Animal Kingdom Classification

Animal kingdom classification is not a job for the faint hearted, for it is a really long list of classes and sub classes, all of which are named in Latin. Makes me wonder why all the great scientists, biologists and physicians only catered to the Latin masses. Oh well, doesn't matter, what's done is done. This classification of the animal kingdom is segregated into phyllum or classes which are in turn bifurcated into sub classes or sub phyllum. Let us begin our animal classification journey, that attempts to classify all animals ranging from single celled microorganisms to highly complex multi-celled organisms. It will definitely not be easy to capture 3.5 billion years of evolution in one small article, but let's give it a shot. My attempt at an animal kingdom classification should help you with the basics, that you wish your child to know. Try not to baffle her with too much Latin, just get her to recognize all the animals and that's enough to make you proud.

Please note that this 'classification of animals' article will only explain the main phylla and not the class, order, family, genus and species. We will leave those for another article. The phylla are the segregation of all animals into smaller recognizable groups based on some unique characteristics that are found in them. Once you are familiar with the phyllum you should automatically be able to gauge which animals fall into which one.

Phyllum Protozoa - Primitive Animals


This phyllum consists of unicellular, usually microscopic, water creatures like amoebae. The common points between all creatures listed under this phyllum are:

• All protozoans move with the help of false feet, known as pseudopodia.
• Small hairlike structures called cilia help in free water locomotion.
• Most protozoans have tails, which are again used for movement.

Protozoans reproduce by the mechanism of binary fission, also known as mitosis. Know more on the classification of amoeba.

Phyllum Porifera - Sponges


This phyllum consists of simple muticellular animals that are mostly found in aquatic habitats. Their unique characteristic is that their cells are held together so loosely that they do not form tissues. Most porifera have pores known as ostia found all over the body and have a large opening on the tops, called an osculum. They have a canal that supports the intake of food and oxygen, and have a support system made up of tiny needle like formations of silica, spongin fibres and calcium. Amazingly, the reproduction in this segment of the animal kingdom may be sexual, asexual or even budding. Some examples of porifera are sycon, spongilla and euptectella. Know more on the different types of sponges.

Phyllum Coelenterata - Cridaria


Mostly found in marine habitats, the animals in this phyllum have a two layered body that is symmetrical. The outer body layer has stinging tentacles that can release venom into the victim's body. The inner body consists of a gastro vasular cavity. This group usually consists of two types of animals (zooids), namely the polyps (fixed, solitary or colonial life) and medusae (free swimming). Reproduction is by budding (asexual) in the polyps and is sexual with the medusae. All types of sea anemones are part of this animal kingdom classification. This group also includes corals, that have an exoskeleton of lime. Know more on facts about sea anemones and also about coral reefs.

Phyllum Platyhelminthes - Aschelminthes


This is a phyllum that includes all the animals once included in the Aschelminthes phyllum, that has now been declared obsolete. Therefore, this phyllum includes all animals like the flatworms and the thread worms. The animals in this phyllum can be segregated into three groups:

• The free living class named Turbellaria.
• The parasitic flukes that fall in the class Trematoda.
• The parasitic tapeworms that consist of the class Cestoda.

The animals in this phyllum are triploblastic organisms, that are mostly parasitic in nature and show bilateral symmetry. Most animals in this phyllum have only one body cavity, that serves as both the mouth and the anus. Both males and the females have both male and female organs on them. Planaria, liver fluke and tape worms also come under this segmentation of animals. Know more on what are the different types of flatworms and human tapeworm.

Phyllum Nematoda – Ascarids


There are numerous species that fall under this phyllum and they consist of most roundworms and eelworms. Know more on roundworm infections. The thousands of eggs that they lay, form cysts and await ingestion. Some of the most important species that fall under this phyllum are:

• Lungworms that cause Hoose.
• Hairworms that are usually the worms that affect school children.
• Potato eelworms and other stomach worms.

