Firstly, this is a philosophical text and not a scientific text, so it's quite light on science and heavy on philosophical speculation.

The author uses their interest in marine life to contemplate consciousness and the divide between the physical (tangible) and non-physical (intangible) self.

I really enjoyed the author's other work - "Other Minds" - however, I found this particular work to be somewhat aimless and less cohesive.

I also found the author's ideas to be somewhat unformed and wishy-washy.