cephalization

Differences between Acraniata and Craniata

by

  S.N Acraniata Craniata 1. They are exclusively marine. They are aquatic or terrestrial. 2. They are small sized chordates. They are mostly large sized vertebrates. 3. Appendages, cephalization and exoskeleton are absent.  Appendages are two pairs usually, well developed head and exoskeleton present. 4. Coelom is enterocoelic, budding off from embryonic archenteron. Coelom is … Read more

Symmetry in animals

by

Introduction Symmetry means the arrangement of body parts into geometrical designs. Many adult sponges that are irregular in shape are said to be asymmetrical. However, the sponges start their life from a radially symmetrical larva. Four types of symmetry are found in animals. They are: spherical symmetry, radial symmetry, bi-radial symmetry and bilateral symmetry. Spherical … Read more