Coelenterazine is found in radiolarians, ctenophores, cnidarians, squid, brittle stars, copepods, chaetognaths, fish, and shrimp. Hemispadella is a genus of chaetognaths in the family Spadellidae. Calispadella is a genus of chaetognaths in the family Spadellidae. Xenokrohnia is a genus of chaetognaths in the family Heterokrohniidae. Archeterokrohnia is a genus of chaetognaths in the family Heterokrohniidae. Bathyspadella is a genus of chaetognaths in the family Spadellidae. At first, it was anabaritids and "Protohertzina" (the fossilized grasping spines of chaetognaths) fossils. The larva is consumed by siphonophores and chaetognaths. Heterokrohnia is a genus of chaetognaths in the family Heterokrohniidae. Krohnittidae is a family of chaetognaths in the order Aphragmophora. However, based on molecular data, micrognathozoans may be more closely related to rotifers than chaetognaths. Other zooplankton include cnidarians, ctenophores, chaetognaths, molluscs, arthropods, urochordates, and annelids such as polychaetes. All chaetognaths are carnivorous, preying on other planktonic animals. These may include fish, chaetognaths, krill, copepods, radiolarians, phytoplankton, nematocysts, ostracods and detritus. Chaetognaths are traditionally classed as deuterostomes by embryologists.