XI Biology - Chapter 10 - Kingdom Anamalia

Classification of Kingdom Anamalia
The classification or grouping of animals is called Taxonomy or Systematics, primarily on the basis of their evolutionary relationships.
Major phyla of kingdom Animalia are as follows



Phylum Porifera (Sponges)
Word Porifera is derived from Latin Porus – Pores and Ferro – to bear. The animals are also called “Sponges”.
MAIN CHARACTERISTICS
Animals of this phylum show following important characters.




NATURE
Most simple multicellular organisms. From evolutionary point of view they occupy a position between protozoa and true metazoa




HABIT AND HABITAT
Mostly marine but few in fresh water habitat.
They are sessile, living attached to rocks, coral and other hard surfaces



SHAPE AND STRUCTURE
Their shape may be cylindrical, branching, globular, flat, bell shaped or cup shaped
Some are dull in colour and most are brightly coloured
The body is perforated by pores and canals



MICROSCOPIC STRUCTURE
Most of sponges contain following types of cell:

(A) PINACOCYTES
Forming the epidermis.

(B) POROCYTES
Form pores of the body wall

(C) CHOANOCYTES
These are flagellated cells, form the internal lining of the body. These cells are strikingly similar to the choano flagellates.

Much of the body is composed of jelly like matrix containing a skeleton made of Protein, CaCO3 or silica.
Sponges are organized on cellular level, instead of a single cell carring on all the life activities.
Sponges show cellular differentiation but little or no coordination of cells to form tissues.
They usually have an endoskeleton of separate spicules.
They do not posses a head, an interior end, a mouth or gut cavity.
They are sedentary organisms ranging in size from 1 to 200cm.



DIGESTION
Digestion takes place with in the cell. (Intracellular)

PROCESS OF FEEDING, EXCRETION AND RESPIRATION

Sponges feed by filtering out bacteria and fine particles of organic matter from water.
The flagella of “Choanocytes” beat and create a current of water.
The water current also helps in respiration, removal of waste products and dispersal of gametes.



REPRODUCTION
Reproduction is of both type asexual and sexual
Asexual reproduction is by means of “Buds” and “Gemmules formation”.
Sexual reproduction is by means of sperm and ova.
All sponges appear to be diploid and have the usual metazoan process of “Oogenesis” and “Spermatogenesis”.
The eggs retained just beneath the choanocytes where they are fertilized by sperm from another sponge brought in with the current of water.
Fertilization is internal.



LARVA
After cleavage, the larva escape from the parent to the open sea as a free swimming “Amphiblastula larva”.
It finally becomes attached to the bottom by its anterior end.
Reproduction is also by fragmentation.



BODY CAVITY
Body cavity is known as “Spongocoel”.




EXAMPLES
Common examples are

1. Sycon

2. Euplectella

3. Euspongia






Phylum Cnidaria (Coelenterata)
This phylum include such simple animals having only two body layers. Hence these are called DIPLOBLASTIC
MAIN CHARACTERS
HABIT AND HABITAT
They are aquatic animals, mostly marine and few fresh water forms. They are sedentary or free swimming and solitary or colonial




STRUCTURE
The cnidaria are metazoa having the simplest type of body wall consisting of two layers. The outer epidermis and the inner gastrodermis which lines the body cavity.
In between the two layers lies the mesogloa, non-cellular jelly secreted by them.
Cnidarians, due to their two layers body wall are termed as diploblastic animals. All other metazons possesses a third layer called mesoderm in their body wall, laying in between the epidermis and gastrodermis (Endoderm) and are therefore called Triploblastic animals.
They have radially symmetrical body plan organized as a hollow sac.
The mouth is surrounded by a circle of tentacles bearing cnidoblasts stinging cells containing nematocysts.
They have central digestive cavity connected to the outside by mouth.
STRUCTURAL TYPES
The Cnidarians are radially symmetrical and occur in two types of forms.

(a) The polyp

(b) The Medusa

(A) POLYP
The polyp like Cnidarian for example sea anemone has a cylindrical body with a mouth directed upwards and surrounded by tentacles. The basal surface of the body is attached to the substratum.

(B) MEDUSA
The medusa like Cnidarians jelly fish are umbrella like in appearance. Their oral surface, bearing the mouth is directed downwards. Whereas the aboral surface is directed upward. The medusoid Cnidarians are usually free swimming.




PROCESS OF FEEDING AND DEFENCE
The Cnidarians feed mostly on animal diet.
The food is digested in the gut and the waste products are expelled through the mouth.
The Cnidarians so named, because they possess cnidoblasts bearing nematocysts which help in feeding and defence.



REPRODUCTION
The Cnidarians reproduce by asexual as well as sexual methods. Polypoid Cnidarians possess a remarkable ability to regenerate.

(A) REGENERATION
If the oral part of the body is lost. The remaining part regenerates the new mouth and the whole of tentacles.

(B) ASEXUAL REPRODUCTION
A sexual reproduction takes place by Budding.

(C) SEXUAL REPRODUCTION
The sexual reproduction takes place through male or female gametes which are usually produced by different parents.
The gametes develop in the interstitial cells and aggregate in gonads which are located either in the epidermis or in the gastodermis.
The fertilized egg gives rise to “Planula Larva”



CLASSIFICATION OF CNIDARIA (COELENTERATA)
The Phylum Cnidaria is divided into three classes:

1. Hydrozoa

2. Scyphozoa

3. Anthozoa

1. HYDROZOA
As the most primitive class of the Cnidarians, Hydrozoa is thought by some evolutionists to have given rise to both other classes. They show following characteristic features:

They are mainly marine, but some are fresh water species
Many species have both polyp and medusa
For e.g:

Hydra, Obelia and Physalia

2. SCYPHOZOA
Most of animals of this class are commonly called “Jelly Fish”.
They are semitransparent and are of various colours.
Most are of marine habitat.
For e.g:

Aurelia and Cyanea (largest Jelly Fish)

3. ANTHOZOA
These animals are mostly marine.
Solitary or colonial Polyp forms are present.
Medusa stage is absent.
Gastrovascular cavity is divided into chambers, increase area for digestion.
For e.g:

Sea-anemones and Corals etc







Phylum Platyhelminthes (Flat worms)
The term Platyhelminthes is derived from Greek Platy – flat and Helmenthes – worms. This Phylum include Flat worms
MAIN CHARACTERS
HABIT AND HABITAT
Animals are mostly Parasitic in habitat and found in other higher animals. But some animals are also free living.




