I’d not heard of porpicide before, but it seems that it’s nothing new.
We think of dolphins as being intelligent, possibly the second most intelligent species on the planet, so I wonder if deliberate and intentional cruelty for fun and sport is one of the natural outworkings of intelligence? It would seem not unique to humans.
Not dissimilar to orcas ‘playing’ with seals and baby whales before killing and eating them. Ditto our cat (albeit on a somewhat smaller scale).
I see a fundamental difference in that the dolphins are not interested in the victim as food, and are doing it solely for fun.
Is it the difference between (a) having intelligence and (b) being moral beings? Or is there a distinction between animal intelligence (whatever that is, and I think it can be problematic when we anthropomorphise animal characteristics like intelligence) and empathy, so that the dolphins had no understanding of how the porpoise might feel?
Or cat has never managed to catch a baby whale let alone eat one 
Obviously it’s difficult to know. I am reminded in a way of school children who will brutally torture and harm other children without a care in the world, and yet if one were to present their behaviour to them without the presence of a supporting group, some would be quite horrified even though others would be entirely comfortable with what they’d done.
One might also ask if morality were a sign of intelligence. Creating a code for a society to live by almost certainly is, but what’s perceived as moral varies so much across humanity that I’m not sure there’s something human/intelligence sourced that we can point to as good, even though some do good
I’m afraid that intelligence has little to do with a person’s agressive behaviour towards others. One would hope that intelligence would bring self reflection but psychopathy not withstanding, there is clearly something switched off in some people’s brains.
In the case of the dolphin attack, is it not ‘just’ competition over dwindling fish food?
My understanding is that the dolphins just enjoy hurting the victim, though like a teenager tieing fireworks to a cat, they may not have an internal perception of suffering on the part of the porpoise.
Yikes! I truly hope not merely for enjoyment of another’s fear and pain.
Maybe more creatures than human have brains with psychopathic deformities. Born this way, or bent by something?
Ah, but has it ever had the opportunity?
She will soon if DFDS don’t let her on the ferry (qv cat passport thread)