more than 100 million shrks were killed by peoples.now days, prople hunting sharks not for protect thenselves but to hunt for themselves.so if we do not protect sharks from now, soon,shark will be another animal which disaper from our earth.
URL:http://en.wikipedia.org/wiki/Shark#Conservation
21 Mar 2010
16 Mar 2010
Sharks
The research base on sharks habit:
Shark is found mostly in temperate seas throughout the world's oceans. It makes infrequent visits to cold waters and has been recorded off Alaska and Canada.
Great whites can be found along the coastlines of South Africa, Australia, New Zealand, California to Alaska, the east coast of USA and the Gulf coast, Hawaii, most of South America, the Mediterranean Sea, West Africa to Scandinavia, Japan and the eastern coastline of China and southern Russia.
The white shark lives mainly in the upper part of the water column, near the shore. However, it ranges from the surf line to well offshore and from the surface and to depths of over 250m.This shark commonly patrols small coastal islands inhabited by pinnipeds ,offshore reefs, banks and rocky headlands where there is deepwater close to shore. The white shark usually cruises either just off the bottom or near the surface.
Movement
Although information about the white shark's movements is limited by its rarity, some information has been gathered through tag-and-release programs in the United States, South Africa and Australia. These studies reveal that the white shark is capable of making movements on localised, regional and intercontinental scales. Generally, larger individuals undertake long journeys across the great oceans.
The great white is also capable of short, high-speed pursuits and even launching itself clear from the water (breaching). They are propelled through the water by their powerful tails, and they use their fins for balance. Sharks swim constantly, otherwise they will sink as they don't have a buoyant swim bladder like other fish.
my reflection:
After, I done the research base on sharks, I had understand and learned many things, people always thought that sharks are cruel and fear, however, this is not true.We got this opinion from some movies and story books,but not much people know that sharks actually is a kine of animal which very important to the ocean.Sharks help to control the population of animals in ocean,sharks will ear up the animal which had a great amount of population.
Many people fear sharks,because they through sharks will attack human,or even take human as their food,however, this was not true.Shark only attack other kind animal when they were hungry or they felt danger come from those kind of animals,so when we if found sharks near us when we in the sea, do not attack them or chest them away, the best way was to swim away quietly and when shark attacking you, the best way was use your hand and arm protect your head and quickly swim away.
Shark is found mostly in temperate seas throughout the world's oceans. It makes infrequent visits to cold waters and has been recorded off Alaska and Canada.
Great whites can be found along the coastlines of South Africa, Australia, New Zealand, California to Alaska, the east coast of USA and the Gulf coast, Hawaii, most of South America, the Mediterranean Sea, West Africa to Scandinavia, Japan and the eastern coastline of China and southern Russia.
The white shark lives mainly in the upper part of the water column, near the shore. However, it ranges from the surf line to well offshore and from the surface and to depths of over 250m.This shark commonly patrols small coastal islands inhabited by pinnipeds ,offshore reefs, banks and rocky headlands where there is deepwater close to shore. The white shark usually cruises either just off the bottom or near the surface.
Movement
Although information about the white shark's movements is limited by its rarity, some information has been gathered through tag-and-release programs in the United States, South Africa and Australia. These studies reveal that the white shark is capable of making movements on localised, regional and intercontinental scales. Generally, larger individuals undertake long journeys across the great oceans.
The great white is also capable of short, high-speed pursuits and even launching itself clear from the water (breaching). They are propelled through the water by their powerful tails, and they use their fins for balance. Sharks swim constantly, otherwise they will sink as they don't have a buoyant swim bladder like other fish.
my reflection:
After, I done the research base on sharks, I had understand and learned many things, people always thought that sharks are cruel and fear, however, this is not true.We got this opinion from some movies and story books,but not much people know that sharks actually is a kine of animal which very important to the ocean.Sharks help to control the population of animals in ocean,sharks will ear up the animal which had a great amount of population.
Many people fear sharks,because they through sharks will attack human,or even take human as their food,however, this was not true.Shark only attack other kind animal when they were hungry or they felt danger come from those kind of animals,so when we if found sharks near us when we in the sea, do not attack them or chest them away, the best way was to swim away quietly and when shark attacking you, the best way was use your hand and arm protect your head and quickly swim away.
9 Mar 2010
journal:sharks
1. base on what I understanding about sharks:
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago, before the time of the dinosaurs.
Since that time, sharks have diversified into 440 species, ranging in size from the small dwarf lanternshark, Etmopterus perryi, a deep sea species of only 17 centimetres (7 in) in length, to the whale shark, Rhincodon typus, the largest fish, which reaches approximately 12 metres (39 ft).
2.what is the purpose for people killing sharks?
"Shark fin soup" is a Chinese soup that has been a popular item of Chinese cuisine since the Ming Dynasty, usually served at special occasions such as weddings and banquets, or as a luxury item in Chinese culture.
There is controversy over the practice of shark finning which is used to source the signature ingredient for the soup. Consumption of shark fin soup has risen dramatically with the middle class becoming more affluent. Animal rights activists and environmentalists have called the practice brutal[3], and it is also named as a primary contributing factor in the global decline of many shark species.
China's growing economy has resulted in a large increase in demand for shark fins; combined with the importance of this top predator in oceanic ecosystems, has exacerbated problems the practice perpetuates.
