Kingdom Animalia

• 4 main morphological and developmental features of animal body plans


  1.Absence or presence of true tissues 2.Type of symmetry 3.Presence or absence of a body cavity 4.Patterns of embryological development
• •PARAZOA - Phylum Porifera (‘sponges’) represent an early branch of the animal kingdom.
• •Parazoa - no true tissues
• •Eumetazoa - true tissues: stable associations of cells with a similar structure and function
• Eumetazoans - the embryo becomes layered during gastrulation and these germ layers (ectoderm and endoderm) form the various tissues and organs of the body
• Ectoderm gives rise to the outer covering
• Endoderm forms lining of the digestive tube (archenteron) and gives rise to digestive tract/cavity and organs
• •Radiata: Includes Phylum Cnidaria (hydras, jellies, sea anemones and their relatives) and Phylum Ctenophora (comb jellies) have radial symmetry
• •Bilateria: have bilateral symmetry with a dorsal and ventral side, an anterior and posterior end, and a left and right side.
• Radial Symmetry


  •e.g. sea anemone •radiates from centre. •Any longitudinal slice through the central oral-aboral axis would divide the animal into two identical halves
• Bilateral Symmetry


  •e.g. lobster •has a left and right side. •Only one imaginary cut would divide animal into two identical halves
• A bilaterally symmetrical animal has only one plane of symmetry
• Radiata


  •Diploblastic (2 germ layers: ectoderm and endoderm)
• Bilateria


  •Triploblastic (3 germ layers: ectoderm, endoderm and mesoderm)
• Ectoderm: covering the surface of the embryo, gives rise to the outer covering and, in some phyla, the central nervous system.
• Endoderm: innermost layer, lines developing digestive tube, or archenteron, and forms lining of the digestive tract and organs derived from it, such as the liver and lungs of vertebrates.
• Mesoderm develops into the muscles and most other organs between the digestive tube and the outer covering of the animal.
• •Bilateria triploblastic animals can be divided on the basis of the absence or presence and structure of a body cavity  so called coelom – a fluid or air-filled space separating the digestive tract from the outer body wall
• Absence or presence of true tissues

  -Parazoa

  -Eumetazoa
• Type of body symmetry

  Radiata

  Bilateria
• Absence or presence of a body cavity

  -Acoelomate

  -Pseudocoelomate

  -Coelomate/ Eucoelomate
• Acoelomate animals

  (e.g. Phylum Platyhelminthes: flatworms) have

  a solid body and lack a coelom
• Pseudocoelomate

  A coelom which is not completely lined with mesoderm.  Derived from mesoderm and endoderm.
• Pseudocoelomate

  E.g. Phylum Rotifera (rotifers),

  Nematoda (roundworms)
• Coelomate

  an animal with a true coelom (body cavity completely lined by mesoderm) derived only from mesoderm
• Patterns of embryological development

  These modes of development are distinguished by the form of:

  1.  Cleavage pattern

  2.  Coelom formation

  3.  Fate of the blastopore
• Lophotrochozoa: (Lopho + trocho + zoa)

  Some members have a lophophore: crown of ciliated tentacles/feeding.

  Some have a trochophore larval stage
• •3 major clades of bilaterians:

  1. Deuterostomia
  2. 2. Lophotrochozoa
  3. 3. Ecdysozoa
• Many animals can be categorized on the basis of embryogenesi
• •Protostomia development

  e.g. molluscs, annelids, arthropods and others
• •Deuterostomia development

  e.g. echinoderms, chordates