The Kingdom Animalia is a huge group that consists of eukaryotic, multicellular organisms that room heterotrophic in nature. As such, they achieve their nutrition from external sources. Return they are unable to produce their own food, which is among the main defining features of plants, animal cells absence a cell wall that is current in plant cells.

With the exception of a couple of animals, the bulk of pets are motile which allows them to properly respond to stimuli and find food, etc. In general, animals are split into two main groups namely, vertebrates (animals with a backbone) and also invertebrates (animals that absence a backbone). However, castle are also divided into several phyla that will certainly be discussed below in detail. 


Some instances of pets include:


Human beings CowsFishBirdsSponges - InvertebrateLobster - InvertebrateSpiders - InvertebrateClams - Invertebrate


Kingdom Animalia Classification

As mentioned, all animals are split into two key categories/groups: vertebrates and also invertebrates



Vertebrates incorporate all pets classified under the subphylum Vertebrata. Lock belong come the phylum Chordata and possess a backbone/vertebrae (where the spinal cord is located). Castle are also characterized by an internal skeletal system on i beg your pardon muscles are attached.

Vertebrate pets are classified into seven key classes the include:


The majority of species are defined by epidermal hair and the females give birth and also suckle the young. However, duck-billed and spiny anteater place eggs. 

Aves/Birds - animals that are defined by wings, feathers, and also a beak. Reproduction requires laying egg that vary in size depending on the form of bird. Examples of birds encompass kiwi, emu, chicken, and woodpecker amongst others. Part birds have actually wings but cannot fly. Top top the various other hand, some animals like bats have actually wings however are classified together mammals. Therefore, no all animals that fly space classified as birds.

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Reptiles (cold-blooded) space four-legged animals and are identified by the existence of a tail and dermal scales. For the bulk of species, eggs space fertilized internally resulting in direct development of the organism. Reptile examples encompass turtles, snakes, and crocodiles amongst others. 


Examples the Amphibia by Prehistoricplanes / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)

Amphibians encompass cold-blooded pets that spend component of their lives in water. If they have the right to absorb oxygen with their skin in a moist environment, some species (or in some phase of their life) have gills offered to breathe in water. They can additionally breathe utilizing lungs on land. They put jelly-like egg in moist settings or in water and include frogs and salamanders etc.


This group consists of jaw-less animals that look prefer fish. Few of the types like Lampreys are identified by a large head, a notochord, and also a sensory system. 


Example the Osteichthyes by Prehistoricplanes / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)

Osteichthyes are true fish and also are often referred to as bony fish. Together such, lock are characterized by bone tissue (rather 보다 cartilage). Few of the other characteristics connected with this group encompass fused teeth, lobed fins, and a skull. Members that this group include clownfish and ray-finned fish amongst others.

Chondrichthyes by Prehistoricplanes - very own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=84071029

Chondrichthyes is composed of organisms v a cartilaginous skeleton and also are as such known as cartilaginous fishes. When a few species have been established in freshwater environments, the bulk of varieties are discovered throughout the ocean. 

Given the vertebrate animals comprise a single phylum, they comprise less than 5 (5) percent of all recognized animals.


While vertebrates consist of of just one phylum, invertebrates make up the remaining phyla that the kingdom Animalia. As the surname suggests, invertebrates lack a backbone and internal skeletons. Few of the species have an outside skeletal system, the exoskeleton, that provides structural support. Currently, invertebrates are said to comprise over 97 percent of all pets in the pet kingdom. 

Being such a varied group, invertebrates are classified based upon a variety of characteristics including morphology/structure, symmetry and also life cycle, etc.

Whereas some of the organisms have actually three body layers, others (primitive invertebrates) only have two human body layers. Examples of invertebrate pets include insects (like spiders and also ticks), snails, sea stars, sponges, and hydra, etc. 

Jellyfish, Invertebrate image by Pexels indigenous Pixabay

Levels the Organization

While all pets within the kingdom Animalia room multicellular organisms, castle exhibit different patterns of cabinet organization. For this reason, lock are additionally classified based on the level of company of your cells. 

Here, castle are split into three main levels i m sorry include:


Cellular level - The cells of animals at this level of organization type loose aggregates. If the cells of these animals (e.g. Sponges) are devoted in a path that permits them to perform different functions, cells the are comparable are not organized together to form tissue.

