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The cubomedusae are well known as having a potent sting, particularly the Australian sea wasp Chyronex fleckeri, a large jelly (football‐sized bell and bigger) that can cause open welts in humans and, with severe stings, even respiratory distress and death. The virulence of cubomedusan venom allows the group to take large prey.

Figure 3.19 Prey capture and ingestion in Carybdea marsupialis. (a) Prey capture; (b) Prey transfer to mouth; (c) Prey ingestion.

Source: Adapted from Larson (1976).

The importance of a strong venom and nematocyst system in cubomedusae is underscored by a description of the feeding behavior of the Caribbean cubomedusa Carybdea marsupialis (Larson 1976). Carybdea has four robust tentacles that can reach 30 cm in length when extended or about 10 times the height of the bell. Prey are captured on the tentacles by annular nematocyst batteries that paralyze and trap the prey on the tentacle with considerable adhesive force. The “sticking power” of the nematocysts is so strong that fish too large for Carybdea to handle must break the tentacle to escape. Once the prey is subdued, it is conveyed into the bell cavity and onward to the digestive system by an inward flexion of the tentacle (Figure 3.19). The outer digestive region, or manubrium, is short, and its outer lips are prehensile, so that when a prey item is contacted, it is quickly engulfed.

Though data are limited on the diets of cubomedusae, the little data available suggest a varied menu including polychaetes and small fish as well as the more typical small crustaceans (Table 3.4). Observations reported in Larson (1976) suggested some selectivity for fish by Carybdea marsupialis.