This simplest of all the cnidaria has, it is true, a crown of tentacles round its mouth.

There are four stems belonging to the coelenteria: the gastraeads ("primitive-gut animals"), sponges, cnidaria, and platodes.

In most of the cnidaria and many of the annelids (worm-like animals) they remain unchanged throughout life.

This we find in the lower cnidaria and worms, as well as in the more highly-developed molluscs, echinoderms, articulates, and vertebrates.

The lowest form of the Cnidaria is also not far removed from the gastraeads.

Their phylogeny has remained problematic, with studies placing them within either the Bilateria or Cnidaria.

Cnidaria This lion's mane is the largest known jellyfish and belongs to the Cnidaria phylum.

The lowest Cnidaria (the hydroid polyps) also are little superior to the Gastraeads in structure.

Radiata, that include the phylum Cnidaria, have a blind-sac form of digestive tract with only one opening.

These special excretory organs are not found in the other Coelenteria (Gastraeads, Sponges, Cnidaria) or the Cryptocoela.

"Some noxious spray emitted by the malefic cnidaria as it murdered poor Marissa?"

Until now, there is a lack of knowledge about the presence of chitin in numerous representatives of corals (Cnidaria).

As I began to write this summary chapter, I therefore aimlessly searched through images of Cnidaria from my collection of antiquarian books in paleontology.

Among the latter we might list Gnathostomulida (marine worms), Cnidaria (jellyfish, medusae, anemones, and corals), and the delicate Priapulida (or little "penis worms").