For this reason, the body of this organisms are loosened aggregations that consist of different species of cells. While the cell in this organisms room not have to organized right into tissue, it"s worth noting that some of the cell (e.g. Pinacocytes) type layers and also serve provided functions.


Tissue level that organization - animals with this level that organization have actually cells that execute the exact same functions and are arranged together to kind tissue. Because that the majority of this organisms, the body consists of two main layers that are separated by a middle layer known as mesogloea (the middle/third great is non-cellular).

Being diploblastic (consist that two main layers the cells), this organism consists of an outer layer recognized as the ectoderm, consisting of the epidermis, and the inner layer the lines the inner part of the body recognized as the endoderm (making increase the gastrodermis). The body additionally consists of an inner body cavity. 


Organ device level the organization - because that organisms with this level that organization, the tissues room arranged with each other to form organs.

While all the cell in the organ may not perform the very same functions, they room related and contribute come the purpose of the organ. Few of the organisms v this level of organization include less complicated organisms like Platyhelminthes and other biology of the greater phyla (human us etc).

Here, guts are also connected in an organ device and function together. A an excellent example that this is one organ mechanism that consists of the kidneys, bladder, and the ureter developing a practical urinary system. While each of the organs has actually a various function, they room all involved in the removed of waste product from the body. 


In enhancement to the level the organization, pets are additionally classified based on body symmetry (arrangement of the parts of the body roughly the central point). 

While some of the organisms are asymmetrical, and also can thus not be separated into two equal or comparable halves follow me the central plane, others space symmetrical where the 2 halves will certainly be equal/similar once the human body is separated into two parts along the main plane. 

Generally, the bulk of organisms at the moving level the organization have actually been presented to it is in asymmetrical when those at the tissue/organ level of company are one of two people radial or bilaterally symmetrical.

For animals that exhibit bilateral the opposite (e.g. Human beings, butterfly, dogs, etc), splitting the organisms into two halves native the head to the tail follow me the central part will result in two equal halves. Each fifty percent will be a mirror photo of the other. 

An image representing bilateral symmetry. The red line separating the insect right into two halves shows how each half is a mirror photo of the other half. Credit: lifwynnfoundation.org

Several animals have radial symmetry and can, therefore, have many lines that symmetry. Due to the fact that they have actually several components arranged around the main point, they have the right to be split along several lines and be surrounding showing department resulting in halves that are mirror pictures of the various other half.

Some that the organisms through radial symmetry include corals, sea anemones, and also jelly fish amongst others.

Unlike animals with bilateral symmetry, those through radial symmetry have the right to be separated along number of lines. The complying with image demonstrates radial symmetry of a starfish. Credit: lifwynnfoundation.org

Compared to pets that are characterized by bilateral symmetry, a great number the these pets (with radial symmetry) perform not have actually bodies with unique fronts (head parts) and ends. Rather, their bodies are mostly characterized by top and also bottom sides with various essential organs being located on this sides.

The mouth component of a starfish is located at the central part the the reduced or bottom surface. They are commonly found in aquatic atmospheres where they feed on food material ceded by water currents. 

While a good number the animals, particularly those through a tissue or body organ level that organization, are identified by a radial or bilateral symmetry, part animals, particularly those with a to move level of company (e.g. Sponges) often tend to be asymmetrical and also therefore cannot be separated into 2 equal halves. Many of this organisms are an easy with a basic body plan because the cells space not organized into tissue or organs. 


Diagrammatic representation of a sponge – by looking in ~ this image, it"s evident that it can not be divided into 2 equal halves. Together such, it"s asymmetrical.

Diagrammatic depiction of a sponge, Asymmetrical. Credit. lifwynnfoundation.org

Body Cavity/Coelom

Animals are also classified top top the basis of body cavity (coelom). This cavity is normally formed during embryo development. Unlike the gut, which consists of the endoderm, the coelom is surrounding by the mesoderm.

For this reason, the majority of pets with a coelom have a mesoderm. It"s located between the body wall surface of one organism and also the alimentary canal. Some instances of this cavities in the body encompass the peritoneal cavity and the an are around the lungs. 

