Body symmetry is the similarity of body parts in different region and directions of the body plan.
In radial symmetry, body of an individual can be divided into equal halves by any plans passing through the longitudinal axis. (e.g., Coelentrates, Ctenophores, Echinoderms.
In bilateral symmetry, body can be divided into two equal halves when the plane passes through the median longitudnal or saggital axis. (e.g., Annelids, Arthropods)
(a) Two chambered heart is present in organisms like fishes. Only one atria and one ventricle is present which are not separated and hence mixing of oxygenated and deoxygenated blood blood occurs.
(b) Three chambered heart develops after the division of auricle into right and left halves as in amphibian. Mixing of oxygenated and deoxygenated blood occurs in ventricles.
(c) An intermidiary heart is present in reptiles in which ventricle get partially divided through a septum which is incomplete. e.g., Crocodiles, thus having four-chambered heart.
(d) In four chambered heart both the auricle and ventricle are divided into two halves and thus no mixing of oxgyenated and deoxygenated blood occurs. e.g., birds and mammals.
Fill up the blank spaces appropriately
| Phylum/Class | Excretory Organ | Circulatory Organ | Respiratory Organ |
|---|---|---|---|
| Arthropoda | Lungs/Gills/Tracheal System | ||
| Nephridia | Closed | Skin/Parapodia | |
| Metanephridia | Open | ||
| Amphibia | Closed | Lung |
Excretion involves the elimination of metabolic waste products from the animal body.
Different organs are involved in the process of excretion in different animals.
(a) In Arthropods, the Malpighian tubules remove excretory products from haemolymph.
(b) In Annelids, the excretory organ occurs as segmentally arranged coiled tubules called nephridia
(c) In Molluscas, excretion occurs by paired structures called organ of Bojanus also called metanephridia.
(d) In Amphibians mesonephric kidneys are associated with excretion.
Blood circulation involves the circulation of blood and lymph along with oxygen, carbondioxide, hormones, blood cells, etc, within the body system for the nourishment of cells, fighting diseases, and for stabilising body temperature and pH .
| Open Circulation | Closed Circulation |
|---|---|
| In this, blood is pumped out of the heart into sinuses which directly open into cells and tissues, e.g., phylum-Arthropoda, and Mollusca. | In this system, blood is circulated through a series of complexly arranged vessels and capillaries e.g., phylum-Annelida and Class-Amphibia. |
Respiratory organs are involved in the exchange of gases from the atmosphere. Different respiratory organs are as follows
(a) Lungs/gills/tracheal system in arthropoda and molluscs.
(b) Skin in annelids.
(c) Lungs and skin in amphibians.
Match the following
| A. | Amphibia | (i) | Air bladder |
|---|---|---|---|
| B. | Mammals | (ii) | Cartilaginous notochord |
| C. | Chondrichthyes | (iii) | Mammary glands |
| D. | Osteichthyes | (iv) | Pneumatic bones |
| E. | Cyclostomata | (v) | Dual habitat |
| F. | Aves | (vi) | Sucking and circular mouth with out jaws. |
A. $\rightarrow$ (v) B. $\rightarrow$ (iii) C. $\rightarrow$ (ii) D. $\rightarrow$ (i) E. $\rightarrow$ (vi) F. $\rightarrow$ (iv)
A. Amphibians possess dual habitat, i.e., they are found in both aquatic and terrestrial habitat. Their larva is completely aquatic and adult lives in terrestrial as well as in aquatic habitat
B. Mammals have mammary glands which produce milk and feed their young ones. The mammary glands are enlarged exocrine modified sweat glands functional in female mammals.
C. Chondrichthyes have the cartilaginous rod (notochord) in the young stage which is gradually replaced by cartilage.
D. Osteichthyes have air bladder which is a vesicle or sac containing air,
E. Cyclostomes possess sucking and circular mouth without jaws which is surrounded by tentacles and the tongue bears teeth. e.g., lamprey and nagfish.
F. Aves have light weighted bones with internal spaces filled with air called pneumatic bones and aerodynamic lungs with specialised air sacs. These are the adaptations which enable birds to fly.
The endoparasites such as Taenia solium and Fasciola hepatica (liver fluke), etc., are found inside the host body, and survive due to the presence of certain characters.
Special characters present in by endoparasites are as folows
(i) The possess anaerobic respiration and the gaseous exchange is through general body surface.
(ii) These organisms bear additional organ for the attachment to the host. Fasciola hepatica possesses acetabulum or posterior sucker for the attachment. Taenia solium posses hooks and suckers for the attachment with the host.
(iii) Reproductive organs are well developed. They are generally, hermaphrodite and self fertilisation is common in them.
(iv) The thick tegument (body covering) is present which is resistant to the host's digestive enzymes and antitoxins.
(v) Absence of locomotary organs.
(vi) Tapeworms lack digestive organs because digested and semidigested food of the host is directly absorbed through their because body surface.