Sharks have lived on Earth for approximately how long?

Sharks have existed for more than 450 million years, whereas the earliest tree, lived around 350 million years ago. Not only are sharks older than trees, but they are also one of the only animals to have survived four of the five mass extinctions – now that’s impressive.

Emma Bernard, a curator of fossil fish at the Museum, says, 'Shark-like scales from the Late Ordovician have been found, but no teeth. If these were from sharks it would suggest that the earliest forms could have been toothless. Scientists are still debating if these were true sharks or shark-like animals.'

Analysis of living sharks, rays and chimaeras suggests that by around 420 million years ago, the chimaeras had already split from the rest of the group. As there are no fossils of these animals from this period of time, this is based solely on the DNA and molecular evidence of modern sharks and chimaeras. It was also around this time that the first plants invaded the land.

By the middle of the Devonian (380 million years ago), the genus Antarctilamna had appeared, looking more like eels than sharks. It is about this time that Cladoselache also evolved. This is the first group that we would recognise as sharks today, but it may well have been part of the chimaera branch, and so technically not a shark. As active predators they had torpedo-shaped bodies, forked tails and dorsal fins.   

Credit : Natural History Museum

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What are the types of seafoods?

Suppose you were offered seaweed, snails, or frozen fish eyes. Would you turn up your nose in disgust? Or would you say, “Yes, please!”?

Food usually comes from plants or animals in this world. Some types of plants and animals do well in cold cities. Other types thrive only in rain forests. What people eat often depends on the plants and animals that are near them.

In Japan, seaweed is an important vegetable. It is part of many meals. In Wales, seaweed is cooked with oatmeal and eaten with bacon. Maybe you eat seaweed. Some jelly-like stuff that comes from seaweed is used in many ice creams and jellies.

Snails baked in garlic and butter is a famous meal from France. It’s called escargot. Sea urchins – raw – are also popular there. Many Inuit like to eat frozen fish eyes.

Do you want ants? Honeypot ants drink a sugary liquid from plants called honeydew. They drink so much of it that they look like little walking honeypots. In Australia and Mexico, people pop the sweet insects into their mouths or spread them on toast.

Australian Aborigines like witchetty grubs, the larvae of beetles and moths.

Bird’s-nest soup is a special Chinese dish. It is made from the nests together, the birds use their saliva. This makes the soup chewy!

In West Africa, where people eat few cooked desserts, a favourite treat is sugar cane! Children simply chew a piece of the plant, which grows in West African forests.

Certain foods may seem strange to you simply because you have not learned to eat them. But people around the world eat – and like – many different kinds of food.


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What food comes from the sea?

Good news for good eaters! The ocean covers more than 70 percent of our planet, and it is filled with plant and animal life. It has something for everyone to enjoy fish of all kinds – sardines, mackerel, salmon, and herring – and other seafood, such as oysters, clam, crabs, lobsters, shrimps, and octopus. What about a shark steak?

How do you like your seafood? In Sweden, you can try pickled herring, smoked salmon, or baked halibut. In Japan, look for thin, cold slices of something pink on your plate. It’s tasty sashimi – raw fish. You also can fill your plate with vitamin-rich sea vegetables. Seaweed is a popular dish in Japan.

For thousands of years, people everywhere have set out to sea in small boats to catch their supper. Today, huge modern fishing fleets have electronic equipment for finding fish.

People catch lobsters in cage-like traps. Shrimps, crabs, and some fish are caught in nets. Oysters are scooped up by machines called dredgers.


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What is the history of sushi?

Where it all began

The story of sushi began in southeast Asia as a fish preservation method. Sushi is the Japanese word for “sour rice”. Some of the earliest documentations of sushi comes from 3rd Century China. Fish caught from the river was then preserved in layers of salt and cooked rice and stored in barrels for about a year. This method helped prevent the fish from spoiling and also gave it a pungent odour and savoury flavour. Chinese people ate just the fish and threw away the rice.

During the 8th Century, this preservation method spread to Japan, where the rice used in the fermentation process began to be eaten with the fish. In the Edo period (between 1603 and 1868), as rice vinegar was invented, people began picking the rice with the vinegar to shorten the fermentation period. This also made the rice much more palatable. Sheet seaweed was also invented around this time and eventually allowed contemporary sushi roll to take form. Sushi then began to be consumed as fast food in Japan. Stalls were set up and people grabbed a few sushi rolls going to work.

As refrigeration became popular, raw fish began to be used instead of fermented ones, making the process much quicker.

In the late 19th Century, when the Japanese began migrating to the U.S., they introduced sushi to the western, world. And by the late 20th Century, this Japanese fast food became popular across the world.

Chemistry behind the taste

In the earliest-known sushi preparations, fermentation occurred as the good bacteria in the rice converted sugar in rice into lactic acid. This lactic acid prevents harmful bacteria such as botulinum to grow and ensures the fish doesn’t spoil. Today, a professional sushi chef trains for years to perfect the art. Every component is given equal importance and the chemical components are studies in detail by sushi chefs. For instance, it takes over two years to master the art of cooking sushi rice. The rice is expected to be in a consistency where it just sticks together without being over-mashed. Each grain of sushi rice consists of a starch known as amylopectin. Therefore while cooking, chefs tend to break open most individual grains using a spatula, releasing the starch and allowing the rice to stick together.


There are many types of traditional sushis and the most famous ones include nigirizushi, makizushi, sashimi, tempura and temaki.

After sushi was introduced in the U.S., it took on many diverse forms to appeal more to the western palate. For instance, the Philadelphia roll is makizushi made with smoked salmon, cream cheese and cucumber; and California roll consists of avocados and faux crab meat.

There are many other quirky varieties such as sushi burritos, deep-fried sushis, sushi burgers, ice-cream sushi and Canadian sushi pizza.


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