Marine biologist Tom Hird, known as “The Blowfish,” says that if octopus brain structure had evolved differently, cephalopods might be the dominant species on Earth instead of humans. He also highlighted the extraordinary lifecycle of the deep-sea hairy anglerfish and other ocean marvels.
Ocean is loud, not silent
Mr Hird, who performs as “The Blowfish,” said one of the biggest misconceptions about the sea is that it is quiet. “The loudest animal on the planet is found in the ocean, and there are animals in the ocean that can kill using sound, so it's a very active and audible area,” he said.
Underwater noise is not simply a problem for whales and dolphins trying to communicate. Sound can determine whether damaged coral reefs recover at all. Mr Hird said studies in Australia had shown the remarkable effect of playing recordings of healthy reefs through underwater speakers.
“In areas of reef that were previously destroyed or degraded, researchers set up underwater speakers and played the sounds of a healthy reef on a loop,” he said. “The number of fish that then came to that reef was very significant, allowing previously damaged reefs to start to recover.”
It creates a vicious cycle when a reef falls silent. “If a reef gets damaged, it sounds less active, so fewer fish come to it, making it even less active, and so on and so forth,” Mr Hird said.
Sound as a sixth sense
The noises involved are not necessarily dramatic. Grunts, pops, scrapes and other tiny sounds can act as a biological advertisement that tells fish a reef is alive and worth investigating. Human activity can drown those signals out.
And sound underwater is about much more than hearing. “The wonderful thing about sound in the water is that, as far as physics is concerned, sound is just pressure waves,” Mr Hird said. “It doesn't matter if it's in the air or in the water: sound is pressure waves.”
For creatures such as sharks, those pressure waves can effectively provide another sense. “A single sound source from potential prey can give off multiple signals that something like a shark can use - not only to listen to, but to detect, feel, and gain an extra sixth sense from,” he said.
Deep-sea adaptations
Then there is the extraordinary business of surviving the crushing pressure of the deep. Mr Hird described deep-sea fish as becoming more “liquidy” - their tissues containing more fluid so they can withstand immense pressure. “Their tissues and bodies contain more fluid so the pressure can't crush them as easily,” he said.
Bring them rapidly to the surface and that adaptation can become a liability. “When you bring them up to the surface - like the classic blobfish - they don't have that structural support anymore because their body is essentially liquid, so they expand,” Mr Hird said.
Other creatures have evolved adaptations that sound almost like science fiction. Take the stoplight loosejaw. Red light disappears rapidly as it travels through seawater, meaning a red animal can become effectively invisible at depth. But the loosejaw can produce red light from specialised organs on its cheeks.
“If you produce red light at depth onto an animal that is red, it lights up like a neon sign!” Mr Hird said. “This animal swims through the ocean with its red high beams on, illuminating anything it passes over. Nothing else can see the red light because nothing else is looking for it, so the loosejaw can just snipe its prey.”
The anglerfish's strange life
Mr Hird also highlighted the extraordinary reproductive strategy of the deep-sea hairy anglerfish. The female can be around the size of a small watermelon, while the male is tiny - roughly an inch long - and looks completely different. For years, scientists even believed they were separate species.
“The males are essentially just a tail with an enormous nose to sniff out females. When a male smells a female, he swims straight to her over vast distances, bites her, and latches on for the rest of his life,” Mr Hird said.
He said the male then begins to degenerate, losing his eyes, most of his internal organs and his fins before fusing with the female's body. “He receives nutrients through her blood, and functions essentially as a packet of testes. That is his entire life!” Mr Hird said.
Several males can attach themselves to a single female. “A healthy female might have three or four attached, allowing her to sample sperm from different males,” he said.
Whales and the deep
Mr Hird said over 90% of the ocean is a mile deep, yet the deepest humans go in saturation diving is about 200 to 300 meters. Even the deepest-diving mammal, the Cuvier's beaked whale, has been recorded reaching around 1.6 kilometres — barely a scratch compared with the Challenger Deep, which plunges more than 11 kilometres.
For whales, avoiding decompression sickness involves another remarkable adaptation. “Before a deep dive, they exhale to expel most of the air from their lungs,” Mr Hird said. “The small amount of air they retain is kept in crucial airways, while the rest of their lung structure is allowed to collapse.”
Rather than continuously breathing compressed air like a human diver, a whale takes a single breath before descending. As pressure increases, its lungs collapse in a controlled way, limiting the absorption of nitrogen and helping prevent the potentially deadly bubbles associated with “the bends”.
Sharks and solar-powered slugs
Mr Hird said the creatures most important to the ocean are not necessarily the ones that make spectacular television. Krill, he said, play “a phenomenal role” because of their huge numbers, their place in food webs and their contribution to carbon cycling. But his own choice for the ocean's most misunderstood essential worker is the shark.
“Sharks are the caretakers of our oceans,” Mr Hird said. He said sharks acted as “the regulators and umpires of the sea”, with different species maintaining balance throughout ocean ecosystems.
Some sea slugs can steal chloroplasts — the structures plants use for photosynthesis — from algae they eat and retain them in their own bodies. “They route these chloroplasts into fleshy lobes on their backs, turning themselves into solar-powered organisms that generate their own carbohydrates through photosynthesis,” Mr Hird said.
The octopus 'what if'
But perhaps the strangest evolutionary “what if” concerns one of the ocean's most famous inhabitants: the octopus. Humans and octopuses travelled down radically different evolutionary paths. “We share more evolutionary traits with almost any land creature than we do with an octopus; they represent a truly alien line of evolution,” Mr Hird said.
Their brains are ring-shaped, with the oesophagus passing directly through the centre. “Because their food passes through their brain ring, they must liquefy everything they eat; swallowing anything too solid could physically damage their central nervous system,” Mr Hird said.
And their intelligence is distributed in an extraordinary way. “Two-thirds of its neurons are distributed throughout its arms in local nerve clusters,” Mr Hird said. Each arm can process sensory information, taste and make movement decisions independently, while remaining connected to the central nervous system.
“An octopus operates almost like nine interconnected minds: eight arms autonomously exploring and reacting to their environment, alongside a central consciousness,” he said.
It raises a tantalising evolutionary possibility. “If evolution had configured their brain structure differently without that constraint, cephalopods might be the dominant species running the world today instead of us,” Mr Hird said.
Mr Hird will explore those adaptations in Heavy Metal Marine Biology, his New Scientist Live show as “The Blowfish” — the self-described world's only heavy metal marine biologist — combining music, humour and science to challenge the idea of what a scientist is supposed to look like. “You don't have to fit a traditional mold to do biology; you can have a giant beard, love heavy metal, and still share serious science,” he said.
