Zoology & Animal Kingdom

Zoology & Animal Kingdom

Scientific study of the structure, form and distribution of animals called Zoology. John Ray was the scientist who developed key for identification of animals.

Classification of Animal Kingdom

The animal kingdom of the world is divided into two sub-kingdoms:

(A) Non Chordata

(B) Chordata

(A) Non Chordata

1. Unicellular Animal (Protozoan)

• Unicellular animals are kept in a single phylum Protozoa.

2. Multi-cellular Animal (Metazoan)

• Multi-cellular animals are divided into 9 phylums.

Classification of Animals According to Storer and Usinger

A. Phylum Protozoa

Main Features:

• Unicellular

• Its body is made of only one cell.

• There may be one or more nuclei in its cytoplasm.

• It is parasitic or free living.

• All metabolic activity (Intake of food, digestion, respiration, excretion, reproduction) takes place in unicellular body.

• Respiration and excretion take place by diffusion.

Example: Amoeba, Euglena, Trypanosoma etc.

B. Phylum Porifera

Main Features:

• All the animals of this group are found in marine water & bear pores on body.

• These are multicellular animals but cells do not make regular tissues.

• Numerous pores known as ostia found on body wall.

• Skeleton is made up of minute calcareous or silicon spicules.

Example: Sycon, Sponge etc.

Note: Sponges are also used as sound absorber.

C. Phylum Coelenterate (Cnidaria)

Main Features:

• Coelenteron is present inside body.

• First tissue grade organisation is found.

• Animals are aquatic and diploblastic.

• Around the mouth some thread-like structure are found known as tentacles, which help in holding or catching the food.

• Body radial symmetry.

• Specialized cnidoblast cell are found help in catching the prey which is used as food.

Example: Hydra, Jelly fish, Sea Anemone etc.

Note: Hydra reproduce by budding asexualy.

D. Phylum Platyhelminthes

Main Features:

• Flat worm

• Triploblastic with no body cavity.

• Dorso-ventraly flattened animal.

• Alimentary canal with single opening, anus absent.

• Excretion takes place by flame cells.

• They have no skeleton, respiratory organ, circulatory system etc.

• These are hermaphrodite animal.

Example: Planaria, Liver fluke, Tape worm etc.

Note: The disease Teeniasis is caused by parasite tape worm consuming undercooked food.

E. Phylum Aschelminthes

Main Features:

• Round worm

• Long, cylindrical, unsegmented worm.

• Bilaterally symmetrical and Triploblastic.

• Alimentary canal is complete in which mouth and anus both are present.

• There is no circulatory and respiratory systems but nervous system is present.

• Excretion takes place through Protonephridia.

• They are unisexual.

• Most form are parasitic but some are free living in soil and water.

Example: Round worm like – Ascaris, Thread worm, Wuchereria etc.

Note:

1. Ascaris causes disease Ascarisis in human. It is found in small intestine of man.

2. Enterobius (pin worm) – It is found mainly in the anus of child. Children feel itching and often vomits. Some children urinate on the bed at night.

3. Filarial disease is caused by Wuchereria bancrofti.

F. Phylum Annelid

Main Features:

• Annulus body Bearing ring like structure.

• Body is long, thin, soft and metamerically segmented.

• Locomotion takes place through Setae made up of Chitin.

• Alimentary canal is well developed.

• Normally respiration through skin, in some animals it takes place through gills.

• Nervous system is present and blood is red.

• Excretion by nephridia.

• The true coelom is present.

• Both unisexual and bisexual.

Example: Earthworm, Nereis, Leech etc.

Note:

• There are four pairs of heart in earthworm (not rue heart).

• Earthworm and millipedes are detritivores.

G. Phylum Arthoropoda

Main Features:

• Jointed leg

• Body is divided into three parts – Head, Thorax and Abdomen.

• Body is covered with a thick chitinous exoskeleton.

• Jointed leg.

• Circulatory system is open type.

• Its body cavities is called haemocoel.

• Trachea, book lungs, body surface are respiratory organ.

• These are mainly unisexual and fertilization takes place inside the body.

• Arthropods exhibited bilateral symmetry.

Example: Cockroach, prawn, crab, bug, fly, mosquito, bees etc.

Note:

• Number of eyes found in bee are five.

• Arthoropoda is the largest phylum of Animalia.

• There are six feet and four wings in insects.

• There are 13 chambers in the Cockroach’s heart.

• Ant is a social animal which lives reflects labor division.

• Termite is also a social animal which lives in colony.

• The main excretory organ of insects are malpighian tubules.

• Silk is obtained from pupa of silkworm.

• Cockroach has white blood due to lack of pigment, known as hemolymph.

H. Phylum Mollusca

Main Features:

• Soft bodies animal

• Body is soft divided into head and muscular foot.

• Mantle is always present in it, which secretes a hard calcareous shell around body.

• Alimentary canal is well developed.

• Respiration takes place through gills or ctenidia.

• Blood often has a blue colour respiratory pigment called hemocyanin.

• Excretion takes place through kidneys.

Example: Pila, Octopus, Loligo, Squid etc.

Note:

• Mollusca other name in vogue:

  • Aplysia – Sea rabbit

  • Doris – Sea lemon

  • Octopus – Devil-fish

  • Sepia – Cuttle-fish

• Octopus have more than one heart.

