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