Explore Deeper......

The largest and most powerful fish in the prehistoric times was most probably the Megalodon which mean "big tooth" in Greek. It was a giant shark that lived approximately 25 to 1.5 million years ago, and was a super-predator. Its maximum size is theorized by experts to be around 20.3 metres in length and 114 short tons in weight. This makes it the largest shark in vertebrate history and also one of the biggest hyper-carnivorous predators ever known. Experiments conducted by scientists have shown that its bite force is 5 times greater than that of a T.Rex! Its teeth are morphologically similar to great white shark teeth but are more robust. They are more regularly serrated, much larger and exceeding 18 cm in slant height. However, it is not yet clear why C. megalodon became extinct after millions of years of dominance. Several factors like climatic upheavals, changes in the food chain, cannibalism and competition may have been involved.

Interaction with Humans

Shark fishery

Due to commercial and recreational fishing, it is estimated that 100 million sharks are killed by people every year. Sharks are a common seafood in many places and they are often killed for shark fin soup. Finning usually involves removing the fin of a shark with a hot metal blade. Fishermen capture live sharks, fin them and dump the finless animal back into the water. The now immobile shark soon dies from suffocation or predators. Shark finning has become a major trade within black markets all over the world and poachers illegally fin millions of sharks a year. The shark fin trade has become a major problem and has gained international attention. Conservationists now have campaigned to make finning illegal in the USA.




Shark attacks
A shark attack is an attack on humans by sharks. Every year, a number of people are attacked by sharks although death is quite unusual. Despite the relative rarity of shark attacks, the fear of sharks is a common phenomenon. It has been fueled by some occasional instances of attacks.

Habitat and Conservation

Habitat

Sharks are found in all seas. They generally do not live in freshwater. Sharks are common down to depths of 2,000 metres and some live even deeper, but they are almost entirely absent below 3,000 metres. However, the deepest confirmed report of a shark is a Portuguese dogfish at 3,700 metres.

Conservation

The majority of shark fisheries around the globe have little monitoring or management. The rise in demand for shark products increases pressure on fisheries. Stocks decline and collapse because it is difficult for sharks to breed rapidly enough to maintain population levels, given the long interval between birth and sexual maturity. Major declines in shark stocks have been recorded—some species have been depleted by over 90% over the past 20–30 years with a population decline of 70%. Other threats include habitat alteration, damage and loss from coastal development, pollution and the impact of fisheries on the seabed and prey species. Shark finning attracts much controversy and regulations are being enacted to prevent it from occurring. Even though many governments and the UN have acknowledged the need for shark fisheries management, little progress has been actually made due to their low economic value.

Behavior and Reproduction of Sharks

Behavior

The classic view describes a solitary hunter ranging the oceans in search of food. Migration patterns in sharks may be even more complex than in birds, with many sharks covering entire ocean basins. However, shark behavior has only begun to be formally studied, so there is much more to learn. Sharks can be highly social, remaining in large schools, sometimes over 100 scalloped hammerheads congregate around seamounts and islands. When approached too closely some sharks perform a threat display to warn off prospective predators. This usually consists of exaggerated swimming movements, and can vary in intensity according to the threat level.

Reproduction

Sharks practice internal fertilization. The posterior part of a male shark's pelvic fins are modified into a pair of intromittent organs called claspers which are used to deliver sperm into the female. Mating has rarely been observed in sharks. The male may bite the female to show his interest.

Physical Characteristics of Sharks

Skeleton

Shark skeletons are very different from that of bony fish. Sharks and other cartilaginous fish (such as skates and rays) have skeletons made from cartilage and connective tissue. Cartilage is flexible, durable, and has about half the density of bone. This reduces the skeleton’s weight and also saves energy. Sharks have no rib cage and therefore on land a shark's own weight can literally crush it.

Jaw

The shark's jaw is not attached to the cranium. The jaw's surface needs extra support due to its heavier exposure to physical stress and its need for strength. It has a layer of tiny hexagonal plates called "tesserae", which are crystal blocks of calcium salts arranged as a mosaic. This gives these areas much of the same strength found in the real bony tissue found in other animals. Generally there is only one layer of tesserae in sharks, but the jaws of large specimens (such as the bull shark, tiger shark and the great white shark) have two to three layers or more, depending on body size. In the snout, the cartilage can be spongy and flexible to absorb the power of impacts.

Teeth

The teeth of sharks are embedded in the gums rather than directly fixed to the jaw. They are constantly replaced throughout the shark's life. Multiple rows of replacement teeth are grown in a groove on the inside of the jaw and moved forward in a "conveyor belt". Some sharks lose up to 30,000 or more teeth in their lifetime. The rate of tooth replacement varies from once every 8–10 days to several months. In most species, teeth are replaced one at a time. The shape of a shark's tooth depends on its diet. Those that feed on mollusks and crustaceans have dense flattened teeth for crushin, those that feed on fish have needle-like teeth for gripping and those that feed on larger prey such as mammals have pointed lower teeth for gripping and triangular upper teeth with serrated edges for cutting.

