Stratozoa

Stratozoans are probably the most diverse and successful phylum of Polizoa. They are colonial organisms like all polizoans and are characterized by their curious method of growth. Colony development begins with a small zooid with a mouth and gastrovascular cavity, capable of capturing and digesting food. At a certain point in its life, the zooid begins to develop a small bud within its gastric cavity. This bud will grow to become a zooid with its own mouth and gastric cavity which will appear from the mouth of the parent zooid, which loses its digestive function and becomes a covering. The new zooid assumes the digestive role. This process is repeated several times until the polizoan reaches maturity.

The genus in the image is called Stratozoon, 6 cm long. In it, it can be perfectly appreciated how zooids have this stratified growth, which also branches out to form appendages with locomotor or sensory functions. The zooids located at the tips of these appendixes have been keratinized to serve as claws. The rugose zooid is the oldest in the colony and can cover all other zooids in case of danger.