Cnidarians are a phylum of principally marine invertebrates that includes inter alia coral, anemones, and jellyfish. A defining feature of a cnidarian is its nematocyst or cnidocyst , the secretory subcellular capsule responsible for delivering a cnidarian’s characteristic sting . The kinetics of nematocyst discharge can occur on the nanosecond scale, providing an acceleration upwards of 5 million g. Cnidarians generally have a radial body plan with a rudimentary nervous system. This nerve net does not exhibit cephalisation and is instead distributed.

We obtained a sample of a scyphozoan, or true jellyfish, from a local supermarket and examined its microscopic structure. The sample was derived from the organism’s tentacle, the principal site of nematocyst concentration. The sample was translucent in character; the interior of the specimen is to the bottom and left of the provided images. Although some structure is evident, it’s not apparent whether this is due to the organism’s internal organization or a consequence of the dissection and preservation process.