Evaluate Basic External Animal Anatomy and Morphology - AgriSETA

Evaluate Basic External Animal Anatomy and MorphologyPrimary Agriculture NQF Level 1 Unit Standard No: 11617329Session 2Anatomy and Morphology ofInvertebrate AnimalsAfter completing this session, you should be able to:SO 2: Identify and name the components and the externally visibledivisions or parts of an animal and identify gross abnormalitiestherein.In this session we explore the following concepts:In the previous session the vertebrates were discussed.Although they show marked differences in external structure they still haveimportant characteristics in common.All the vertebrates have a vertebral column (spinal column) and anendoskeleton (skeleton inside the body). Not all animals are vertebrates.The other major group are the invertebrates. Two groups of invertebrateanimals will be studied: the insects and the crustaceans that fall under thephylum (division) Arthropoda (a phylum of the animal kingdom comprisedof organisms having a hard, jointed exoskeleton and paired joints and legs).The other group will be the Phylum Mollusca, or ‘soft-bodied’ animals.2.1 AnthropodaUnlike the vertebrates, the arthropods all have an external skeleton or exoskeleton(hard structure on the outside of the body). There are various kinds of exoskeleton,but all are made primarily of a non-elastic, waterproof substance called chitin. Theexoskeleton can be very limiting, particularly with regard to movement.Animals with exoskeletons never grow to any great size. It is known that threequarters of all known animals are Arthropods. Because they can adapt to a largevariety of environments they are widely distributed in the world.Version: 01 Version Date: July 2006