If you’ve ever wondered how and why ‘sucker fish’ hitch a – usually – wild ride with a humpback whale on the move, new footage captured from camera-tagged whales reveals the secret lives of remoras, and just how dedicated these hangers-on really are.
Dr Olaf Meynecke, a Griffith University marine scientist and co-leader of the Whales and Climate Research Program, captured several videos of remoras (commonly referred to as ‘sucker fish’) hitchhiking on migrating humpback whales along the East Coast of Australia during his regular fieldwork season.
Dr Meynecke routinely deploys suction camera tags to monitor the behaviour and migration patterns of humpback whales, and knows remoras are always likely to be in the frame as they spend their life attached to whales – not just for the ride but also for food.
“I think one of the biggest surprises when we investigate videos captured from our tags was the remoras’ ability to move around freely and keep returning to the whale’s body, even during very fast ascents to the surface and immediately after the whale breaches and returns to the water,” he said.
“We have also been able to observe a remora ingesting whale skin, suggesting that at times, when other ectoparasites were not available on the whale, they took advantage of the whales constantly shedding their skin.
“It was amazing to see how fast and nimble they were during several different rides with the whales.
“They seem to have developed an adaptation to hydrodynamics – they don’t actually create a suction, the plates on top of their heads create a vacuum effect that helps them almost adhere to the whales, plus they grip to the whales body using their modified dorsal fin.”
Dr Olaf Meynecke
Some species of remora such as the ‘whale sucker’ (Remora australis) preferred whales as their host but they were also seen riding under sharks, manta rays, dolphins, turtles, and dugongs.
They have even been known to attach themselves to boats and scuba divers.
“Remoras are harmless and are not a parasite to the whales; in fact, they can benefit the whale by removing sea lice and other crustaceans wanting to settle on the whale’s body,” Dr Meynecke said.
“However, they do seem to be in much higher numbers – about 15-20 remoras per whale – with whales that appear to shed more skin.
“In some cases, we saw as many as 50 remoras on a single whale.
“Even though they are likely beneficial for the whales, as they eat other host organisms such as sea lice, the whales seem to dislike their presence.
“We have observed whales eyeing them, undertaking multiple breaches then checking again.”
Dr Meynecke said the footage provided rare and interesting insights into some of the relationship quirks between whales and remoras, but there were still mysteries around the remoras’ behaviour and movement patterns.
“We don’t know if the remoras also head down to Antarctica with the whales – some may, but we don’t know how long they’ll attach themselves to a specific host,” Dr Meynecke said.
“There is also the interesting life cycle of remoras.
“Their spawning takes place in the East Australian Current, then the little larvae develop to tiny suckerfish but have to then find a host.
“That could suggest the time of reproduction could be linked to the whales’ migration cycle.”