Some of the main features of this cavity include:


· Protecting offal from mechanical shock

· specifies the shape of part organisms and likewise contributes to locomotion 

· involved in the deliver of gases, nutrients, and also waste material

· provides a room required for breakthrough and attributes of offered organs


Based top top the body cavity, animals are classified right into the adhering to groups:


As the name suggests, acoelomates are pets that lack a true body cavity. The bulk of these animals are straightforward organisms consisting of members that the phylum Platyhelminthes.

Because they absence a true body cavity, the mesodermal tissue plays critical role in holding provided tissue or offal in place. Acoelomates incorporate a range of pets including several of those v radial and also bilateral symmetry and asymmetric animals. 

See likewise Helminths.

Pseudocoelomates (animals that have a false coelom)

While organisms classified in this team have a human body cavity, the cavity is not obtained from the mesoderm. Because that this reason, the cavity is often referred to together a false coelom. Several of the many pseudocoelomates include rotifers and also nematodes. The human body cavity of these organisms is known as pseudocoel (and thus the surname pseudocoelomates) and also includes pets with bilateral symmetry. 

In enhancement to a few mesenchyme tissue, this cavity may consist of liquid or a gelatinous substance. Some of the main functions of pseudocoel incorporate those associated with digestion, reproduction, and also distribution of nutrients in the body. Some of the various other organisms classified together Pseudocoelomates encompass members of the teams Loricifera, Gastrotricha, and Entoprocta. 

See also Nematology.


Coelomates include animals with a true coelom. The majority of these organisms are characterized by a tissue or organ device of organization and also have bilateral symmetry. Unequal Pseudocoelomates, coelomates have actually a coelom that is completely or fully derived from the mesoderm.

As a room that is located between the body wall surface and the gut in all vertebrates, it"s enclosed in between two varieties of cells (cells that underlie the body wall surface and those the surround the gut).

Coelomate invertebrates, top top the various other hand, space triploblastic and also are characterized by 3 cellular human body layers that include the ectoderm, mesoderm, and also endoderm.

Although it"s located in between the body wall surface and the gut, it"s precious noting that this cavity is not in direct contact with either. Rather, it"s separated native the two by the peritoneum (peritoneal epithelium).

The following is a diagram design of a mollusk (phylum Mollusca) showing ar of the coelom:


* As the coelom rises in size, contact in between the body wall and the peritoneum increases.

Diagram model of a mollusk showing location of the coelom. Credit: lifwynnfoundation.org

Different Phylum under the Kingdom Animalia

In biology, a Phylum is a taxonomic category/level the ranks below Kingdom but above Class. It"s an important category that groups organisms based on a set of characteristics that set them personal from various other organisms. 

In the Kingdom Animalia, animals are separated into a full of eleven (11) Phyla that include:


Kingdom Animalia: Phylum Chordata

The surname Chordata comes from the Greek words "Chorde" an interpretation cord or string and "ata" which means bearing. Therefore, chordates (members of the Phylum Chordata) are animals that have actually a notochord/cord at some point of your lives.

While the majority of animals in the Phylum Chordata have actually a vertebrate (the majority of greater animals), the group additionally consists of protochordates (e.g. Squirts and also amphioxus) which are closely related come vertebrates. If they lack a backbone i beg your pardon is current in all vertebrates, these organisms have a dorsal nerve cord and also a notochord and thus qualify to it is in classified under the Phylum Chordata. 

Currently, there are an approximated 65,000 chordate species. When there space not countless when contrasted to some of the various other groups, they exhibit good diversity and also can be found in a range of habitats, in aquatic and also terrestrial environments, across the world. 

Some instances of chordates include:




Main attributes of Chordates


· majority of these organisms have an anterior finish that might consist that a head or cephalic region and a posterior finish that covers a tail in a bulk of animals

· Bilateral symmetry

· majority of animals are triploblastic and thus have actually the three germinal layers (ectoderm, endoderm, and mesoderm)

· have a coelom

· identified by an organ-system level of organization 

Kingdom Animalia: Phylum Porifera


The Phylum Porifera consists of few of the earliest well-known animals. Lock are frequently found in aquatic settings (particularly in maritime environments) wherein they feeding by filtering water in order come trap and capture essential material. Organisms like Sponges space filter feeders and have been presented to be qualified of catching about 70 percent of exposed bacteria and also organic matter in your surroundings. 

For the many part, members the this Phylum are basal pets characterized through a cellular level the organization. As such, they lack true tissue given that cells are not organized into tissue systems.

