A whale shark suggestions nostril down, holds its tail nearly nonetheless, and sinks. The digital camera watching that is clamped to the vanguard of its dorsal fin, roughly 1.5 to 2 metres behind a mouth it can’t see. What the lens does catch is the gill slits, flared open on the best way down.
Throughout the 4 sharks whose motion knowledge could possibly be used, that descent runs at a imply physique pitch of about twelve levels and a median sinking velocity of slightly below a fifth of a metre per second. The researchers name the behaviour gliding gradual feeding, and it’s considered one of six feeding behaviours their paper describes as novel. Behaviour the crew scored as feeding was filmed from the floor right down to 68.8 metres.
The work is an ethogram for the whale shark, printed open entry in Marine Biology on 21 July 2026 by Christine Barry of Murdoch College and the Australian Institute of Marine Science, with six co-authors. An ethogram is a list: a regular checklist of an animal’s discrete behaviours, written so completely different analysis groups can rating the identical factor the identical method. The paper is typed on publication as “Assessment, idea, and synthesis”, and 30 of its 36 entries come from different folks’s printed work.
A fin clamp, a spotter aircraft and a galvanic hyperlink
A spotter aircraft discovered the sharks in Norwegian Bay, at Ningaloo Reef in Western Australia, throughout Might of 2017 and 2018. Snorkellers went in from an 8.4 metre vessel and stuck a digital camera tag to the vanguard of the dorsal fin with a minimally invasive clamp.
Every tag carried a VHF transmitter, and a Fastloc GPS tag linked to the digital camera by a wire hint about 1.5 metres lengthy. A galvanic hyperlink was configured to interrupt and launch the package deal after roughly 24 to 48 hours. The digital camera recorded a 30 minute interval each hour from daybreak to nightfall, about 06:00 to 18:00, whereas depth was logged constantly at ten readings a second.
Tags went onto ten whale sharks and 5 produced usable footage. The paper attributes the shortfall to unspecified technical points, plus tags dislodging after deployment and particles accumulating on the lens. Depth and accelerometer knowledge from one of many 5 surviving sharks had been additionally excluded, so the kinematic figures relaxation on 4 animals and about eighteen hours.
What remained was 45 video intervals totalling 22 hours and 27 minutes, from two females and three males measuring 4.5 to 7 metres. Towards that, the crew ran a Google Scholar search in August 2025, screened the primary 200 outcomes for every of three search phrases, and saved 106 articles out of 600. The factors had been slender: a particular description of a behaviour instantly noticed or recognized from kinematic knowledge, in English, peer reviewed other than one thesis as a result of be printed, with behaviours inferred from two-dimensional dive profiles thrown out.
A dorsal fin sits two metres from a mouth
The digital camera’s place units the restrict on all the things that follows, and the paper states the issue earlier than it reviews a consequence. Mounted on the dorsal fin, the digital camera couldn’t instantly movie the mouth opening and shutting beneath the snout. So the crew learn feeding off the gill slits as a substitute, treating flared slits and open gill arches as a proxy for water and prey shifting via an open mouth.
That proxy is just not unique, by the paper’s personal account. The ethogram entry for fluttered gills notes that the motion happens throughout non-feeding in addition to throughout each feeding modalities, and the paper concedes that gill actions in fishes should not uniquely diagnostic of feeding. The crew assumed gill arch rotation mirrored feeding relatively than an effort to tackle extra oxygen, and says this can’t be decided definitively. It does provide assist: the water at Ningaloo is nicely combined and the observations sit shallower than 70 metres, the place sturdy hypoxic influences are unlikely, and gill clearing occasions got here with a visual particulate plume 44 instances throughout feeding towards twice throughout non-feeding.
No prey merchandise was identifiable in any of the footage, due to the sector of view, the digital camera high quality, visibility and the velocity of the animal.
