Question

Animals have an endoskeleton of calcareous ossicles belong to which Phylum ?

• A. Phylum Annelida
• B. Phylum Arthropoda
• C. Phylum Echinodermata
• D. Phylum Mollusca

Answer 1

Answer:

C. Phylum Echinodermata

Phylum Echinodermata:

• These animals have an endoskeleton of calcareous ossicles and hence, the name Echinodermata (Spiny bodied)
• All are marine with organ-system level of organisation.
• The adult echinoderms are radially symmetrical but larvae are bilaterally symmetrical.
• They are triploblastic and coelomate animals. 
• Digestive system is complete with mouth on the lower (ventral) side and anus on the upper (dorsal) side. 
• The most distinctive feature of echinoderms is the presence of water vascular system.

The functions of water vascular system:

1. It helps in locomotion
2. It helps to capture and transport of food
3. It helps in respiration

• An excretory system is absent
• Sexes are separate
• Reproduction is sexual
• Fertilisation is usually external
• Development is indirect with free-swimming larva.

Examples:

• Asterias (Star fish)
• Echinus (Sea urchin)
• Antedon (Sea lily)
• Cucumaria (Sea cucumber)