Feeding Apparatus of Bryozoa

Kingdom: Animalia,

Class: Lophophorata,

Phylum: Bryozoa

Bryozoa(Polyzoa/ Ectoprocta/ moss animals) are filter feeders that sieve food particles out of the water using a retractable lophophore, a "crown" of tentacles lined with cilia. Bryozoan colonies are called zooids.

Bryozoans have two types of feeding apparatus.Those apparatus plays a very important role in feeding mechanism of bryozoa.

1. External
2. Internal

1. External:-
   
   1. Lophophore:- The Lophophore is a circular fold of body wall that encircles the mouth and consists of a basal ridge continuous with a row of ciliated tentacles.
   2. Tentacles with cilia:-
      
      1. The numbers of tentacles varies in different species from 8 to 34.
      2. The tentacles are hollow, containing a coelomic lumen continuous with a ring coelom in the lophophora base.
      3. Each tentacle is roughly rectangular or triangular in section.
      4. The outer surface and tentacular tips are devoid of cilia and provided with the projecting tactile hairs of neurosecretory cells.
      5. The cilia occurs as a pair of longitudinal tracts.
      6. The median cilia lack the power of motility according to some authors.
      7. The tentacles are independently movable by way of longitudinal muscles fibres, situated along the inner and outerside, just beneath the peritoneum.
      8. Shorter frontal cilia are present within the inner side of tentacles.
2. Internal:-
   Alimentary system:-
   1. The digestive tract(‘U’ shaped) starts from the mouth and ends to anus, which are placed outside the circle of tentacle.
   2. The mouth is a simple round opening encircled by the lophophora base.
   3. The mouth is closable with circular fibres and may also be provided with radial fibres.
   4. The mouth leads into a wide chamber.