Today is

By: Ikedi Ani-okoye.

Animal

More than a million and a half species of animal have been identified, and there millions more yet to be discovered. Animals are living organisms found in nearly all of the Earth's habitats, including the depths of the oceans, the freezing Arctic, and even Inside other animals and plants.

The animal kingdom is divided into animals without backbones (invertebrates) such as snails and lobsters, and animals with backbones (vertebrates), such as frogs and monkeys. Invertebrates make 97 per cent of all animal species.

What is an animal?

Animals are made up of many cells. Most move actively, and those that are fixed in one place, or sedentary, move their body parts. Animals live by taking food into their bodies. They have sensors and nervous systems that enable them to detect what is happening around them and respond appropriately.

Animal classification

Animals are classified into groups according to their similarities and whether they have common ancestors. There are 35 major groups called phyla (singular phylum). Each phylum is divided into sub-groups. The smallest of these is the species, which contains animals of just one type.

Flatworms

These worms (phylum Platyhelminthes) have a flattened body with one opening, the mouth, on the underside. These are about 18,500 species including those, such as tapeworms, that are parasites of humans and other animals.

Nematodes

Roundworms, or nematodes (phylum Nematoda), have a thin, cylindrical body that is pointed at both ends. Free-living nematodes are found in many habitats and occur in very larger numbers in soil. Many nematodes are parasites of plants and animals.

Sponges

The simplest animals are sponges (phylum Porifera). There are about 5,000 species, most of which live in the sea attached to rocks and other objects. Water is drawn in through holes, or pores, in the sponge's body wall, and bits of food are filtered out and eaten by the sponge's cells.

Cnidarians

There are more than 9,000 species of cnidarians (phylum Cnidaria), most of which are found in the sea. They include jellyfish, sea anemones, hydras, and corals. Cnidarians catch food using tentacles armed "dth stinging threads, called nematocysts.

Animal skeletons

The skeleton is a supportive framework that maintains the shape of an animal and enables it to move. Most skeletons are hard structures, either inside or outside the animal's body to which muscles are attached. animal's body, to which muscles are attached The skeleton may also protect internal organs and, in the case of an insect's external skeleton, prevent the animal from drying out. A skeleton Found inside the body is called an endoskeleton. hard outer skeleton that covers all or part of the body is called an exoskeleton. hydrostatic skeleton is an internal skeleton found in soft-bodied animals such as earthworms.