NATURE
They are triploblastic in nature i.e. body is composed of three germinal layers, viz, ectoderm, mesoderm and endoderm




EXTERNAL FEATURES
Their bodies are compressed dorsoventrally and shows bilateral symmetry.
Body shape generally worm like but vary from moderately elongated flattened to long flat ribbons and leaf like.
The flat worms are small to moderate in size varying from microscopic to as long as up to 10-15 m.
Majority of animals are white or colourless, some derive colour from ingested food.
Anterior end of body is differentiated into head.
Ventral surface bearing mouth and genital pores.
Presence of great variety of adhesive parts e.g. suckers.
Body is covered by cuticle or by ciliated epidermis.
Hard part consist of cuticle, spines, thorns or hooks etc.



INTERNAL FEATURES
Endo and Exo skeleton are completely absent, hence the body is generally soft.
Acoelomate i.e. true coelom is absent.
Body space between various organs is filled with MESENCHYME.
Digestive system is poorly developed or absent.
Respiratory and Circulatory systems are absent.
Excretory system consists of Protonephridia or flame cells.
Nervous system is primitive. The main nervous system consists of a pair of cerebral ganglia or brain and 1-3 pairs of longitudinal nerve cords, connected to each other by transverse commissures.



REPRODUCTION
Platyhelmenthes are hermaphrodite i.e. male and female sex organs are present in same individual.
In majority of forms eggs are devoid of Yolk but provided with special yolk cells.
Cross fertilization as well as self fertilization is present.
Life cycle may be simple or complicated involved one or more hosts.



EXAMPLES
Planaria, Liver flukes, Schistosoma and Taenia Solium etc.








Phylum Aschelminthes (Nematoda/Round worm)
Nematoda are called Pin worm or round worms.

MAIN CHARACTERS
HABIT AND HABITAT
Nematoda have a very wide distribution and they seem to have mastered almost every habitat.
Free living nematodes are found in the sea, fresh water or in the soil in all kinds of environment.
There are also many Parasitic nematodes found in all groups of Plants and animals.
The Saprophagous species live in decomposing plant and animal bodies and in rotting fruits.



NATURE
They have a bilaterally symmetrical, cylindrical body, glistening smooth surface. They are triploblastic.




EXTERNAL FEATURES
They show no trace of segmentation.
Most of the free living nematodes are less then a millimeter length.
Some of the parasitic species attain a length of several meters e.g. Guinea worm (Dracunculus medinensis).
They are usually long, round, tapered at both ends showing very little morphological diversity from species to species.
The mouth of nematodes is modified for various modes of feeding such as cutting, tearing, piercing and sucking fluids from the host.
Body is covered by cuticle, which moults only during the period of growth.



INTERNAL FEATURES
The organs are packed in parenchyma when young, but later on it disappears in adult. So that organs lie in a fluid filled cavity. This cavity is termed as PSEUDOCOEL and it has not peritoneum.
Muscles are only longitudinal.
Excretory system has no flame cells.
Alimentary canal is straight with ectodermal fore and hind gut and an endodermal mid gut.



REPRODUCTION
Sexes are generally separate.
Gonades are tubular and continues with their ducts.
Female organs are usually paired and open by vulva.
Male organs are single and open into a cloaca.
The life cycle of Parasitic species involves one, two or more hosts



EXAMPLES
Ascaris (Round worms), Hookworms and Thread worms etc.






Phylum Annelida (Segmented worms)
The word Annelida is derived from latin Annelus meaning little ring.

MAIN CHARACTERS
NATURE
Annelida are triploblastic, symmetrical, coelomata and segmented metozoa.




HABIT AND HABITAT
Annelida are mostly aquatic, marine or fresh water, burrowing or living in tubes, some free living forms.




EXTERNAL FEATURES
The most important feature of annelida is their metameric segmentation. (External segmentation)
Segmentation is indicated externally by circular constrictions or grooves on the body wall.
Outer covering of the body is cuticle secreted by the underlying epidermis.
Appendages, when present are unjointed.
Locomotory organs are segmentally arranged, paired setae or chaetae.



INTERNAL FEATURES
Body wall is contractile, consists of an outer epidermis, circular and longitudinal muscles.
The gut, longitudinal blood vessels and the nerve cord extend throughout the body length, whereas other structures are repeated in each segment.
Important character of annelida is the development of series of coelomic compartments in their body between the gut and the body wall.
The Coelom is a cavity, which develop within the mesoderm and is lined by mesodermal cells.
Segmented musculature plays an important part in locomotion of Annelids.



SYSTEMS OF BODY
Alimentary canal is tube like extending straight from mouth to anus.
Respiration through general body surface, by gills in some forms.
Blood vascular system is closed type.
Blood is red due to haemoglobin.
Excretory organs are Nephridia usually one pair in each segment.
Nervous system consists of dorsal brain and longitudinal ventral nerve cord.
Sexes may be united or separate.
Development is direct when sexes are united and indirect when sexes are separate.



EXAMPLES
Nereis, Earthworm and Leeches etc.




CLASSIFICATION OF PHYLUM ANNELIDA
Phylum Annelida is divided into four classes:

1. Polychaeta

2. Oligochaeta

3. Hirudinea

4. Archiannelida




1.POLYCHAETA
LOCOMOTORY ORGANS

The Polychaetes possess paired parapodia functioning as locomotry appendages, are present only in the class Polychaeta.

PROSTOMIUM

Usually there is a distinct head or Prostomium bearing sensory and feeding appendages.

MODE OF LIFE

The Polychaetes may be carnivorous, scavengers, or filter feeders.

REPRODUCTION

The sexes are separate and fertilization of eggs takes place outside body. Their free swimming larva is called Trochophore.

RESPIRATION

The respiration takes place through the body surface in many but in some gills may be present as respiratory organs.

EXAMPLES

Some well-known examples of marine polychaetes are Nereis, Arenicola and Sabella. Nereis lives beneath stones and in crakes of rocks.




2.CLASS OLIGOCHAETA
LOCOMOTORY ORGANS

The Oligochaetes possess fewer numbers of Setae as compared to the Polychaetes. The setae help the earth worms in crawling.

SENSE ORGANS

There anterior end lacks eyes, or sensory appendages.

