Welcome to Phylum Cnidaria! Here we start getting into the slightly more complex animals, just barely beating out the sponges. A defining characteristic in this phylum is their stinging cells: the cnidocytes. You can watch this cool video about cnidocytes (and how the stinging organelle, nematocysts, work) by checking out this 6 minute video by some researchers in Australia:
This group contains various classes of stinging animals such as:
- Class Scyphozoa - Marine jellyfish ()
- Class Anthozoa - Sea anemones and coral ()
- Class Cubozoa - Box Jellyfish (video ...)
- Class Hydrozoa - Everything else that stings (video ...)
As always, phylogeny changes constantly as we learn new techniques to better explain the evolutionary relationships between organisms. These videos follow along with the free, online textbook OpenStax Biology 2e (https://opensta