• Haliotic belong to phylum Mollusca.

• Hemocyanin is an oxygen transport metalloproteinase containing two atoms of copper found in the blood of Mollusca.

• Mollusca is the second largest phylum of Animalia.

• The largest spineless invertebrate creature in the world is colossal squid by weight. On the bases of size Giant squid is the largest spineless invertebrate comes under Mollusca.

I. Phylum Echinodermate

Main Features:

• Spiny skin

• All the animals of this group are marine.

• Water vascular system is present.

• There is Tube feet for locomotion & taking food which works as sensory organ.

• Brain is not developed in nervous system.

• There is a special capacity of regeneration.

Example: Star fish, Sea urchin, Sea cucumber, Brittle starts etc.

Note: The function of the Aristotle lantern is to chew the food. It is found in sea urchin.

G. Phylum Chordata

Main Features:

• Notochord is present.

• All chordates are triploblastic, coelomae and bilaterally symmetrical.

• A dorsal hollow tabular nerve cord and paired pharyngeal gill slits are other features of chordates.

According to classification there are two subphyla in Chordata:

(a) Protochordates

(b) Vertebrata

Some Main Groups of Phylum Chordata

1. Pisces

Main Features:

• Aquatic life

• All are cold blooded animals.

• Its heart only pumps impure or deoxygenated blood. Heart is made up of two chambers.

• Respiration takes place through gills.

Example: Labeo, Scoliodon (Dog fish), Torpedo (Electric ray), Exocoetus (flying fish), Hippocampus (Sea horse) etc.

2. Amphibian

Main Features:

• Found both on land & water

• All these creatures are amphibian.

• All these are cold-blooded.

• Respiration takes place through gill, skin and lungs.

• Heart has three chambers, two auricles and one ventricle.

Example: Frog, Necturus, Toad Icthyophis, Salamander etc.

Note:

• During hibernation frog respire through skin.

• In fact the croaking of frogs is the call for sex.

• Salamander has three chambered heart which belong to the phylum Amphibia.

3. Reptilia

Main Features:

• Crawllling animal

• Land vertebrate, cold-blooded, terrestrial or aquatic vertebrates.

• It contains two pair of limbs.

• The skeleton is completely flexible.

• Respiration takes place through lungs.

• Eggs are covered with shell made up of Calcium carbonate.

Example: Lizard, snake, tortoise, crocodile, sphenodon etc.

Note:

• Mesozoic era is called the era of reptiles.

• Cobra is the only snake which makes nests.

• Cobra emits their venom through fangs.

• Heloderma is the only poisonous lizard.

• Sea snake which is called Hydrophis is the world’s most poisonous snake.

4. Aves

Main Features:

• Warm blooded tetrapod vertebrates with flight adaptation.

• Its fore-feet modified into wings to fly.

• Boat shaped body is divisible into head, neck, trunk and tail.

• Its respiratory organ is lungs.

• Birds have no teeth. Beak help in feeding.

• Beak is formed by jaw.

• Pneumatic bones are an important characteristics of Aves.

Example: Crow, Peacock, Parrot etc.

Note:

1. Flightless Birds – Kiwi and Emus.

2. Largest alive bird is Ostrich.

3. Smallest bird is Humming bird.

4. Largest zoo in India is Alipur (Kolkata) and the largest zoo of the world is Cruiser National Park in South Africa.

5. Coppersmith Barbet is a bird with well-patterned face of bright colour.

5. Mammalia

Main Features:

• Sweat glands and oil glands are found on skin.

• All these animals are warm blooded.

• Its heart is divided into four chambers.

• Tooth comes twice in these animals. (Diphyodont)

• There is no nucleus in its red blood cells (except in camel and lama).

• Skin of mammal have hair.

• External ear (Pinna) is present in mammal.

Mammals are divided into three sub-classes:

1. Prototheria – It lays eggs. Example – Echindna

2. Metatheria – It bears immature child. Example – Kangaroo

3. Eutheria – It bears well developed child. Example – Human

Example: Dolphin is an example of class mammal. Group of Dolphin is called Pod.

Note:

• In mammal the highest body temperature is of goat. (Average 39 degree celsius).

• Echindna and Duck billied Playpus are the egg lying mammal.

• Ctenophora a phylum of invertebrate animals are also known as combjellies.

• PH range of human body is between 7.35 to 7.45.

• Allantois of mammalian embryo help in respiration.

• Excretion in hemichordate takes place by glomerulus.

• Smallest man like ape is Orangutam.

• Man belong to the family of ‘Hominidoe’.

Scientific Names of Common Animals

Note: Honeybees perform waggle dance for others of their kin to indicate the direction and the distance to a source of their food.

Final Thoughts

Zoology is the scientific study of animal structure, form, and distribution. The animal kingdom is broadly divided into Non-Chordata and Chordata.

Non-Chordates include simple organisms like Protozoa, Porifera, Coelenterata, Platyhelminthes, Annelida, Arthropoda, Mollusca, and Echinodermata, while Chordates include advanced groups such as Pisces, Amphibia, Reptilia, Aves, and Mammalia. Each group shows unique features in body design, symmetry, and reproduction.

Scientists like John Ray contributed to early animal classification and identification. From tiny Amoeba to majestic Tigers, Zoology helps us understand how all living creatures are interconnected within the vast diversity of life on Earth.