Because they lack true tissues, and also thus body organ systems, members that the Phylum are generally identified by an aquiferous device that is composed of canal networks and also chambers that permit water to flow in and out. 

Some organisms that belong come the Phylum Porifera include:


DemospongeCalcareous spongeSiliceous spongeHexactinellid sponge


Kingdom Animalia: Phylum Platyhelminthes


The Phylum Platyhelminthes include organisms known as flatworms. They room dorsoventrally planarization worms and thus lack a coelom. The space between human body organs is therefore filled through mesenchyme. Back they have a tissue/organ system level of organization (e.g. Have a reproductive system), they lack a circulatory system, a respiratory system, and also a true anus.

Like few of the various other animals, these organisms room triploblastic and therefore have actually three embryonic cabinet layers (the ectoderm, endoderm, and mesoderm). Lock are also bilaterally symmetrical and also can, therefore, be separated into two equal halves native head come tail.

While some of the organisms (e.g. Members the the course Turbellaria) can survive in too much environmental conditions (in sand and rocks etc), the bulk of flatworms deserve to be uncovered in aquatic and also moist environments. 

Some that the organisms the belong come the Phylum Platyhelminthes include: 


·  Turbellaria (e.g. Gyratrix hermaphroditus, Pseudoceros dimidiatus, Girardia tigrina) 

· Trematoda (e.g. Clonorchis sinensis, Schistosoma japonicum, and also Metagonimus yokogawai etc) 

· Cestoda (e.g. Pork tapeworm, fish tapeworm, and Taenia taeniaeformis etc). 


Kingdom Animalia: Phylum Cnidaria


Also well-known as Coelenterata, the Phylum Cnidaria is composed of organisms that are frequently found in naval environments. However, a couple of species, choose Hydra, deserve to be discovered in freshwater environments.

While there are many types of the Phylum Cnidaria, they all have actually a basic body structure that consists of 2 cellular class (endoderm and the ectoderm). These layers space separated by the mesoglea i m sorry is a non-cellular, gelatinous layer.

Although castle are straightforward organisms, they have actually true tissues consisting of the epithelial tissue, muscular tissue, and also connective tissue, etc. However, they carry out not have an body organ level the organization and are because of this classified in the tissue grade. Due to the fact that of their basic morphology, they have actually radial symmetry and also can, therefore, be divided along number of planes. 

Some of the varieties that belong to the Phylum Cnidaria include:


HydroidsCoralsJelly-fishesSea anemonesPolyps

Kingdom Animalia: Phylum Annelida

Members that the Phylum Annelida, recognized as annelids, are segmented worms found in miscellaneous habitats, in aquatic and also terrestrial environments. While lock exhibit far-reaching diversity with regards come the body plan, studies have revealed the the majority of varieties are coelomate and thus have a human body cavity. 

They are likewise characterized by multiple body segments with the first segment (prostomium) consisting of the brain in many of the organisms. The human body of these organisms can be split into three key regions including the prostomium (the head part of the body), the tribe which consists of lot of segments, and also the pygidium i beg your pardon is the post-segmental region. They additionally contain several inner organs that comprise the digestive system and circulatory system etc. 


* Annelids likewise display bilateral symmetry. 


Some that the species that belong to the Phylum Annelida include:


EarthwormSludge wormMedicinal leechLugwormSalinera


Kingdom Animalia: Phylum Mollusca

Members that the Phylum Mollusca (mollusks) room coelomate organisms that exhibit bilateral symmetry. However, few of the varieties exhibit asymmetrical conditions later on in life. Lock usually have a soft human body that might be safeguarded by a calcareous shell relying on the organism. The ventral component of the body of mollusks consists of a muscular device used because that locomotion. 

Generally, the majority of these organisms space aquatic and can, therefore, be found in marine and freshwater settings (a few species are discovered in freshwater). However, some of the types can likewise be discovered in terrestrial environments. 

Some of the various other characteristics linked with mollusks include:


· room triploblastic and also therefore have actually three main layers

· have actually an organ system level the organization 

· body cavity (the true coelom) is restricted to the pericardial cavity and lumen the the gonads

· have an open up circulatory system 

· Organs the are unique to mollusks encompass the radula (a feeding structure) and also the mantle (a dorsal layer)



Some of the varieties that belong to the Phylum Mollusca include:


Giant clam Pacific oystersHard clam Garden snail Freshwater pearl mussel 


Kingdom Animalia: Phylum Arthropoda

Members of the Phylum Arthropoda are recognized as arthropods. Although they room invertebrates, arthropods have an exoskeleton that gives structural assistance to the organism. Generally, arthropods are defined by a segmented body (consisting the a head, thorax, and also abdomen) as well as jointed appendages. 