CLITELLUM

At sexual maturity, all of the oligochaetes develop in several segment, glandular epithelium, called clitellum.

MODE OF LIFE

Oligochaetes live either in fresh water or on land.
There is no free swimming larval stage in their development
Majority of oligochaetes are scavengers, feeding on decomposing organic matter.
Some fresh water species feed on algae.
Burrowers like earth worm ingest a large quantity of soil, digest the organic matter and the living fauna.
RESPIRATION

Respiration takes place through their general body surface. Some aquatic species possess anal gills.

ECONOMIC IMPORTANCE

Earthworms increase the fertility of soil by physically over turning it. They ingest the soil, break it down and deposit it in the form of casts. The over turned soil is relatively in proportions of total nitrogen, organic carbon, calcium, magnesium and phosphorus.




3.CLASS HIRUDINEA
BODY SEGMENTS

Unlike polychaetes and oligochaetes, the number of body segment in leeches is fixed at 34.

SUCKERS

The anterior and posterior body segments are fused to form suckers.

LOCOMOTION

Leeches either swim or crawl.

RESPIRATION

Respiration generally takes place through the body surface. Leaf like gills may be present.

PARASITIC NATURE

Most leeches feed by sucking blood of aquatic invertebrates and vertebrates.




4.ARCHIANNELIDA
It is a small group of marine worms.
They are not segmented externally and don’t have bristles.
They live in the sea and show annelid characteristics to a minor extent.
Their development is also characterized by Trochophore Larva.
EXAMPLES

Nerilla
Dinophilus






Phylum Mollusca (Shelled Animals)
Mollusca is the second largest phylum of the animal kingdom, and include Slugs, Clams, Scallops and Squids.

MAIN CHARACTERS
HABIT AND HABITAT
The majority of molluscs are marine. Some snails and clams inhabit fresh water while slugs are terrestrial.




NATURE
Molluscs are primitively bilaterally symmetrical animals.
Some molluscs serve as intermediate host of helminthes parasites and some are destructive to wooden bottom of ship.



EXTERNAL FEATURES
The body is soft, unsegmented and consists of head, foot, mantle and visceral mass.
The body is clothed with a one layered epidermis.
Body is commonly protected by an exoskeletal calcerous shell of one or more pieces, secreted by Mantle.
Head is distinct, bearing the mouth and provided with eyes, tentacles and other sense organs.



INTERNAL FEATURES
Visceral mass contains the organs of the body in compact form.
Body cavity is hoemocoel.
Digestive system-tract is simple.
Circulatory system is open.
The mouth in many species possesses a radulla, (a tongue like structure) that can be protruded to scrape, tear or pull food.
The respiration is by means of gills or lungs.
The nervous system consists of cerebral ganglion, a pair of pedal cords to the foot and a pair of visceral mass.



REPRODUCTION
Molluscs may have separate sexes or they may be hermaphrodite.
The fertilized eggs give rise to a larva stage which transform into adult.
Three types of larva trochophore, veliger and glochidium occur in molluscs.



CLASSIFICATION OF MOLLUSCA
The phylum Mollusca is divided into six classes:

1. Amphineura

2. Scaphopoda

3. Gastropoda

4. Bivalvia

5. Cephalopoda

6. Monoplacophora




CLASS GASTROPODA
EXAMPLE

This is the largest class of mollusca which included Snails, Whelks, Conchs, Limpets, Cowries and Slugs.

CHARACTERS

The gastropods are mostly marine, though some live in fresh water and a few are terrestrial.
The gastropods are asymmetrical.
They have a well developed head and a broad muscular foot.
Both are on the ventral side of their body.
Their visceral organs are located on the dorsal side and are enclosed in a one piece shell which is spirally coiled.
The gastropods use the redula to scarp food particles or to drill holes in the shells of bivalves.
Some are carnivorous, a few are filter feeders.



CLASS BIVALVIA
The class Bivalvia is the second largest class of the Phylum Mollusca.
The bivalves are bilaterally symmetrical with a laterally compressed body enclosed in a shell of two pieces (valves) hinged together.
The shell can be opened or closed.
By closing the shell tightly, the animals can protect it self off from unfavourable environment or saves itself from predators.
The head is rudimentary and the radula is absent.
The foot is ventral, laterally compressed, usually wedge shaped.
EXAMPLE

Bivalves include the Clams, Mussels, Oysters and Scallops. They are mostly marine some live in fresh water but none is terrestrial.

PEARL FORMATION

When a foreign particle living or dead enters a bivalve it causes irritation.
The epithelial cells of the mantle start depositing concentric layers of calcerous material around it, which ultimately forms a pearl.
Pearl culture has been successfully carried out by artificially introducing fragments of man made hard material in pearl oysters.
Pearls are formed both in marine as well as fresh water species.



CLASS CEPHALOPODA
The cephalopods are all marine and exhibit a high level of development.
Nautilus is the only living cephaloped that possesses a well developed external shell which is coiled and divided by transverse Septa in chambers.
The shell is reduced and overgrown by mantle in Squids and Cuttle fish.
It is completely absent in Octopus.
EXAMPLES

Nautrilords, Squids, Cuttle fish, Octopus etc.




CLASS MONOPLACOPHORA
They are primitive molluscs with a long fossil record.
They have only one living representative, Neoporlina, which retains the segmented characteristics of annelids, lost in all other molluscs.






Phylum Arthropoda (Jointed Appendages Animals)

MAIN CHARACTERS
Arthropoda is the largest Phylum of the animal kingdom including 10, 00000 species of different types of animals.
The word Arthropods is derived from Greek Arthos – Jointed and Podos – Foot.



HABIT AND HABITAT
Arthropodes have undergone an adaptive radiation for aerial, aquatic, terrestrial and parasitic environment. They are widely distributed in each and every place of the world.




NATURE
Arthropoda are “bilaterally symmetrical,” metamerically segmented metazoa.



EXTERNAL FEATURES
Their body is covered by an exo-skeleton of “chitin” and protein.
They possess paired jointed appendages.
Their metamers are not alike but are specialized and their number is generally fixed.
The head is well developed.



