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Corals are carnivores that with their vivid colours and ofte flashy body really look like plants. Corals can reproduce asexually by budding and can be propagated sexually. The builders of coral reefs are tiny animals called polyps. The polyps feed with tentacles, which they extend at night to catch tiny floating animals, or zooplankton. As these polyps grow, then die, they leave their skeletons behind which are colonized by new polyps. Therefore, a coral reef is built up of layers of these skeletons covered ultimately by living polyps. Coral reefs are the most beautiful ornaments of our planet created mostly in the tropic waters of the Pacific Ocean. There are 3 types of coral reefs: fringing coral reefs (created in shallow water), barrier reefs (separated from land by a lagoon and atolls (ring-shaped and located near the water surface).

koralji	spužva

Sponges are animals that don't move, they are attached to the base. There are about 5,000 species of sponges found throughout the world. Most sponges are found in oceans, although some groups are found in fresh waters such as lakes. They were the first group of animals that has specialized cells to do special jobs. However, the cells are not so advanced as to form tissues. Sponges live singly or in colonies.

Many sponges give off a toxic or poisonous substance. This is used to fight off enemies and poison them. However, some of the substances given off are used by humans as medicines. The skeleton of the sponge is used by man for sponges as well.

Some sponges appear green because algae clings to them. The algae provide oxygen for the sponge and the sponge provides carbon dioxide for the algae. When two living things live off of one another, it is called symbiosis.

Izvori:  Internet

            Knjiga  „Životinjsko carstvo“

Tekst pripremile: Paulina Horvat, Katarina Mrazović

Ana Poljak Klarić, prof. engleskog jezika