Question

1. Give some examples of colonial animals where the individual units within a colony are specialized for different functions. What are the functions? What colonial animals do not show specialization within a colony, i.e., all the units are instead functionally equivalent. Be sure to consider this question at the level of phyla and do discuss ALL of the colonial phyla that we have discussed in this course. Note if all the members of the phylum share the features you mention or only a subset.

Answer 1

Honey bees is an example of colonial animals where the individual members within a colony are specialized for different functions. Bee is a social, polymorphic and colonial insect. It has three main castes- queen, drones and workers. Queen is the only fertile female of the colony which continues to lay eggs for 2-5 years. Drones are male honey bee. They develop from unfertilized eggs. Drones and virgin queens take part in nuptial flight. After copulation the drones are not allowed to come back into hive. Workers are sterile females. There is a class of workers known as scout bees search for food and intimate the same to worker bees by dances-round dance for less than 75m and tail wagging dance for longer distances. Workers have a pollen collecting apparatus, honey storing mechanism and wax secreting glands. Young workers secrete royal jelly which is given to queen or potential queens.

Another example of animals showing colonial specialization is Siphonophorae, an order of Hydrozoans which is composed of medusoid and polypoid zooids. These structures are morphologically and functionally specialized. Zooids are the multicellular units that form the colonies from a solitary bud called pro-bud by asexual means. Each pro-bud produces diverse zooids with functional specialization and are genetically identical. The zooids are morphologically distinct as they possess different body plans exhibiting between the polyp and medusae.

Corals forms colonies in order to survive i.e they are obligatory bounded to form and live as colony. But all the individual units in a coral colonies are functionally equivalent. This means that they do not show specialization. Corals are animals that are physically connected by living tissue that contains a shared gastrovascular cavity. This gastrovascular cavity is divided into compartments by complete or incomplete mesenteries or septa, so each units function independently and equally in all aspects.