| More than a million and a half species of animal have | | | | Nematoda), they have a thin, cylindrical body that is |
| been described, and there millions more so far to be | | | | pointed at the end on both sides. You'll find your |
| described. Animals are living organisms found in literally | | | | nematodes in many habitats and dwell in large |
| all of the Earth's habitats, including the depths of the | | | | numbers in the earth's soil. Nematodes are parasites of |
| oceans, the freezing Arctic, and even within other | | | | some animals and plants. |
| animals and plants. | | | | Sponges, what are they? |
| The animal kingdom is divided up into animals without | | | | The animals perceived the most basic are sponges |
| backbones (invertebrates) which include lobsters and | | | | (phylum Porifera). There are about 5,000 species; most |
| snails, and animals that do have backbones | | | | of them dwell in the sea attached to rocks and other |
| (vertebrates), animals like monkeys and zebras. | | | | things. The water is taken in through holes, or pores, in |
| Invertebrates make 97 per cent of all animal species. | | | | the sponge's body wall, and bits of food are filtered |
| What is an animal? | | | | out and eaten by the sponge's cells. |
| Animals are made up of many cells. The majority of | | | | What are cnidarians? |
| these cells move around, and the ones that have fixed | | | | Today there are a recorded 9 thousand species of |
| positions, or sedentary, move the animal's actual body | | | | cnidarians (phylum Cnidaria), most of them live in the |
| parts. Animals survive by fetching food into their | | | | sea. They include jellyfish, sea anemones, hydras, and |
| bodies. They have their own nervous and sensors | | | | corals. Cnidarians catch food for their bodies using their |
| systems that enable them to observe what is | | | | armed tentacles which have stinging threads, called |
| happening around them and react rightly. | | | | nematocysts. |
| The classification of animals | | | | Animal skeletons |
| Animals are put into groupings based on evidential | | | | The animal skeleton works as a support framework |
| similarities and whether they have ancestral similarities. | | | | that maintains an animal's body shape and allows the |
| There are Thirty-five big groups called phyla (singular | | | | animal to move. The majority of skeletons in animals |
| phylum). Each phylum is shared into small groups. The | | | | are hard structures, either within or outside the animal's |
| least of these is the species, which contains animals | | | | body where the muscles are attached. Animal's body, |
| consisting of only one type. | | | | to which muscles are attached the skeleton usually |
| Flatworms | | | | protects the animals internet organs and, which is |
| These worms (phylum Platyhelminthes) have a body | | | | evident in an insect's external skeleton, which helps the |
| that's flattened with one opening, its mouth, which is on | | | | animal from dying out. The skeleton found within the |
| the underside. There are currently over eighteen | | | | body is called an endoskeleton. The harder outer |
| thousand species including those, such as tapeworms, | | | | skeleton that features over all or some of the body is |
| that are parasites of human beings and other animals | | | | called an exoskeleton. Hydrostatic skeleton is an |
| within the kingdom. | | | | internal skeleton found in soft-bodied animals like |
| Nematodes | | | | earthworms and its kind. |
| They are roundworms, or nematodes (phylum | | | | |