INTERNAL FEATURES
Musculature is not continues but comprises separates striped muscles.
The coelomic space in Arthropods is occupied by the blood vascular system and is thus called “Haemocoel.”
Digestive tract is complete; mouth and anus lie at the opposite end of the body.
Circulatory system is open with dorsal heart and arteries but without capillaries.
Respiration through general body surface, by gills in aquatic forms, trachea or book lungs in terrestrial forms.
Excretion by “Malpighian tubules” or Coelomoducts.
Sexes are generally separate and sexual dimorphism is often exhibited by several forms.
Fertilization is internal.
Development is usually indirect through the larval stage.
Nervous system of arthropods is quite similar to that of annelids and consists of dorsal anterior brain and a double ventral nerve cord.



CLASSIFICATION OF ARTHROPODA
Phylum Arthropoda is divided into following five classes:

1. CLASS MEROSTOMATA
Almost all members of the class Merostomata are extinct. The only living merostomes, the king Crabs have survived.
The animals are horse-shoe shaped.
The long spike like tail that extends, posteriorly is used in locomotion. It is called “Telson.”
They feed on mollusks, worms and other invertebrates that they find on the ocean floor.
King Crabs a hors-shoe crabs have a tough “Carapace” jointed to a smaller abdomen.
E.g:Limulus Polyphemus (King Crab).



2. CLASS ARACHNIDA
This class includes spiders, scorpions, mites, ticks and many other terrestrial arthropods.
The Arachnid body consists of a cephalothorax and abdomen.
Cephalothorax is comprised of fused head and thorax.
Arachnids have six pairs of jointed appendages.
Most Archnids are carnivorous and prey upon insects and other small arthropods.
Respiration in archnids takes place either by trachea or book lungs or by both.
They are mainly terrestrial arthropods.
They have no antenna.
Cephalothorax is non-segmented.
E.g: Scorpions, Ticks & Mites, Spiders



3. CLASS CRUSTACEA
They live both in marine and fresh waters.
A few are terrestrial.
Crustaceans are unique among arthropods in possessing two pairs of antenna.
They always have one pair of mandibles and two pairs of maxillae around the mouth.
Mandibles are usually adapted for biting and chewing. Maxillae are used for holding the food.
Their body is divided into three distinct parts, i.e. the head, thorax and abdomen.
Respiration usually takes place through gills associated with appendages.
The sexes are usually separate and the reproduction is sexual.
The thoracic and abdominal appendages may be variously modified for walking, swimming, feeding, respiration or as accessory reproductive structures.
E.g: Sacculina (Parasitic Crustacean), Astacus (Cray-fish), Prawns, Shrimps, Lobsters and Crabs etc.

4. CLASS MYRIAPODA
All the animals are terrestrial.
Their body is divided into a head and an elongated trunk with many segments.
Each segment bears one or two pairs of legs.
They are carnivorous /herbivorous.
Eyes may present or absent.
E.g: Millipedes and Centipedes etc.



5. CLASS INSECTA (HEXAPODA)
Insecta is the largest class of the animal kingdom.


HABIT AND HABITAT

In their adaptive radiation, approximately a 8,50,000 species of insecta have occupied all types of terrestrial habitat.
Some live in fresh water, however one small group is marine.

NATURE AND ADAPTATIONS

The great success of insects can be attributed partly to the development of flight in them.
Flight has provided them the great capacity of dispersal, access to food sources, and favourable habitat and escape from enemies.
Corresponding to their number of species, there exists a huge variation in their structural and biological adaptations.

EXTERNAL FEATURES

All insects have their body divided into three well-defined regions i.e. the head, thorax and abdomen.
There is always a pair of antenna on the head.
The thorax always consists of three segments:
(a) Prothorax

(b) Mesothorax

(c) Metathorax

Each thoracic segment bears a pair of legs.
Head consists of six fused segments and a pair of compound eyes and mouth parts.
Abdomen comprises 7-11 segments and devoid of appendages.
MOUTH PARTS

The feeding appendages consists of three pairs:
(a) Mandibles

(b) First Pair of Maxilla

(c) Second Pair of Maxilla

The second pair of maxillae have fused together to form the “LABIUM,” or lower lip
The upper lip is formed by the projections head and is called the “LABRUM.’
Types:- The mouth appendages have been greatly modified to form five basic types of pattern:
(i) Biting

(ii) Chewing

(iii) Piercing

(iv) Sucking

(v) Siphoning or Sponging


INTERNAL FEATURES

Heart is elongated, tubular and divided into chambers situated in the abdomen.
Excretion takes place through “Malpighian tubules.”
Liver is absent but salivary glands are usually present.
Respiration is by “TRACHEA”. External gills may be present as accessory respiratory organs in some aquatic insects.

REPRODUCTION

Reproduction is sexual in most insects. However it takes place parthenogenetically i.e. eggs developing without being fertilized by sperms in a number of insects e.g: Aphids and Termites etc.

METAMORPHOSIS

The development of insects after hatching from egg into adult stage involves considerable growth and in some cases drastic morphological changes.
The entire post-hatching development is termed as “Metamorphosis.”
(A) INCOMPLETE METAMORPHOSIS

In some insects the immature form that hatch from the egg are essentially similar in shape to their adults, but are smaller in size, lack wings and reproductive organs
They attain adult characters after some growth period. This type of metamorphosis is called “Incomplete Metamorphosis.”
Three stages are Egg → Nymph → Adult.
For example Cockroach, Grasshopper, Bugs etc.
(B) COMPLETE METAMORPHOSIS

In this type the animal shows following stages during its complete development: Egg → Larva → Pupa → Adult.
For example Mosquito, Butter fly, House fly etc.



ECONOMIC IMPORTANCE OF INSECTS
Insects are of very great importance to man.

BENEFICIAL INSECTS

1. Apis, the honey bees produce honey and also give wax.

2. Insects bring about the cross-pollination.

3. Bombyx and Eupterote are silk-moths and produce silk.

4. The larvae of Lucilla and Pharmia are used in wound healing of bones.

5. Some insects feed upon and destroy harmful insects.

6. Some insects are Scavengers

HARMFUL INSECTS

1. Many types of mosquitoes, flies, fleas, lice and bugs transmit diseases to man and animals.

2. Human food is spoiled by cockroaches, ants and flies.

3. Tinea and Teniola are cloth-moths and destroy cloths.

4. Tenebrio is mealworm. They eat meal, flour and grains.

5. Lepisma destroy the books.

6. Termites destroy books and wood.

7. Many insects injurious to crops e.g. Tree hoppers, Leaf hoppers, Aphids, White flies and bugs.








Phylum Echinodermata

GENERAL CHARACTERS
HABIT AND HABITAT
The Echinodermates are exclusively marine including the largest invertebrate “Giant Squids.”




