Shark vs Dolphin

Can you tell the difference between a shark and a dolphin? Consider the following tips when identifying these two creatures that live in the same ecosystem.

The shark is a cartilaginous fish from a diverse group of animal with about 440 species. It can live in deep and shallow waters. It can be as small as 15 cm long such as the deep sea shark or as long as 12 m like the whale shark. The shark is the top hunter in the marine ecosystem. The shape of its tail varies within species. This creature does not have a swim bladder but its large oil-filled liver and its light cartilaginous skeleton help to keep it afloat. It breathes through gills and it can live for 20- 30 years.

The dolphin has mammalian features. There are about 40 species of dolphins all over the world. The dolphin is mostly found in shallow waters. Its size can vary from one to ten metres in length and from 40 kg to 10 tonnes in weight. Its streamlined body makes it a fast swimmer. It breathes through its lungs. It feeds on fish and squids. Dolphins are intelligent and they hunt in herds. The lifespan of a dolphin is about 20 years.



Test Your Science

1. Give two differences between the shark and the dolphin.

Look up the similarity between the dolphin and the shark in the Young Scientists Issue 109 Level 1.

Protect the Environment

Soil Contamination

Do you know how we can clean contaminated soil? There are three approaches to cleaning it up.

1. We can dig up the soil from the ground and treat or dispose it.
2. We can leave the soil in the ground and treat it in place.
3. We can leave the soil in the ground and control it to prevent the contamination from spreading to plants, animals or humans. This is done by placing a large plastic cover over the contaminated soil to prevent direct contact and keep rainwater from seeping into the soil and spreading the contamination.

Ways of treating soil include the following :~

1. Contaminants are flushed out of the soil using water, chemical solvents or air.
2. Contaminants are destroyed in an incinerator.
3. Natural organisms in the soil are encouraged to break down the contaminants.
4. Material is added to the soil to control the contaminants and prevent them from spreading.



Soil flushing













Adding materials










Incineration









Test Your Science

1. How do you think contaminants in the soil are destroyed in the incinerator?

Find out more about caring and protecting our environment in the Young Scientists Issue 109 Level 2.

Robotic Coffee Table

Let's take a look at the robotic coffee table. By placing some crumbs on the top of the table, mice are attracted to climb up the hole in its over-sized leg. The trapdoor in the centre of the table opens when sensors detect that a mouse is standing on it. The unfortunate rodent then falls into a microbial fuel cell underneath, where it gets digested and converted into energy to power the electronic parts of the table.

Since there might be hundreds of rats hiding behind the walls, we really shouldn't feel sorry for the rats rotting inside the table.

Test Your Science

1. Where does the robotic coffee table get its source of power?

Read the Young Scientists Issue 109 Level 3 on the Carnivorous Robotic Lamp.