The underwater world is home to some crazy marine life; from the parasite that lives solely on the Greenland shark’s eyeball, to the tail whip hunting techniques of our favourite thresher sharks. Leaving behind our terrestrial home for an underwater excursion can feel like visiting an alien world, with the suspension of ‘normal’ physics and all the special equipment needed to survive. It’s unsurprising that here we can come face to face with the closest thing we can find to an intelligent, alien lifeform. We’re talking about the cephalods.
The cephalopods include our many-limbed friends, the octopus and cuttlefish. The Greek name refers to the limbs around their head, from kephala meaning ‘head’ and podos meaning ‘feet’.
Apart from looking a bit strange, you’re probably wondering why we refer to them as ‘aliens’. All creatures with a nervous system and brain have evolved from the same common ancestor hundreds of millions of years ago, however, cephalopods are the exception. They branched away from the evolutionary tree before nervous systems developed. This means that nature has evolved two entirely separate brains, nervous systems, and forms of intelligence. When you stare into the eyes of a cephalopod, you’re meeting an incomprehensible intelligence. Of course, scientists are trying to decipher this mysterious mind, but devising intelligence tests for an alien is tricky. Consider an octopus judging how clever you are, by cutting off an arm and seeing how many colours you can change it in 30 seconds!
Octopus have 3 hearts, blue blood, and no central brain, with a net of neurons instead covering their entire body, allowing each arm a good amount of autonomy. As nocturnal hunters, these are diver favourites to watch fluidly sneaking across the seafloor. You have to be eagle eyed and lucky to spot one, but day sightings of octopus around Malapascua are not unusual, with reef octopus often gracing night dives and the occasional blue ringed octopus providing a special treat for some divers. At our very own house reef there have even been recent sightings of a wunderpuss and a starry night octopus!
Cuttlefish are more common sightings around our divesites, especially the large broadclub cuttlefish. Often found in pairs, they are not afraid to put on a display for divers, and stay close enough to curiously observe us as we watch them. With rapidly changing colours, patterns, and raised papillae, one individual can appear completely different from minute to minute. They can be seen mating, fighting, and hunting before effortlessly cruising away with their jet propulsion.