Phyllum Annelida – Segmented Worms


This group consists of all the segmented worms, like earthworms, and leeches. Most segmented worms have bristles known as Chaetae, on each segment, that help them move. Segmented worms are mostly found in moist soil, though they can also inhabit fresh water and the sea. These worms have soft bodies that are triploblastic and follow a bilateral symmetry. While reproduction is usually sexual, they have another unique way of reproduction – asexual reproduction through rejuvenation. By regrowing broken segments, these worms can effectively reproduce. Other examples of annelid worms are sand worms and aphrodites (sea mouse). Know more on earthworm classification.

Phyllum Arthropoda – Jointed Legs


With nearly a million species (almost 80% of the animal kingdom) that are a part of this phyllum, this can be said to be the largest one. All arthropods have jointed legs and a visible exoskeletons that shed periodically. Examples of arthropods are scorpions, spiders, shellfish and crustaceans, insects, woodlice, centipedes and millipedes. Arthropods have a bilaterally symmetrical body shape, that is segmented into parts like the head, thorax and abdomen. All arthropods possess jointed legs that enable easy walking, swimming, feeding and feeling. They have a small blood filled body cavity and respiration takes place with the help of lungs, book lungs and tracheae. Even prawn and bees fall under this phyllum.

Phyllum Mollusca – Molluscs and Snails


Molluscs include slugs, snails, squids, mussels, clams and even octopuses. These generally have one foot (I said generally so you can excuse the squids and the octopuses) that excretes a slimy mucus. They possess a rasping tongue that can rip off materials much stronger than them. Though they are mostly found in aquatic habitats, they can also be found on land. Those living in water breathe through gills, while those living on land have fully developed lungs. Mollusks have distinct sexes.

Phyllum Echinodermata – Star Fish


The echinodermata phyllum consists of animals like the asterias (star fish), echinus (sea urchin), holothuria (sea cucumber) and antedon (feather star). Most of these animals are sea creatures with a symmetrical body that is either star shaped, spherical or elongated. Most of them have a spiny exoskeleton and most have no proper head. Locomotion is achieved with the help of tubed feet and both the sexes are separate. Know more information on sea urchins.

Phyllum Chordata – The Most Known Phyllum

This phyllum basically belongs to the animals that can be called vertebrates or those that are closely related to vertebrates, namely the hemichordates. Chordates are divided in many sub phyllums, namely amphibians, reptiles, mammals, marsupials, birds, fish, etc. Let us look at a few of these to understand more on chordates.

Mammals


These have hair or fur, are capable of regulating body temperature, give birth to fully formed babies and produce milk to feed their young. Examples of mammals are monkeys, whales, marsupials like koalas and even man. Know more facts about mammals and facts about koalas.

Amphibians


Amphibians lay eggs, usually in water and breathe through a combination of lungs, gills and skin. They cannot regulate their body temperatures and can live both, on land and in water. Examples of amphibians are frogs, some snakes, etc. Know some more amphibian facts.

Reptiles


Reptiles have roamed the earth since the age of the dinosaurs and adapt well to changes in the environment. Examples of reptiles are alligators, crocodiles, lizards, snakes, tortoises, etc. Though these are air-breathing animals, they can also live in water, but for very short durations (they need to come up above the water level in order to breathe). Reptiles cannot regulate body temperature and they lay eggs. Know more facts about reptiles and the different types of lizards.

Birds


There are over 8000 different species of birds and some examples of them include parrots, sparrows and sea gulls. The characteristics that are only unique to birds are that they have feathered wings, which enable them to fly, have beaks rather than teeth and light bones that make them light enough to fly. They can breathe even at high altitudes and lay eggs to give birth to their young. Know more on the different types of birds.

Fish


Water is home to more than 20,000 different fish varieties, some that are not even known yet. They have gills and they lay eggs. Some fish examples are sharks, goldfish and herring. Know more on the different types of fish. Before I sign off, I urge you to also read on the classification of living things.

There are many many more divisions and subdivisions, but I will stop my animal kingdom classification article here. Hope the article has helped you with learning all the animal kingdom classifications that you were yet unaware of.