EXTERNAL FEATURES
Symmetry usually radial, nearly always pentamerous.
Body shape is rounded to cylindrical or star like.
Surface of the body is rough.
Body wall consists of an outer epidermis, a middle dermis and inner lining of peritoneum.



INTERNAL FEATURES
Endoskeleton consists of closely fitted plates forming shell usually called “THECA,” may be composed of separate small “OSSICLES.”
Coelom is spacious, lined by peritoneum and occupied mainly by digestive and reproductive systems.
Presence of “Water Vascular System” is most characteristic feature.
Alimentary tract is usually coiled.
Circulatory or Haemal or blood lacunar system is typically present.
Excretory system is wanting.
Nervous system is primitive, consists of ganglionated nerve cord.
Sense organs are poorly developed.
Sexes are usually separate.
Reproduction is usually sexual, fertilization is external.



WATER CANAL SYSTEM
Water canal system is unique in possessing an internal closed system of canals containing a watery fluid.




REGENERATION
Regeneration of lost part is common




IMPORTANCE OF WATER CANAL SYSTEM
These canals are provided with tubular protrusions called “Tube Feet,” which serve a number of functions like locomotion, anchoring to hard surfaces, grabbing the prey, diverting food particles towards mouth and in some cases also respiration. The watery fluid is drawn from the surrounding water through a perforated disc called the “Madreporite.”




EXAMPLE
Star Fish, Brittle stars, Sea urchins, Sea-cucumbers, Sea-Dollar, Sea-lilies and Feather stars.




LARVA
Bipinnaria larva







Phylum Hemichordata

GENERAL CHARACTERS
It is a small group of animals, which include about 90 species.
They are soft-bodied animals, which usually live in shallow “U” shaped burrows in the sandy or muddy sea bottom.



EXTERNAL FEATURES
They are cylindrical or vase shaped animals, bilaterally symmetrical and lack any segmentation.
They may be solitary or colonial and usually range between a few millimeter and 250 cm in length.
Sexes are separate in hemichordates.



INTERNAL FEATURES
Circulatory system is open and coelom is divided into three chambers.
A dorsal and a ventral nerve cord are present.



LARVA
Tornaria larva




EXAMPLE
Balanoglossus, Acron worm etc.








Phylum Chordata
It includes animals, which exhibit great difference of anatomy, physiology and habits.
These animals are highly developed.

GENERAL CHARACTERS
The chordate animals at some time in their life history exhibit the following diagnostic characters:

1. NOTOCHORD
It is an elastic, solid, skeletal rod lying below the nerve cord and above the alimentary canal.
It serves as a primitive internal skeleton and acts as a rigid axis.
It may persist throughout life or it may be replaced partially or completely by a backbone or vertebral column.
2. DORSAL HOLLOW NERVOUS SYSTEM
There is a dorsal, hollow, fluid filled nerve cord.
It is formed by enfolding of a mid-dorsal strip of ectoderm and it generally sinks below the surface.
It lies above the notochord and outside the coelom.
It persists throughout life in most chordates, but in a few it degenerates before maturity.
3. GILL CLEFTS
These are paired openings leading from the Pharynx to the exterior.
Such gill clefts appear during the development of every chordate, but in many aquatic forms they are lined with vascular lemallae, which forms gills for respiration.
In terrestrial chordates, which never breath by gills, gill clefts are present during early development but later on, they disappear.
4. PHA-RYNGEAL POUCHES
All the chordates have paired pharyngeal pouches at some stage of their life cycle.
These extend from laterally from the anterior part of the digestive tract towards the body wall.
OTHER FEATURES
Chordates are triploblastic.
They are bilaterally symmetrical.
True coelom is found.
They are found in almost all the habitats of the World.



CLASSIFICATION OF PHYLUM CHORDATA
The Phylum Chordata is divided into two groups which are:

1. Acraniata (Protochordata)

2. Craniata (Vertebrata)




1. GROUP ACRANIATA (PROTOCHORDATA)
They are first or simple Chordates.
Brain box (Cranium) is absent and hence brain is not prominent.
Notochord does not transform into vertebral column.
This group is further divided into two sub-phyla, which are as follows:

a) Sub-Phylum Urochordata (Notochord in tail)

b) Sub-Phylum Cephalochordata (Notochord head to tail)

A) SUB-PHYLUM UROCHORDATA (NOTOCHORD IN TAIL)
They are also known as “Tunicates” because their body is enclosed in a sac called “Tunic.”
All members are marine and sessile.
Body possesses two openings, an incurrent or buccal siphon and an excurrent or Atrial siphon, through these openings exchange of gases and food or waste material take place.
As a result of “Retrogressive metamorphosis” the larva loses its tail and most of chordate characters and converts into an adult.
E.g: Ascidia, Herdmania etc.
B) SUB-PHYLUM CEPHALOCHORDATA (NOTOCHORD FROM HEAD TO TAIL)
This is a small group of marine animals, body with pointed ends.
Usually live buried in sand, in shallow water with anterior end protruded out.
They show all typical chordate characters (hollow dorsal nerve chord, pharyngeal gill slits and notochord).
Only two genera are present around the world.
E.g: Branchiostoma (Amphioxus) etc



2. GROUP CRANIATA (VERTEBRATA)
In these chordates brain is protected inside a skeletal brain box called “CRANIUM.”
Also known as “Vertebrates” because notochord is replaced by a vertebral column.
This group is sub-divided into two sub-phyla, which are as follows:

a) Sub-Phylum Agnatha (Mouth without Jaws)

b) Sub-Phylum Gnathostomata (Mouth with Jaws)




A) SUB-PHYLUM AGNATHA (MOUTH WITHOUT JAWS)
This is a small group of marine vertebrates also known as “Cyclostomes.”
Superficially they resemble the fish but lack the jaw so they are often known as “Jawless Fishes.”
They have rounded suctorial mouth with many rings of teeth.
Paired fins and scales on body.
Usually parasitic in nature.
E.g: Hag Fish, Lamprey etc.



