Bioniac

Phylum – Arthropoda • This is the largest phylum of Animalia which includes insects .  • Over two-thirds of all named species on earth are arthropods  •They have organ-system level of organisation. •They are bilaterally symmetrical , triploblastic , segmented and coelomate animals.  • The body of arthropods is covered by chitinous exoskeleton .  • The body consists of head, thorax and abdomen .  •They have jointed appendages ( arthros-joint , poda-appendages ). • Respiratory organs are gills , book gills , book lungs or tracheal system . • Circulatory system is of open type. • Sensory organs like antennae , eyes ( compound and simple ), statocysts or balancing organs are present. • Excretion takes place through malpighian tubules . • They are mostly dioecious .  • Fertilisation is usually internal . • They are mostly oviparous . • Development may be direct or indirect . Examples:  • Economically important insects – Apis (Honey bee), Bomby...