3. Sustainability
See also: Shark finning
Over 100 million sharks are killed every year, a portion of which due to the demand for shark fin soup. Major declines in shark populations have been recorded in recent years—some species have been depleted by over 90% over the past 20–30 years with a population decline of 70% not being unusual. Only a small amount of the shark is actually kept. This is done is a process called finning where the fins of the shark is cut from living sharks. After the fins have been cut off, the remainder of the fish which is often still-living, is thrown back into the sea.[28] When returned to the ocean, the finless shark is unable to swim and sinks to the ocean bottom and dies a slow death.
The 2007 documentary Sharkwater exposes the abuse in shark-finning industry and the damage it is causing to the ocean's ecosystems. It also uncovers government corruption supporting the industry.
(parts of information come from Wikipedia)
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago, before the time of the dinosaurs.
Since that time, sharks have diversified into 440 species, ranging in size from the small dwarf lanternshark, Etmopterus perryi, a deep sea species of only 17 centimetres (7 in) in length, to the whale shark, Rhincodon typus, the largest fish, which reaches approximately 12 metres (39 ft).
2.what is the purpose for people killing sharks?
"Shark fin soup" is a Chinese soup that has been a popular item of Chinese cuisine since the Ming Dynasty, usually served at special occasions such as weddings and banquets, or as a luxury item in Chinese culture.
There is controversy over the practice of shark finning which is used to source the signature ingredient for the soup. Consumption of shark fin soup has risen dramatically with the middle class becoming more affluent. Animal rights activists and environmentalists have called the practice brutal[3], and it is also named as a primary contributing factor in the global decline of many shark species.
China's growing economy has resulted in a large increase in demand for shark fins; combined with the importance of this top predator in oceanic ecosystems, has exacerbated problems the practice perpetuates.
3. Sustainability
See also: Shark finning
Over 100 million sharks are killed every year, a portion of which due to the demand for shark fin soup. Major declines in shark populations have been recorded in recent years—some species have been depleted by over 90% over the past 20–30 years with a population decline of 70% not being unusual. Only a small amount of the shark is actually kept. This is done is a process called finning where the fins of the shark is cut from living sharks. After the fins have been cut off, the remainder of the fish which is often still-living, is thrown back into the sea.[28] When returned to the ocean, the finless shark is unable to swim and sinks to the ocean bottom and dies a slow death.
The 2007 documentary Sharkwater exposes the abuse in shark-finning industry and the damage it is causing to the ocean's ecosystems. It also uncovers government corruption supporting the industry.
(parts of information come from Wikipedia)
6 Mar 2010
journal: understanding sungei buloh
after read the informations about sungei buloh,those are my understanding about the
sungei buloh
The Sungei Buloh Wetland Reserve is a nature reserve located in the Northwest area of Singapore. It is the first wetlands reserve to be gazetted in Singapore in the year 2002, and its global importance as a stop-over point for migratory birds was also recognised by the Wetlands International's inclusion of the reserve into the East Asian Australasian Shorebird Site Network. The reserve, with an area of 130 hectares, was listed as an ASEAN Heritage Park in 2003.
Since its inception, the Reserve had provided nature education programs as well as a volunteer guide programme for schools and the general public. These include the SUN Club programme which are meant for students with special needs, mentorship programmes for secondary school students and Young Naturalists Programme. Many such programmes were collaboration efforts with partners such as British Council and the Ministry of Education. The Reserve distributes education materials such as workshops, guidebook and a triannual magazine, 'Wetlands' to further enrich the students and public. Each year, the nature reserve receives more than 400 organised school visits.
On 25 August 2007, a wireless learning trail was launched at Sungei Buloh Nature Reserve. The new initiative which integrates technology with nature education was a partnership amongst Ministry of Education (MOE), Infocomm Development Authority of Singapore (IDA) and a private sector company iCELL Network. Sungei Buloh Nature Reserve was the first park in Singapore to engage such a learning method.
sungei buloh
The Sungei Buloh Wetland Reserve is a nature reserve located in the Northwest area of Singapore. It is the first wetlands reserve to be gazetted in Singapore in the year 2002, and its global importance as a stop-over point for migratory birds was also recognised by the Wetlands International's inclusion of the reserve into the East Asian Australasian Shorebird Site Network. The reserve, with an area of 130 hectares, was listed as an ASEAN Heritage Park in 2003.
Since its inception, the Reserve had provided nature education programs as well as a volunteer guide programme for schools and the general public. These include the SUN Club programme which are meant for students with special needs, mentorship programmes for secondary school students and Young Naturalists Programme. Many such programmes were collaboration efforts with partners such as British Council and the Ministry of Education. The Reserve distributes education materials such as workshops, guidebook and a triannual magazine, 'Wetlands' to further enrich the students and public. Each year, the nature reserve receives more than 400 organised school visits.
On 25 August 2007, a wireless learning trail was launched at Sungei Buloh Nature Reserve. The new initiative which integrates technology with nature education was a partnership amongst Ministry of Education (MOE), Infocomm Development Authority of Singapore (IDA) and a private sector company iCELL Network. Sungei Buloh Nature Reserve was the first park in Singapore to engage such a learning method.
Subscribe to:
Posts (Atom)