B) SUB-PHYLUM GNATHOSTOMATA (MOUTH WITH JAWS)
It is a large group of vertebrates with both upper and lower jaw.
Teeth may be present or absent.
Gnathostomata are divided into two super classes, which are as follows:

i) Pisces (Fishes)

ii) Tetrapoda




I) SUPER CLASS PISCES (FISHES)
This is the largest group of chordates, which includes half of the chordate (25,000 species).
Study of fishes is called “Ichthyology.”
Body is streamlined with paired fins and covered over by dermal scales.
Super class Pisces is divided into two classes, which are:

i-a) Chondrichthyes (Cartilage Fishes)

i-b) Osteiochthyes (Bony Fishes)

I-A) CLASS CHONDRICHTHYES (CARTILAGE FISHES)

Alternate name is “Class Elasmobranchi.”
Usually includes marine fishes with endoskeleton of cartilage (soft bone).
Skin contains sharp tiny enamel coated denticles called “Placoid Scales,” which form exoskeleton.
· Mouth is ventral in position and tail fin is “Heterocercal.”
Five exposed gill slits, which are not covered over by a gill cover.
Common examples are Skates, Sharks, Rays and Scoliodon (Dog Fish)- a small Shark etc.
I-B) CLASS OSTEIOCHTHYES (BONY FISHES)

Alternate name is “Teleostom,” actually the largest class of chordates.
Includes marine and fresh water fishes.
Mouth is present at anterior tip.
Endoskeleton in these fishes is made up of hard bone while exoskeleton is made up of thin bony plates, which are known as “Cycloid” or “Ctenoid scales.”
Gills are covered over on each side by a gill cover called “Operculum.”
An air bladder is present which acts as a hydrostatic organ.
Tail fin is usually “Homocercal or Diphycercal.”
Common e.g are Eel, Sea-Horse, Flying Fish, Globe Fish etc

LUNG FISHES
Zoogeographically important fishes, belonging to group “Dipnoi, included in Class Osteiochthyes.
Only three living genera.
They respire by gills and by lungs during drought period (Lungs-Modified air bladder).
Limited distribution in South America, Africa and Australia.
E.g: Protopterus (African Lung Fish)



II) SUPER CLASS TETRAPODA
It includes following classes:
a) Class Amphibia

b) Class Reptilia

c) Class Aves

d) Class Mammalia




A) CLASS AMPHIBIA
This class includes the animals that came out of the water and established a successful life on land.
They took advantages of the improved possibilities by remaining close to water, by keeping a soft and moist skin, by developing lungs and by evolving a bony skeleton with a strong vertebral column and four legs.
They cope with seasonal changes by burrowing during extreme cold and save water by sealing themselves in a mucous envelop on dry land.
The bony endoskeleton is the main body support.
The notochord is absorbed during development
Breathing is mostly by means of skin and also lung, and also by lining of buccal cavity.
In larva the breathing is mostly by means of external or internal gills.
The circulatory system shows a three chambered heart, with two atria and one ventricle.
The amphibians are “Cold Blooded” (Poikilothermic) that is having internal temperature that very with the environment.
Eggs and sperms are laid in water and fertilization is external.
E.g: Frog and Toads, Salamanders, Newts, Mud puppies etc.



B) CLASS REPTILIA
GENERAL CHARCTERS

The earliest reptiles evolved from the amphibians.

HABIT AND HABITAT

Reptiles are generally well adapted to life on land, in semi-dry, completely dry and even desert habitat.

NATURE

All reptiles lay their eggs on land.
They are cold-blooded animals and are less active during low temperature.
STRUCTURAL FEATURES

They possess dry skin covered with epidermal scales.
In some lizards and crocodiles, small bony plates develop below the epidermal scales.
The skeleton is built on the same plane as that of amphibians, but is much stronger to support their body weight.
Respiration takes place exclusively through lungs.
Heart is three chambered, two auricles and one incompletely divided ventricle. (In Crocodiles, the ventricle is completely divided into two chambers.)
The excretion takes place through kidneys. The reptiles secrete much of their waste products in form of non-toxic “Uric-Acid.”
REPRODUCTION

In most reptiles fertilization is internal.
Eggs are provided with a shell and are laid on land.
The early development of embryo takes place on the large quantities of yolk and albumin present in the egg.
Due to the presence of a protective membrane called “AMNION” in the egg, reptiles are included in the “Amniota Group” of Vertebrates.
EXAMPLE

Alligators, Crocodile, Snake, Turtle and Gecko etc.




C) CLASS AVES (BIRDS)
EVOLUTION

Aves have evolved from reptiles.
As they acquired the capability of true flight they were able to exploit the aerial environment and became the largest class of terrestrial vertebrates.
CHARACTERS OF CLASS AVES
HABIT AND HABITAT

The birds live from pole to pole in all type of ecological zones. They all breed on land.


FLIGHT AND ADAPTATION

Feathers differentiate birds from all other vertebrates.
Feathers originated as extraordinary development of Reptilian scales.
Instead of growing all over the body and spreading evenly, the feathers grow in definite tracts.
The feathers play an important role in the thermoregulation of birds. They trap air, which is a bad conductor of heat and so prevent loss of body heat.
To fly efficiently the birds have reduced their body weight in a variety of ways.
Many bones become hollow, thin and light.
Synsacrum and pygostyle are formed by the fusion of vertebrae and give strength to skeleton.
Birds possess strong muscles to control the use of wing in flight.

ADAPTATION FOR COMMUNICATION

They possess large eyes with well-developed sight.
The birds communicate with members of their species with sound signals for which the sense of hearing is well developed.

STRUCTURAL FEATURES

The great mobility of neck is helpful in feeding, nest building, preening and defence.
There are developed a number of types of bills according to their feeding habits.
The digestive system of birds is compact and can accommodate large quantity of food.
The food is stored for a short period in the crop.
“Gizzard” possess thick muscular wall with horny lining, small stones swallowed by birds are passed on the gizzard for grinding the food.
The “Syrinx” or sound-producing organ is found in no other vertebrate except the birds. It is located at the junction between the trachea and the paired bronchi.
The lungs of birds are small, solid, spongy and slightly distensible. They are in contact with a number of air sacs.

MIGRATION IN BIRDS

A large number of species of birds exhibit a deep-rooted phenomenon of migration, during which they travel long distances from their summer breeding homes towards areas of warm climate.




