Mesoderm gives rise to skeletal and muscle tissues, blood, lymph and connective tissues. Ectoderm gives rise to epidermis, hair, mammary glands and CNS. Endoderm gives rise to organs like stomach, pancreas, urinary bladder and intestines.

Annelids have ganglia in each segment that help in muscular movements. They have two ventral nerve chords throughout body. Specialized sensory receptors are present to help in sense of touch and light. Pigmented photo receptors called Oceli are present in Annelids.

Transport or canal system in Porifera helps in exchange of gases, distribution of food, water removal, garing of food. Canal system can?t help in formation of new individual. Porifera undergoes eir fragmentation or sexual reproduction to form a new individual.

Obelia (polyp) produces medusa by budding. Medusae undergoes sexual reproduction to produce polyp. Obelia exists in both forms in alternate generations. This process is called metagenesis.

Arthropods consist of three parts, namely, head, thorax and abdomen. Their respiratory organs can be eir lungs or gills. Their digestive system is complete with mouth, esophagus, intestines and rectum. Their circulatory system is of open type i.e. y don?t have eir heart or blood vessels to supply blood to organs of body.

Notochord is a rod-like structure formed on dorsal side of animals. During embryonic development, notochord gets developed from mesodermal cells. Animals are classified as chordates and non-chordates based on presence or absence of notochord. Pisces are an example for chordates.

Hemichordates have three main body parts. They are Proboscis, Collar and Trunk. Proboscis helps in excretion. Collar has a mouth and helps in peristalsis of food. Trunk has gills and helps in respiration.

Water driven tube feet system helps in locomotion as well as in excretion. Water vascular system has a ring canal which fills initially followed by that of radial canals. Echinoderms excrete waste by diffusion through tube feet. Exchange of gases takes place due to water vascular system.

In an open circulatory system, interstitial fluids and blood has no specific distinction and refore called as hemolymph. Whereas in closed circulatory system, interstitial fluids and blood has specific distinction. Because in closed circulatory system, blood flows through blood vessels.

Scales are absent and skin is dry except at one end re is an oil gland. Endoskeleton is made of bones and y respire through lungs. They are warm-blooded animals. They are dioecious and oviparous.