Diversity in Living Organism CBSE
Biodiversity
Kingdom Animalia: In this kingdom living organisms are divided into ten groups or
phyla. They are porifera, cnidaria, platyhelminthes, nematoda, annelida,
arthropoda, mullusca, echinodermata, protochordata, vertebrata.
1. Porifera: which means ‘pore-bearers’, the
sponges. Porifera is the simplest multi-cellular marine animals which have pore
all over their body. They are simple and sessile organisms, for this reason
once they are considered as plants. They have special canal system. Water with
food enters their body through pores (osties) and exit through a large opening
on the top. Porifera have skeleton which consists of calcareous or siliceous
spicules.
Example:
Marine sponges: Sycon, Spongia, Euplectella
Fresh water sponge:
Spongilla.
2. Cnideria/ coelenterata: They are sac-like animals.
Coelenterata means hollow gut. Their body has a sac-like body cavity with a
single opening to the outside for ingestion and ejection. They are mainly
marine animals except hydra. Cnidaria or coelenterata bears stinging cells
called cnidoblasts. They have hard calcareous exoskeleton.
Example:
Hydra, Jelly fish, sea anemone etc.
3. Platyhelminthes: They are ‘flatworms’. They are
mostly parasitic animals and triploblastic animals means their body is covered
with three layered cells. Their body is unsegmented without a body cavity and
leaf like or ribbon like structure. The excretory organ is flame cells present
and respiratory, circulatory or skeletal systems are absent.
Example:
Planaria, Blood fluke, Liver fluke, Tapeworm etc.
4. Aschelminthes/Nematoda: They are ‘roundworms’. They may be
parasitic or free living. They are long cylindrical and without a body cavity.
Pseudocoelom present and a complete canal system with mouth and anus present.
Respiratory, circulatory and skeletal systems are absent.
Example:
Roundworm, pinworm, filarial worm etc.
5. Annelida: They are segmented or ring worms.
They are available in fresh water, sea water or moist soil. Their bodies are
segmented and all these segments joined one after another from head to tail,
hence they are called metameric. In Annelida true body cavity present. They are
triploblastic and bilaterally symmetrical, their excretion organ is nephridia,
blood is red because of haemoglobin.
Example:
Earthworm, cattle leech etc.
6. Arthropoda: They are joined legged animals.
They have largest number of species (more than 700,000 species). They are
available everywhere on earth (land, soil, water, as parasites). In Arthropoda,
six or more legs present and they are jointed. They are triploblastic and body
is divided into head, thorax and abdomen. Body covered with chitinous
exoskeleton. They moult their old skin during process or growth. Open
circulatory system present and their breathing organ is gills or tracheae or
book lungs or body surface. Excretory organ is malpighian tubules and compound
eyes present.
Example:
Silk moth, crab, honey bee, cockroach, scorpion etc.
7. Mollusca: They are soft bodied animals. Their
body is soft which covered by hard shell made by calcium carbonate. Body is
divided into head, foot and hump. Their respiration organ is ctenidia and open
circulatory system is present. Colour of blood is blue because of haemocyanin.
Muscular foot is present for locomotion.
Example:
Snail, cuttle fish, squid etc.
8. Echinodermata: They are spiny skinned animals.
They mainly marine animals and spines or projections are present as outer
covering. They are triploblastic, radially symmetrical, simple complete
digestive system present. In Echinodermata, water vascular system is present
and has tube feet for locomotion.
Example:
Star fish, sea urchin, sea cucumber etc.
9. Protochordata: Usually they are marine animals.
They are bilaterally symmetrical, triploblastic and coelomate. The notochord,
which is rod like structure is present at some stage of life.
[Notochord
is a long rod-like structure that separates the nervous tissue from the gut and
runs along the back of the animal.]
Open blood
vascular system is present and blood is colourless.
Example:
Amphioxus, Balanoglossus, Herdmania etc.
10. Vertebrata: The chordates which possess a
backbone are called vertebrata. In vertebrata usually present most developed
animals. They have the following five features during their early stages:
A. presence of nerve cord,
B. presence
of notochord at some stage of life,
C. presence
of gill slits,
D. presence
of post-anal tail,
E. they are
triplobalstic and coelomate.
Vertebrata
divided into five classes: (i) Pisces (ii) Amphibia (iii) Reptilia (iv) Aves
(v) Mammalia.
(i) Class Pisces: All type of fishes is consisting of
this class Pisces. Usually pisces are aquatic animals and have scales. Their
body is streamlined; fins are present and have muscular tail for movement. They
breathe through gills and have two chambered heart. They are cold-blooded, lay
eggs and may be bony (carps, sea horse, flying fish) or cartilaginous (shark).
(ii) Class Amphibia: Usually they can live both on land
and in water. Amphibians are first vertebrata which live on land. Their skin is
smooth endoskeleton present. Their breathing organ may be lungs, skin, gills or
buccal lining. Three chambered heart is present and they lay eggs. Their limbs
are tetrapodus and pentadactyl type.
Example:
Frog, salamander, toad etc.
(iii)
Class Reptilia: Usually they are creeping vertebrates. They are first
completely terrestrial animals. They are cold blooded and body is divided into
head, neck and trunk. Tail may be present or absent. Two pentadactyl limbs are
present (except snake). They breathe through lungs and their body is covered by
horny scales. Incomplete four chambered heart is present and they lay eggs.
Example:
Lizard, snake etc.
(iv) Class Aves: They are ‘feathered reptiles’. All
birds included this class. They are worm blooded; their body covered by feather
and divided into head, neck, trunk and tail. Their fore limbs change into wings
and bones are hollow. Complete four chambered heart is present and they breathe
through lungs. They have strong beak and lay eggs.
Example:
Pigeon, penguin, ostrich, sparrow, duck etc.
(v) Class Mammal: Due to presence of mammary glands
they are called mammals. They are most evolved group of organisms. They are
worm blooded and have two pairs of pentadactyl limbs. They are thecodent and
breathe through lungs. Four chambered developed heart is present. They give
birth their young ones means they are viviporous.
Example:
Human beings
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