SUB-CLASSES OF AVES
There are two main sub-classes of aves, which are:

i) Sub-Class Ratitae (Flightless Birds)

ii) Sub-Class Carinatae (Free-Flying Birds)


I) SUB CLASS RATITAE (FLIGHTLESS BIRDS)

This sub-class includes modern big sized flight less birds.
They comparatively have heavy weight and their wings are either vestigial or rudimentary.
They have a flat sternum without keel.
Their flight muscles are poorly developed.
The distribution of these birds is restricted to few areas of the World.
E.g: Ostrich, Rhea, Emu, Cassowary, Kiwi and Penguin.

II) SUB-CLASS CARINATAE (FREE FLYING BIRDS)

In this sub-class modern flying birds are included.
They are usually small, light weight birds with highly developed wings and feathers with interlocking system.
They possess sternum with a crest like keel to accommodate the hightly developed pectoral flight muscles.
The flying birds are distributed all around the World.
E.g: Sparrow, Pigeons, Myna, Bulbul, Hoopoes, Crow, Doves, Parrots, Fowls, Cuckoo and Ducks etc.



D) CLASS MAMMALIA
Early mammals are originated from reptiles. The distinctive characteristic of mammals are at the highest grade of development in animal kingdom.

GENERAL CHARACTERS

HABIT AND HABITAT

Mostly terrestrial, a few aquatic.


NATURE

They are warm-blooded animals.
They can maintain a fairly high body temperature and so can successfully survive in colder areas of the world.

TEMPERATURE REGULATION

Heat is generated by high metabolic rate of their body and is lost by increasing blood circulation in the skin and evaporation of sweat.
The mammalian body temperature is maintained at 35˚C-40˚C.

APPARENT FEATURE

All mammals possess hair on skin.
Sweat glands and sebaccous glands are present on skin.
Mammary glands secrete milk in females.
External ears (Pinna) are present.
Teeth are heterodont i.e. not uniform. The different types of teeth are: Incisors, Canine, Premolars, Molars.

SKELETAL SYSTEM

Skull with two occipital condyles is present.
Lower jaw is composed of single bone on each side.
Vertebrae are “Gastrocentrous,” composed of three pieces i.e. the centrum and two epiphyses.
Digits of fore and hind limbs are usually five.
Cervical (Neck) vertebrae are seven.

INTERNAL FEATURES

A thick muscular septum “Diaphram” is present between abdomen and thoracic cavity.
Heart is four-chambered.
R.B.Cs are non-nucleated.
Brain with four optic lobes.
Kidney is metanephrous.
The stomach is simple sac but rarely complicated.

REPRODUCTION

Mammals give birth to young ones (Viviparous), which are nourished by parents. Except Prototherians that lay eggs.
Fertilization is internal.
Development of eggs occurs in the uterus of female, where the developing embryo develops relationship with mother (Placenta).
After the birth of the child, the mother nourished her young ones.



CLASSIFICATION OF CLASS MAMMALIA
Mammals are divided into three sub-class:


1. SUB-CLASS PROTOTHERIA

Includes the egg laying mammals. For example Duck billed, Echidna (Spiny anteater).


2. SUB-CLASS METATHERIA

Includes the pouched mammals, also known as “Marsupial mammals.” For example Kangaroo, Koala Bear and Opossums etc.


3. SUB-CLASS EUTHERIA

Includes the placental mammals. For example Monkey, Cow, Elephant, Cat, Dog, Bat, Whale and Human being etc.






Summary of Kingdom Anamalia

(1) PHYLUM PORIFERA
Porous body
CaCO3 Silica Skeleton
Asymmetrical
Amphiblastula larva
Diffuse cellular organization
Spongocoel body cavity



(2) PHYLUM CNIDARIA
Radially symmetrical
Body cavity “Coelentron”
Pnedoblast – Defensive cells
Diploblast (Ecto + Endoderm)
Middle non-cellular layer “Mesoglea”
Larva – Planula Larva
Morphologically
a- Medusa = Umbrella like

b- Polyp = Rod shaped




(3) PHYLUM PLATYHELMINTHES
Flatworms
Totally Parasite
Flat or Ribbon shaped
Excretory organs – Proto nephridia (Flame cells)
Aeoelomate (Absence of body cavity)
It is the first phylum containing triplo blastic animals
Usually Hermaphrodites
Planaria is the only free living member
High fertility rate
Bilaterally Symmetrical



(4) PHYLUM ASCHELMINTHES (NEMATODA – ROUND WORMS)
Totally parasitic including 50 human parasite
Bilaterally symmetrical with cylindrical body
Two openings (Mouth & Anus)
Psudocoelomates
Common diseases – Ascariasis, filiariasis (elephantiasis), hook worm infection.



(5) PHYLUM ANNELIDA (SEGMENTED WORMS)
Metamers (External segmentation)
Septae (Internal segmentation)
Setae (Locomotary organs) or cheata
Digestive, excretory, nervous, reproductive system well developed.
Respiration through diffusion
Blood is red with a closed type of circulatory system (with many pulsatile hearts)

CLASS POLYCHEATA

Setae with Parapodia
Separate sexes
Sabella (Peacock worm), Nereis (Clam worm)

CLASS OLIGOCHEATA

Setae without Parapodia
Pheretima (Earth worm)

CLASS HIRUNDINIA (LEACHES)

Free living, Ecto or Endo parasite
Contains a Enzyme hirudin which prevents blood clotting



(6) PHYLUM MOLLUSCA (SOFT BODIED ANIMAL)
Second largest phylum
Largest invertebrate – Gram squlds
External hard covering calcium carbonate shell
A grinding structure radula is present in the buccal cavity
Thin membraneous covering of the body – mantle
Respiration through gills
Locomotary organ a mascular foot
Larva – Trocophore larva

CLASS GASTROPODA

A phenomenon torsion is present in which the animal body rotates at the angle of 180˚

Example: Pila


CLASS BIVALVIA

Second largest class of mollusca
Shell consist of two parts and attached with eachother by hinge joint
Common examples: Unio, mytilus and pearl oysters

CLASS CEPHALOPODA

All members are marine
Locomotary organ foot transformed into suckers which bears tentacles and arms
Example: Sepia (cuttle fish), loligo (squids), octopus (devil fish)
Shell is absent in octopus



