Introduction to Invertebrates Phyla: The invertebrates include those which are without backbone as opposed to vertebrates in which a series of vertebrae constitute a backbone, but this division of the animal kingdom into invertebrates and vertebrates is largely a matter of convenience. The invertebrates constitute about 90 per cent of the known animals which number over a million. Vast and [...]
The following points highlight the twenty-one general characteristics of invertebrates. Some of the characteristics are: 1. Habitat 2. Numerical Strength 3. Shape 4. Size 5. Symmetry 6. Grades of Organization 7. The Presence or Absence of Germ Layers 8. Simple Integument 9. Multiple Movement Device 10. The Presence or Absence of Segmentation and Others. Characteristic # 1. Habitat: All the [...]
The below mentioned article provides study notes on Protozoa. The name Protozoa (Gr., protos = first; zoon = animal) comes from Goldfuss (1818) who, however, used the name simply for the lower groups of zoophyta including protozoans, sponges, coelenterates, rotifers and bryozoans, It was von Siebold (1845) who, recognising the unicellular nature of the Protozoa, first used and defined the [...]