No, dolphins are not communicating with extraterrestrials that we know of. This Aeon article is pretty interesting stuff though about how the study of dolphin intelligence and the search for extraterrestrial intelligence have been intertwined over time though. The consensus these days seems to be that dolphins are as about as smart as a human toddler, which is pretty smart if you think about it, but not smart enough to build a technological civilization. This article contains some musings about whether technological civilizations are the inevitable end state of the evolution of intelligent life, whether another one would arise on Earth if ours disappeared for some reason (but life itself did not), whether there are likely to be others out there, whether they are likely to have come and gone, and if so why.
Later, at the first Soviet-American conference on communication with extraterrestrial intelligence (CETI) in 1971, it was suggested by some attendees that we don’t see evidence of supercivilisations across the galaxy because the only ones that persist are the ones that give up the risky path of technology and instead pursue immersion in nature. Ageing civilisations either self-destruct or shift focus to something like Zen Buddhism, it was conjectured: pursuing spiritual and qualitative self-perfection at the cost of all interest in external reality or ‘“quantitative” expansion’. The Russian astrophysicist Vladimir M Lipunov speculated that, across the Universe, the scientific mindset recurrently evolves, discovers all there is to know and, having exhausted its compelling curiosity, proceeds to wither away. By 1978, the philosophers Arkadiy Ursul and Yuri Shkolenko wrote of such conjectures – concerning the ‘possible rejection in the future of the “technological way” of development’ – and reflected that this would be tantamount to humanity’s ‘transformation into something like dolphins’.
Aeon
It’s a bit of a puzzle why we haven’t discovered any signals out there despite looking for around half a century. I recently listed to this Science Vs. podcast where someone likened our search so far to dipping a cup in the ocean and not coming up with any fish. You wouldn’t conclude from that that fish do not exist, just that they do not exist where you dipped the cup. The expert interviewed went on to say that technology is improving and those cups are now turning into buckets.