(7) PHYLUM ARTHROPODA ( JOINTED LEGS)
Largest phylum
One million species
Metamerically segmented animals
Blood filled cavity hoemocoel is present
Blood without haemoglobin (white)
Respiration: Gills, Trachea or Book lungs
Excretory organs malphigian tubules
Nervous system well developed
Compound erges with sharp vision
Metamorphosis = developmental changes which transforms a larva into its developed adult form
Incomplete metamorphosis = egg → nymph → adult e.g. cockroach
Complete metamorphosis = ® egg ® larva ® pupa ® adult e.g. Butterfly, common, housefly and mosquito
Moulting (ecdysis)
Changing over of old exoskeleton and formation of a new one
Apiculture => Farming of honey bees
Sericulture => Farming of silk worms

CLASS MEROSTOMATA

Limulus (king crab)


CLASS ARCHINIDA (SPIDER LIKE)

Group of Spiders & Scorpions
Respiration through book lungs
Four pair of walking legs

CLASS CRUSTACEA

Class of prawns, shrimps, lobsters, crabs
Two pairs of antenae, one pair of mandible and two pair of maxilla
Exoskeleton a large plate of carapase
Sacculina is the only parasitic member

CLASS MYRIAPODA

Class of millipedes and centipedes
Body is divided into similar multiple segments

CLASS INSECTA OR HEXAPODA

Largest class (eight lakhs & 50,000 members)
Study of insects is called entomology
Three pairs of walking legs
Pterygota (insects with wings)
Apterygota (insects without wings)
Social insects: Ants, termites, honey bees



(8) PHYLUM ECHINODERMATA (ANIMAL WITH SPINY SKIN)
Marine animals
Radially symmetrical
Pentamerous body
Water vascular system is present
Locomotary organs are tube feets = External openings of the water vascular system
Exoskeleton is made up of calcarious plates in the form of spines
Power of regemeration is very great
Phylum echinodermata, hemichordata & chordate posses common ancestor
Bipinnaria larva is present
Common e.g. Sea Star (Star fish, Brittle star, Sea dollar, Sea urchins, Sea cucumbers.



(9) PHYLUM HEMICHORDATA (ANIMAL WITH HALF NOTOCHORD)
Notochord in future = Vertebral column + Skull
Dorsal nerve cord = Brain and Spinal cord
Pharengeal gill slits <-->Aquatic animals = gills
-> Terrestrial = Internal neck structures
Only 90 species are present
Larva is tornaria larva
Open circulatory system



(10) PHYLUM CHORDATA
GROUP ACRANIATA
Brain without any covering or skull


SUB-PHYLUM UROCHORDATA

Also known as tunicates
Body is enclosed in a sac tunic
Only embryonical stages show chordate characters

SUB-PHYLUM CEPHALO CHORDATA

Embryonic as well as adult both forms show typical chordate characters

GROUP CRANIATA OR VERTEBRATA
Brain and spinal cord is enclosed in a hard covering skull & vertebral column respectively


SUB-PHYLUM AGNATHA (ANIMALS WITHOUT JAWS)

Also known as cyclostomes or jawless fishes
Totally parasitic
Teeth are present in the form of rings
Common e.g. Hag fishes, lamprey

SUB–PHYLUM GNATHOSTOMATA (ANIMAL WITH JAWS)

Teeth may be present or absent
Amphibians and bird lack teeth
Fishes, reptiles, mammals do have teeth



1. SUPER - CLASS PICSES (FISHES)
Study of fish is known as echthylogy


SUB – CLASS CHONDRICHTHYES (CARTILAGENOUS FISHES)

Endo skeleton is cartilaginous (soft boned)
Exoskeleton – Placoid scales
Fins are heterocircle (different size and shaped)
Gills without any covering
Common example (Sharks, Squids, torpedo, electric ray)
Scolidoen (dog fish) – Small Shark

SUB - CLASS OSTEOCHYTHES (BONY FISHES)

Exoskeleton cycloid or ctenoid scales
Operculum is present (covering of gills)
Fins are homocircle (Same size and shape)
Lung fishes are included in order dipnoi.
2. SUPER CLASS TETRAPODA
1. CLASS AMPHIBIA
Exoskeleton is absent
Respiration by lungs, gills or skin
Fertilization is external
Cold blooded
Having the characteristics of hibernation & aestivation
Common e.g. Toads, frogs, salamanders etc.



2. CLASS REPTILIA
Included in group amniota due to the presence of amnion in eggs
Fertilization is internal
Exoskeleton is made up of thick horny scales
Important members are snakes, turtles, lizards, crocodiles and alligators
Venom → Snake poison
Fangs → sharped and curved teeth of snake



3. CLASS AVES (BIRDS)
Study of birds is called ornithology
They posses hollow bones (Pneumatic bones)
Sound producing organ “Syrinx” is present instead of larynx.
Teeth totally absent.

SUB CLASS RETITA (FLIGHT LESS BIRDS)

E.g. Penguin, Kiwi, Ostrich.
Ostrich → Largest Bird.

SUB CLASS CARNIATAE (FLYING BIRDS)

Wings with interlocking system.
Common e.g. Peacock, Seagulls, Kites, Falcon etc.
Archeopetryx → Intermediate specie between reptiles and birds.



4. CLASS MAMMALIA
Presence of mammary glands and hairs.
A muscular organ diaphragm, which separates thoracic cavity from abdominal cavity.
Teeth are present with different size and shape (heterodont).
a- Incissors → for biting and cutting purpose

b- Canives → Tearing purpose

c- Pre-Molars -> For grinding and holding purpose

d- Molars -> For grinding and holding purpose


SUB CLASS PROTOTHERA (EGG LAYING MAMMALS)

Also called monotremous.
Two genera with 3 species
Oviparous.
Common urogenital opening Cloaca is present.
External ear is absent.
It is a connecting link between reptiles and true mammals. e.g. spiny anteater, duck billed platypus.

SUB CLASS METATHERIA (POUCHED MAMMALS)

Marsupials
Give birth to live young ones.
Special pouch like bag is present in the ventral side of female.
This pouch is known as marsupial.
Common e.g. Kangaroo, Kuala bear, Opossums.

SUB CLASS EUTHERIA (PLACENTAL ANIMALS)

95% of mammals are included in this group.
Viviparous.
Placenta → connecting link between mother and fetus.
Common e.g. Camel, donkey, elephant, bat, whale, dolphin.
Markhor is the national animal of Pakistan also known as Wild goat.