CORALS AND BRYOZOANS
In spite of common points in their organization, corals and bryozoans have no family tie in the classification of the living beings.
Common points :
These two kinds of aquatic plant-like animals live more often that not in colonies of little boxes that they secrete within a calcareous skeleton. Every individual of a colony (zooid for bryozoans or polyp for corals) possesses a coronet of tentacles in the middle of which the mouth is situated. Food is constituted by plankton.
Differences :
Every cavity (or zooecia) containing an individual of a bryozoans' colony presents a section with a tiny size, but the colony can itself reach several tens of centimeters for some species.
bryozoans' colony
In corals, every individual has a millimetric to centimetric size and lives in one of the starry calyxes which characterize these animals. Corals form mostly colonies but some are lonely.
isolated coral
corals' colony
Corals are exclusively marine and almost all live in shallow and warm water (between 21 and 30°C), where they can constitute reefs. Bryozoans are more distributed geographically. Many current species occupy the coral reefs but some live in the temperate seas or even in fresh water. We can also meet some of them in very big depth.
Most of the corals live in symbiosis with tiny seaweeds which supply them, by the photosynthesis, with an important part of food. In return, seaweeds feed partially on products of the coral's metabolism. In bryozoans, we know symbioses with bacteria at the time of the fastening of the bryozoans' larvas on their future support. Into the faluns, we find frequently skeletons resulting from a symbiosis between bryozoans Celleporaria palmata and corals Culicia parasitica or Cryptangia woodi.
symbiosis between corals and bryozoans