Chapter 10

  1. Discuss two ways in which bryozoans may reproduce asexually

   

  1. Zooloids undergo budding to produce daughter zooloids from a single larva that develops into one or more mature zooloids which undergo budding as well and so on and the colony is formed
  2. Forming statoblasts that can resist extremes in temperature and moisture which can be produced in adverse environmental conditions. The statoblasts are released when the parent colony disintegrates (when favorable conditions) return and they transform into new zooloids and recolonize the area
    1. Discuss the advantages a coelom (body cavity) affords an animal

   

  1. Provides space for development of internal organs
  2. Organs within the coelom can independently of the outer body wall
  3. Gonads have room to grow into the zoelomic space during breeding seasons to increase reproductive potential
  4. Coelomic fluid often acts as a simple circulatory medium, helping transport nutrients, gases, and wastes
  5. Cells can be bathed by coelomic fluid and can receive nutrients and oxygen while excreting wastes into the coelomic fluid
  6. It can also act as a hydrostatic skeleton which improved locomotion
    1. What are the advantages of a digestive tract having a separate entrance at

   

  1. Permits food to pass through the body in one direction and opens up the possibility for different regions of the digestive tract to become specialized for different roles – increasing digestive efficiency
    1. Match the organism with the correct description

   

  1. Rotifers (phylum Rotifera)

       1. Free-living, freshwater organisms with a corona and mastax

  1. Acanthocephalans (phylum Rotifera)

       1. Wormlike, intestinal parasites with spiny proboscis

  1. Moss animals (phylum Bryozoa)

       1. Free-living, colonial organisms with tentacle crown

  1. Lamp shells (phylum Brachiopoda)

       1. Marine organisms with bivalve shell and lophophore

  1. How does the digestive system of brachiopods compare to that exhibited by bryozoans?

   

  1. Brachiopods and Bryozoans both possess a lophophore (a ring of tentacles surrounding the mouth); however, in the bryozoan the lophophore is divided into two tentacle bearing extensions that may be arranged in a circle, a horseshoe shaped, or a highly coiled arrangement. Brachiopods lophophore also does not extend forward; it remains contained within the protection of the two valves.
    1. List several specializations that bryozoans and brachiopods have evolved that represent adaptations to their sessile lifestyles

   

  1. Bryzoans lack a structural circulatory system, respiratory system, or excretory system. They also do not demonstrate cephalization and their nervous system consists only of a single ganglion and tactile receptors on the tentacle crown.
  2. Sensory neurons in the mangle edges of brachiopods serve as tactile receptors to inform the brachiopod of foreign objects that touch or disturb the animal, allowing it to close its shell for protection
    1. List several specializations that spiny-headed worms have evolved that represent adaptations to their parasitic lifestyle

   

  1. Sensory organs are absent
  2. Digestive system completely lost
  3. Most other organ systems have been reduced i. With exception of reproductive system
  4. Exchange of nutrients, gases, and waste products with the environment occurs by diffusion across the body wall
  5. Internal transport of these substances occurs by diffusion within the body cavity