Fins

The fin skeletons are elongated and supported with soft and unsegmented rays named ceratotrichia. Sharks can only drift away from objects directly in front of them because their fins do not allow them to swim backwards

Skin

Sharks' dermal teeth give them hydrodynamic advantages as they reduce turbulence when swimming. These work as an outer skeleton, providing attachment for their swimming muscles and also saving energy.

Tails

Sharks have very distinctive tails. The tails of sharks vary considerably between species and are adapted to the lifestyle of the shark. The tail provides thrust and so speed and acceleration are dependent on tail shape. Different tail shapes have evolved in sharks adapted for different environments. They possess a heterocercal caudal fin in which the dorsal portion is usually larger than the ventral portion. This is due to the fact that the shark's vertebral column extends into that dorsal portion. This is in contrast to most bony fishes, which possess a homocercal caudal fin

Introducing Sharks

Sharks are very interesting sea creatures and this is probably the reason behind why i am researching on them. When the word "shark" is mentioned, many people would immediately describe its nature as dangerous. Some may even associate it with shark fin soup. Thus, i feel that the all of us should be more educated about sharks as their populations are actually declining.

What are 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, even before the time of the dinosaurs. Since that time, they have already diversified into 440 species. They are found in all seas and are common down to depths of 2000 metres. They generally do not live in freshwater and respire with the use of five to seven gill slits. Sharks have a covering of dermal denticles that protect their skin from damage and parasites and improve fluid dynamics so the shark can move faster. They also have several sets of replaceable teeth. Well-known species such as the great white and the hammerhead are apex predators at the top of the underwater food chain. Their extraordinary skills as predators fascinate and frighten humans, even as their survival is under serious threat from fishing and other human activities.

To Kill a Mocking Bird

Consider these questions: Is Maycomb a good place to live in? Is Maycomb corrupted? [focus on 2 main themes: Courage and Prejudice]
Since the 2 highest scores in my learning profile are linguistic and interpersonal, I am doing "Imagine you are one of the characters. Deliver a speech on what you think of the above question." and "Conduct an interview with a friend (not from HCI) or family member. Find out from their point of view on prejudice and discrimination. Either record the interview or write out the interview transcript."

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“We are all equal! Maycomb is our homeland. This is where we all belong. Nobody should be discriminated, neither the blacks nor we. What makes them inferior as compared to us? The colours of their skins? No! We are all human beings. They are very much the same with you and me.

Imagine if you are in their shoes, how would you feel? Horrified, disgusted and outraged? What crimes have they committed by just being a black? Why do we hate those innocent people? Our actions now will affect us in the future. They may have once been a slave, but no longer now. We should instantly destroy the mindset of segregation. We should live together in harmony with the blacks.

Despite knowing the fact that he will definitely loose, Tom Robinson has still mustered all his courage to stand before you and I, hoping for a chance. Don't you feel that we should all give him a chance? DO you want others to say that Maycomb is a corrupted place to live in? The future of Maycomb lies in your hands now and i implore you to change your mind. Thanks you. "

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Interviewee: Mother

Prejudice is the preconceived opinion that is not based on reason or actual experience. For example there are some employers nowadays who do not practice fair employment. They do not only look at merits, qualifications and experience but also the looks of people. They just would not employ someone who looks ugly despite having all the requirements for the job.

Discrimination means to make an unjust or prejudicial distinction in the treatment of different categories of people especially on the grounds of race. For example, the whites discriminated the blacks and they were marginalized from the common community. They were not allowed into restaurants containing white people in the past.

Discovering your Learning Profile

After completing the MIDAS test (a short 40 questions test to allow me to find out more about my learning profile), I found out that I excel the most in the fields of linguistic and interpersonal.

Linguistics means to be good at the scientific study of natural language that encompasses a number of sub-fields. To put it in a simpler way, it means that I am good at my languages. However, I feel that this is not exactly correct as I am only among the average in my languages.

Interpersonal usually refers to the relationships or communications between people. To also put it in a simpler way, it means that you are able to communicate well and have a good relationship with others. I feel that this indeed suits me as I rarely get into an argument with people or saying things that offend others.

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Overall, I feel that MIDAS test is rather effective and most of the results match my own personality. However, I would also like to point out that it is not 100% accurate. This is because there are only 40 questions that we have to answer and these are certainly not enough to find out about your true personality. An example would be as earlier mentioned the results show that I am a linguistic person, but this does not really match me. Although I have to agree that it very useful, I feel that it can still be improved by adding more effective questions.