Fishing is time-consuming business, so diving birds in Mexico's Baja California are frequenting the local "sushi conveyor" instead. That conveyor comes in the hulking shape of the region's reigning big fish: the whale shark. The crafty cormorants have figured out that the giant sharks provide an endless supply of remora sashimi.


In the clip, a diving cormorant yanks furiously at a remora fish attached to the skin of a passing whale shark, before finally pulling its meal free. It's a truly remarkable sighting – in fact, this footage filmed back in 2012 may be the first (and only) example of its kind. According to marine biologist Dr Simon Pierce, who has done extensive work on whale sharks, experts have been excitedly discussing the video since it started making the rounds online earlier this week.

"It's super cool!" he says. "I don't think it's been documented. I've never seen or heard of it previously, but that particular cormorant certainly knew what it was doing. Smart bird!"

An extended clip released by Manta Scuba Diving confirms the event was no once-off: after its initial catch, the bird – likely a Neotropic cormorant or double-crested cormorant (Phalacrocorax brasilianus or Phalacrocorax auritus) – came back for both second breakfast and elevenses.

Remoras attach to their host species (animals like sharks, cetaceans and sea turtles, as well as the odd ship or human diver) using a slatted sucking disc located above the eyes. Once in place, the hitchhikers cruise along effortlessly, ready to gobble up any morsels that float their way.

The immense size of whale sharks offers particularly spacious real estate for remoras – some individuals cart dozens of the freeloaders around – so it's not entirely surprising that local birds have learned to capitalise on such an abundant food source.

Roominess aside, there's another reason remoras cling to whale sharks in such large numbers: poop. While it was long believed that the remora diet comprised mainly of their hosts' mealtime leftovers, scientists have since discovered that the suckerfish prefer to dine on something a bit more plentiful. And you don't get much more abundant than a whale-shark poop cloud: the animals can drop 56,000 litres in one go.

A post shared by WEDIVE.NO ( on Feb 18, 2017 at 7:35am PST

Forget privacy: there's nothing like a feeding frenzy to interrupt toilet time.

Without data from additional documented sightings, it's impossible to say whether this remora-snatching behaviour is unique to cormorants in Baja, or even to this individual bird – but we suspect the latter scenario, at least, is incredibly unlikely. The strategy has been seen in other species before, so it stands to reason that seabirds might employ this tactic more often than we think. 

Sea lions in the Galapagos Islands, for example, have been known to pluck the occasional "shark sucker":


Unlike sea lions, cormorants can stay beneath the waves for only about 70 seconds, which limits the "ground" they can cover during each predatory dive. A single catch might mean lengthy chases and multiple return trips to the surface, so the "whale-shark method" could save the birds a good deal of energy.

The word "remora" means "hindrance" in Latin, and some animals (namely dolphins and basking sharks) don't like to be dragged down: they repeatedly breach when enough of the fish take hold in order to dislodge them. Whale sharks, however, don't seem as fazed by the hitchhikers. And in fact, there may be some benefits to having a remora crew around: studies on their stomach contents have shown the suckerfish also scarf down parasites. 

Some commenters were curious to know whether the whale shark in the Baja clip may have been injured by the bird's repeated pulling, but Pierce suspects this was not the case. After all, whale-shark skin is among the thickest and strongest in the animal kingdom

"The whale shark might well feel it, when the suckerfish is firmly ensconced in the spiracle [the openings used to draw in oxygenated water] like that," says Pierce. "But no blood, no foul."


Top header image: Pixabay