Question

What are Zooids in Cnidaria?

Answer 1

Hint: More complex than sponges and approximately as complicated as Ctenophores (comb jellies), Cnidarians are a group of creatures that includes virtually all other species in the world.

Complete answer:
Hydroid colonies contain zooids, which are individual polyps. For example, gonozooids are responsible for reproduction, whereas gastrozooids are responsible for eating.
Zooids are multicellular and have a comparable structure to other solitary creatures. As with corals, Catenulida, Siphonophorae and Pyrosomes, zooids can be directly linked by tissue or share a shared exoskeleton (e.g. Bryozoa or Pterobranchia).
Telescoping is sometimes caused by a polyp or a tumour in the intestines in adults (called a lead point). They grip this lead point and drag it and the intestinal wall into the colon ahead of them.
Polymorphism may be found in zooids. Extant bryozoans, for example, may have zooids suited for various purposes like feeding, colony anchoring, and embryo brooding. However, fossil bryozoans are only known through the colony formations that the zooids constructed during their lives.
Temperature and the size of certain zooids have been shown to be correlated. Differences in zooid size within ancient colonies can be used to predict the temperature and periodicity of oceans in the geological past.
Originally, the term zooid has also been used to refer to an organic cell or structured entity that moves independently inside a live creature, particularly a motile gamete.

Note:
As part of the Animalia kingdom, Cnidaria has more than 11,000 species of aquatic creatures, most of which are found in marine settings. Specialized cells known as Cnidocytes provide them an edge over other predators.