The rely of latest behaviours is softer than a single quantity suggests. The summary says six novel feeding behaviours. The outcomes part reviews 13 behaviours on video, 5 of them beforehand not described within the literature. The dialogue names seven novel behaviours, six feeding and one locomotory. Of the six the dialogue calls novel feeding behaviours, three are credited within the ethogram desk to this examine alone. The opposite three checklist this examine first alongside a previous supply. One concedes the behaviour is probably going the identical as one thing one other crew already reported in 2020. One factors to earlier floor dives. One holds solely on the belief that the sharks weren’t doing a unique factor on the time. And sea ground scratching, additionally credited solely to this examine, is just not counted as novel wherever within the paper.
Many of the footage is a shark consuming gently
The paper types feeding into three classes borrowed from earlier work, renaming considered one of them. Feeding is lively, stationary, or gradual. Gradual feeding is the class that took up extra of the recorded time than every other.
Floor gradual feeding was probably the most prevalent behaviour of all. Water column gradual feeding got here second, shut behind. Cruising, which the ethogram doesn’t rely as feeding, was third, at a median of 16 per cent of the recorded time. Gliding gradual feeding ran to a imply of 6 per cent of the recorded time, towards 1.3 per cent for plain gliding, the place the gills keep largely closed.
Imply depths separate the behaviours even the place particular person occasions overlap. Benthic gradual feeding, by which a shark swims alongside the seabed with a horizontal physique and filters, averaged 46.4 metres. Water column gradual feeding averaged 32.7 metres and reached 68.8. Gliding gradual feeding averaged 31.6 metres. Floor gradual feeding averaged 2.7 metres. The longest gliding descent recorded fed from 5.2 metres right down to 64.7, and the longest ascent fed from 65.2 metres again as much as 1.7.
Two limits journey with these figures. The cameras ran in daylight solely, roughly 06:00 to 18:00, so nothing right here speaks to what these sharks do after darkish. And the animals had been 4.5 to 7 metres lengthy, towards a species most the paper elsewhere offers as 18 metres, with no methodology said for a way size or intercourse was decided and no maturity class assigned.
The mechanical argument the paper builds on the footage is about price. Earlier research have measured whale shark gape various from 50 to 85 per cent open relying on the behaviour, and the paper argues {that a} variable gape means variable drag, so a shark can scale the value of a mouthful to the prey really out there. Ram-filtering whales such because the bowhead and the North Atlantic proper whale feed with the mouth both open or shut, and printed figures put their drag penalty at sixfold and at two to 5 instances. Each a type of numbers is quoted from earlier work. This examine’s digital camera couldn’t see a mouth in any respect.
Basking sharks managed one feeding behaviour in 123 hours
The comparability the paper returns to is with one other big filter feeder. In 123 hours of towed digital camera video from six basking sharks, a 2021 study recorded feeding of a single form, all of it inside a metre of the floor, and three of the six had been by no means seen feeding in any respect. Eight feeding behaviours turned up in 22.5 hours right here.
The paper explains the hole two methods, and anatomy comes first. Whale sharks are orectolobiforms whose family members use suction; basking sharks are lamniforms, with much less jaw mobility and fewer management of the buccal cavity for filter feeding. Web site-specific prey could matter too, alongside real foraging plasticity, and the paper notes that basking sharks are recognized to observe prey right down to depth, so additional behaviours could but be described for them. It doesn’t modify for the more-than-fivefold distinction in effort between the 2 datasets.
The summary’s closing claims are hedged. Whale sharks could feed in a cheap method throughout a really broad vary of prey densities, in distinction to baleen whales and basking sharks that restrict feeding to dense aggregations of prey. That flexibility could also be a key attribute permitting these giant filter feeding sharks to outlive in tropical water carrying little meals. The primary of them additionally asserts flatly that the ethogram revealed whale sharks forage utilizing completely different feeding sorts and actions.
A shark can tilt nostril down at twelve levels, maintain its tail nearly nonetheless, sink at 0.18 metres per second with its gill slits flared, and nonetheless be consuming, thirty metres down.
