Key Difference: Animal kingdom consists of many
different types of animals, but still all the animal share common
characteristics. They all are multicellular means made up of more than
one cell. They do not contain any cell walls like plant cells, and they
usually consume or eat other organisms too.
Kingdom of animals is very diverse and therefore, it becomes little
difficult to place them in different categories. However, the
classification is achieved by using scientific taxonomy. Animals are
placed in different phyla (divisions) based on their characteristics.
Animals are generally classified according to these Phyla –
Anthropod Phylum – It consists of all the jointed
legged invertebrate animals. These animals also bear an exoskeleton,
which refers to the skeleton present on the outside of the body. Nearly
85 percent of the well-known animals belong to this group. These phylum
consists of classes :
Arachnid Class:
it consists of animals like spiders, mites, ticks, scorpions, etc.
They are generally terrestrial and predacious. They usually have sucking
mouthparts. It includes nearly 93,000 species of animals. They possess
four pairs of walking legs. They do not have any wings or antennae, and
this is what makes it apart from insects
Malacostracan Class:
Lobsters, crabs and shrimp fall in this group. It consists of diverse
types of marine, freshwater and terrestrial crustaceans. These animals
are recognized by a maximum of 19 pairs of appendages.Stomatopods,
euphausiids, etc. all belong to this class. Body of Malacostracans is
divided into three tagmata – cephalon, thorax and abdomen. Head and
thorax are combined and therefore it is difficult to differentiate them.
It consists of nearly 25,000 species.
Chilopodan Class:
This class mainly comprises of centipedes. They possess one pair of
antennae and well developed mouthparts. Their body is segmented and each
of these segments contains one pair of legs. The legs in the first body
segment are converted into poisonous jaws. They are insectivorous and
eat other arthropods also.
Diplopodan Class: This
class mainly consists of millipedes. Like centipedes, these are also
many legged arthropods. They primarily feed on decomposed plant
material. The body is divided into two tagmata. They are generally many
centimeters long. They are commonly found under stones and debris, and
also in leaf litter.
Insecta Class: This
class consists of many different types of animal. It includes various
orders like Coleopteran Order, Dipteran Order, Lepidopteran Order,
Hymenopteran Order, Hemipteran Order, Dictyopteran Order and
Orthropteran Order. Simply, it includes flies, ants, bees, cockroaches,
beetles, grasshoppers, etc. An adult member of this class contains three
pairs of leg, a segmented body which includes a head, thorax, abdomen
and one pair of antennae. They usually have compound eyes. They are the
only invertebrates with the ability of flight, and therefore many of
these insects also bear wings on them.
Poriferan Phylum – This
phylum mainly consists of sponges which are mainly marine animals. They
are considered to be very simple type of animals. These are deprived of
true tissues. They are mainly radically symmetrical. They do not
possess digestive tract and also lack the gastrula stage. There are
nearly 5000 to 10000 known species of sponges which primarily eat
floating organic particles and plankton.
Cnidearian Phylum – It
includes animals like jellyfish, sea anemones, etc. which are mostly
aquatic or live in marine type of environment. It contains nearly 9000
species. They are mostly found in marine habitats in comparison to fresh
water. They all possess a specialized type of stinging cell organelle.
The body can be either in the polyp or medusa form.
Mullusc Phylum – It
consists of Classes Gastropod, Cephalpod and Bivalvian. It means it
includes snails, slugs, squids, octopi, clams, oysters, etc. The word
Mollusks means soft of the body. They are bilaterally symmetrical and
body consists of more than two cell layers. They possess a body without
cavity. Their body can be divided into three parts mainly – head,
visceral hump and foot.
Annelid Phylum – Segmented
worms fall in this group. They are bilaterally symmetrical and
vermiform. Their body can be divided into three parts – a prosomium, a
trunk and a pygidium. They feed on various types of materials. They also
possess a true closed circulatory system. They generally prefer to live
in aquatic environment, however there are many terrestrial species also
included in this group.
Chordate Phylum – This phylum includes all animals
that bear a hollow nerve cord and a notochord, which is a flexible rod
which exits between the nerve cord and the digestive text. It contains
nearly more than 43000 species. Most of these species belong to the
subphylum Vertebrata. It includes important classes like -
Reptile Class – It includes animals like turtles, crocodile,
lizards, snakes, etc. These animals are fully terrestrial. They have no
larval stages and no metamorphosis.
The word has been taken from Italian word meaning creeping. It
consists of cold blooded animals. These reptiles have well developed
lungs right from the beginning of their birth. Except crocodiles, all of
the reptiles contains four chambered hearts.
Amphibian Class –
The word Amphibian refers to double life or both sided life (survive on
water as well as land). Frogs, toads and salamanders are examples of
amphibian. They do not have well developed lungs and possess toes but
without claws. Their heart is three chambered. They are cold blooded
animals. They hibernate for a very long time which can even last for
several months. They usually feed on exuviated skin.
Avain Class –
It is also known as Aves class. It includes all birds. Birds are warm
blooded animals with hollow bones and feathers. They are born from hard
shelled eggs. It includes gulls, songbirds, fowl, etc. Their feathers
and ability to fly is what makes them different from other types of
chordates. They have feathers like down feathers, filoplumes, contour
feathers or quill feathers.
Chondrichthye Class
– It consists of nearly 600 species of rays, sharks, and ratfish. The
main characteristics of Chondrichthyes are that they have no lungs and
swim bladder. Their skin is covered by placoid scales and mucous glands.
They possess true jaws and true teeth. They are oviparous or
viviparous.
Actinopterygii Class – This
class consists of ray finned fishes. They possess fins which are
actually webs of skin and are assisted by bony or horny spines. They are
found in marine and freshwater. Tradionally, they are classified into
two subclasses namely - Chondrostei and Neopterygii.
Mammalian Class – It
consists of warm blooded animals. They possess four chambered heart.
Hair of the mammals are composed of keratin. They possess teeth which
are imbedded in jaw bone. They are also known for possessing well
developed brain. The word mammalia has been derived from the Latin mamma
("teat, pap"). They are viviparous which means that young ones are born
alive. It comprises of both aquatic and terrestrial types. Some of the
mammals are also aerial. It includes dogs, cats, kangaroos, whales,
bats, rabbits, horses, moles, monkeys, human, elephants, mice, etc