‘Amazing Habitats: Oceans’
‘Amazing Habitats: Oceans’ by Leon Gray
1. An orca leaps from the water. This behaviour is called breaching.
2. There are three ocean zones between the surface of the water and the sea floor. The top zone is called the sunlit zone because it is bathed in sunlight during the day. Most ocean animals and plants live in the sunlit zone. As you sink deeper into the twilight zone, the light fades, the water gets cooler and the water pressure increases. The dark zone is at the bottom of the ocean depths. This is a world of total darkness. Few animals and no plants can survive. The hatchetfish lives in the dark zone.
3. Most of the ocean’s plant life consist of algae. Most algae that live in the ocean are tiny. They can only be seen under a microscope. Algae are not true plants. They do not have roots, stems and leaves. Like true plants, algae need sunlight to grow. They can grow on the ocean shore and in the top 200 metres of the ocean. Light does not reach any deeper than that, so algae cannot grow there.
4. Kelp is a kind of seaweed. It grows from the sea floor up to 45 metres to the surface. In some places, there is so much kelp that it forms an underground forest.
5. Millions of tiny organisms drift around in the sunlit zone at the top of the ocean. They are called plankton. Some are plant-like algae, others are microscopic animals. Plankton is very important. Many sea creatures, from fish to whales, depend on plankton for their food.
6. Sea grasses are the only flowering plants that live under the ocean. They grow best in clear, shallow waters. Sea grasses produce flowers, fruits and seeds just like plants on land. They form large meadows on the ocean floor.
7. The roots of mangrove trees filter out salt from the seawater. Mangrove trees store the salt in their leaves. After a while, the trees get rid of the excess salt by shedding some of their leaves.
8. Sea turtles live in the warm waters of the Atlantic, Pacific and Indian oceans. Male green sea turtles never leave the water. Females come ashore every two years to lay their eggs. These turtles can hold their breath for hours as they swim underwater looking for food. Young turtles eat crabs and jellyfish but adults are vegetarians.
9. Dugongs are herbivores that graze on sea grasses and algae on the ocean floor. They live in tropical parts of the Indian and Pacific oceans. They can hold their breath for up to 6 minutes while they feed.
10. Fangfish live in the murky ocean depths, 2800 metres beneath the surface. These fish can make their own light, called bioluminescence. The fangfish switch off this body light when they are hunting so that their prey cannot see them.