Currently, it"s estimated that there space over one (1) million varieties of the Phylum Arthropoda make it among the largest groups of the pet kingdom. End 80 percent that all pets on planet are arthropods. Every arthropods have a true coelom the is little in size. 

They also exhibit an organ system level of organization with organs developing various body organ systems consisting of the digestive system, circulatory system, and the concerned system, etc. They also exhibit bilateral symmetry wherein the body deserve to be split into 2 equal halves. 

Some of the organisms the belong come the Phylum Arthropoda include:




Kingdom Animalia: Phylum Hemichordata

Members the the Phylum Hemichordata (Hemichordates) space worm-like invertebrates frequently found in marine environments. Your bodies are divided into three main parts including the proboscis, the collar (mesosome), and also the trunk (posterior part of the body). 

They exhibition bilateral symmetry and also thus the body can be split into two equal halves. Since they re-superstructure several qualities with chordates and members the the Phylum Echinodermata, Hemichordates room sometimes taken into consideration to it is in the link in between vertebrate and invertebrate animals.

Like several of the other organisms, members of this team (especially adult organisms) have coeloms, however lack properly arisen organ systems as those found in most higher animals. 

Some that the pets classified under the Phylum Hemichordata include:


Planctosphaera pelagicaPtychodera flavaSpartobranchus tenuisGlossobalanus minutus


Kingdom Animalia: Phylum Echinodermata


The surname Echinodermata is obtained from the Greek words "echinos" which method spiny and also "Dermos" which means skin. Therefore, together the name suggests, this organisms are defined by a spiny skin. 

Members the this team (echinoderms) are commonly found in marine habitats where they feeding on seaweed. They are additionally described together invertebrate coelomates offered that they have actually a spacious coelom located in between the gut and also body wall. 

They exhibit an organ system level of organization and also posses various important structures consisting of a mouth and a finish digestive system. Back they deserve to reproduce sexually, they are additionally capable the regeneration. 

Some the the types classified under this phylum include:


Common starfish Green sea urchinEchinus esculentus Blue sea star ArkaruaProtoreaster nodosus 


Members that this group generally exhibit radial symmetry


Kingdom Animalia: Phylum Ctenophora

Members that the Phylum Ctenophora are generally referred to as Ctenophores. They space invertebrate organisms commonly found in maritime waters across the globe. Ctenophores room jelly-like organisms characterized by a soft-body that exhibits biradial symmetry.

Like Platyhelminthes and also members of the Phylum Cnidaria, Ctenophores space acoelomate and also thus lack a true body cavity. Members of this group are also characterized by comb rows (eight in total) used for movement. 

Some of the organisms the belong to this phylum include:


Beroe ovataPleurobrachia bacheiBeroe cucumisXanioascusCtenorhabdotus capulus


Kingdom Animalia: Phylum Aschelminthes

Aschelminthes are aquatic biology that are bilaterally symmetrical and exhibit one organ-system level that organization. They are triploblastic and also therefore have actually three germinal layers (ectoderm, endoderm, and also mesoderm).

Although they have a flattened, worm-like body, studies have displayed them to it is in pseudocoelomate (which originates from the blastocoel) and also therefore do not have actually a true body cavity. They lack the respiratory and also circulatory system frequently found in other animals but have a cradle tract.

Some that the species that belong come this Phylum include:


Horsehair wormsTrichinella spiralisLoriciferaLoa loa

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Agu K C. (2012). Vertebrates.

Joshua Bishop Roby. (2009). Pet Kingdom. 

Kevin Pang and Mark Q. Martindale. Ctenophores. 

P.S. Verma and also S. Chand. (2013). Chordate Zoology.

See more: Cubic Feet To Gallons Convert Square Feet To Gallons Of Water Per Square Feet

Richard E. Blackwelder. (1963). Group of the animal KINGDOM 

Teresa Adell et al. (2015). Platyhelminthes. 

Thomas Jankowski and also Boris Anokhin. (2019). Phylum Cnidaria.