Coelom and Blood System

• Coelom: internal fluid-filled cavity that develops in the mesoderm of triploblastic animals
• The coelom separates the digestive tract from the body wall
• Diploblastic animals do not have a coelom
• Acoelomate


  has no cavity (coelom) in the mesoderm
• Pseudocoelomate


  has a coelom, but not seen as a 'true' coelom because it is not only surrounded by a mesoderm tissue
• Coelomate

  has a true coelom, a cavity in the mesoderm
• Acoelomate, Pseudocoelomate, Coelomate

  
• The coelom separates the digestive tract from the body wall- ensuring that each functions independently of the other
• A fluid filled coelom can act as a hydrostatic skeleton
• The presense of a coelom allows animals to reach a considerable size and become more complex by providing space for organs to develop
• Coelomic fluid serves as a transport medium for substances such as gases, nutrients and wastes
• Due to the separation of the digestive tract from the body wall by mesodermal organs in triploblastic animals, there was a need for a transport system
• A blood system was developed in most triploblastic animals for the transport of O2, CO2 and digested nutrients as well as an excretory system to transport waste products