In , Clarke identified elephantoid legs in Cochin. The microfilariae in the peripheral blood was first identified by Lewis in in Calcutta (Kolkata). . .
Phylum: Arthropoda (G . arthros - jointed; podes- feet) This is the largest phylum of the Kingdom Animalia and includes the largest class called insecta (total species ranges from - million). They are bilaterally symmetrical, segmented, triploblastic and schizocoelomate animals with organ system grade of body organisation. They have jointed appendages which are used for locomotion, feeding and are sensory in function.
Body is covered by chitinous exoskeleton for protection and to prevent water loss, It is shed off periodically by a process called moulting or ecdysis . The body consists of a head, thorax, and abdomen with a body Figure . Examples of Annelida Earthworm Nereis Leech XI Std Biology-Zoology Chapter- . .
Phylum: Mollusca (L. molluscs –soft bodied) This is the second largest animal phylum. Molluscs are terrestrial and aquatic (marine or fresh water) and exhibit organ system level of body organisation. They are bilaterally symmetrical (except univalves eg.
apple snail) triploblastic and coelomate animals. Body is covered by a calcareous shell and is unsegmented with a distinct head, muscular foot and a visceral hump or visceral mass. A soft layer of skin forms a mantle over the visceral hump. The space between the visceral mass and mantle (pallium) is called the mantle cavity in which a number of feather like gills ( ctenidia) are present, which are respiratory in function.
The digestive system is complete and mouth contains a rasping organ called radula with transverse rows of chitinous teeth for feeding (radula is absent in bivalves). The sense organs are tentacles, eyes and osphraidium (to test the purity of water and present in bivalves and gastropods). Excretory organs are nephridia. Open type of circulatory system is seen except for cephalopods such as squids, cuttle fishes and octopus.
Blood contains haemocyanin , a copper containing cavity called haemocoel . Respiratory organs are gills, book gills, book lungs and trachea. Circulatory system is of open type. Sensory organs like antennae,