Why are there no insects in the sea?

2 figuresBefore I start this post, I would like to make it clear that I am not an entomologist, so I apologize if I say anything very wrong; I hope not. Although I am sure many of you, indeed connoisseurs of the subject, are already thinking, “there are insects in the sea”. Certainly, several species of Halobates live on the surface of the ocean, and some other insects in interstitial areas of beaches, but they are quite rare and do not go into the sea depths. The fact I want to point out here is that compared to the richness and abundance of insects on land it is surprising that there are virtually none in the sea. The reasons can be diverse, and theories are not lacking: To start with, the insect’s respiratory system is aerial and does not allow the exchange of gases in the water. This, however, has been solved by some beetles, or larval stages of dragonflies and mosquitoes, to name a few examples, which live in lakes and rivers. Then, what happens at sea? It has been speculated that insects, being aerial, would not have the ability to migrate to deep areas of the ocean during the day to avoid predation, as do groups of similar size to the se