1. Invertrabrates
1.1. Annelida
1.1.1. Classifcation
1.1.1.1. Fertilization can be internal or external.
1.1.1.2. Sexes may be separate or united, wherein they are called hermaphrodites.
1.1.1.3. they have a long and segmented body.
1.1.1.4. These invertebrates have a true closed circulatory system.
1.1.1.5. Annelids are bilaterally symmetrical.
1.1.1.6. They are triploblastic.
1.1.1.7. Also, they exhibit organ system grade of organisation, showing organ differentiation.
1.1.1.8. The body is covered with a thin cuticle.
1.1.1.9. They are coelomate. A body cavity or coelom is present.
1.1.1.10. Annelids live in moist environments, moist soil, freshwater and marine water.
1.1.1.11. They have parapodia and chitinous setae, used for locomotion.
1.1.1.12. Their body appears red due to the presence of haemoglobin.
1.1.1.13. Excretory and nervous systems are present.
1.1.1.14. The digestive system is complete and developed.
1.1.1.15. Respiration happens through the general body surface.
1.2. Molluscula
1.2.1. All molluscs have a specialized foot used in digging, holding or moving
1.2.2. Molluscs have a mantle or mass of soft flesh that covers the soft body and encloses the internal organs.
1.2.3. Many molluscs have a radula, which, in most species, is a rasp-like scraping organ used in feeding