Fish can bend their heads up like animals on land, but have to bend their entire spines

Fish can bend their heads up like animals on land, but have to bend their entire spines, X-ray shows

  • Fish can tilt their heads upwards by bending their spines – similar to a person
  • Rainbow trout and frogfish can normally have their heads between 20-30°. to spin
  • Trout tend to turn less than 3° and use a third of their joints to lift their heads
  • Frogfish can turn 20 to 30° to lift their heads with their first joint
  • On their tips, trout can turn their heads 18.6° and angler fish up to 56°


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This gives new meaning to the expression, ‘keep your head on a swivel’.

A researcher at the University of Liverpool has found that fish can tilt their heads upward by flexing their spines – similar to someone lifting their head with their necks – despite the simple fact that they are built completely differently from land animals.

dr. Ariel Camp looked at the motion of the spine in rainbow trout and anglerfish using X-rays and digital animations and found that they can normally rotate between 20 and 30 degrees.

Trout tend to turn less than 3° and use a third of their joints to lift their heads

Frogfish can turn 20 to 30° to lift their heads with their first joint

Frogfish can turn 20 to 30° to lift their heads with their first joint

Fish can tilt their heads upward by bending their spines — similar to a person, a new study has found

“Instead of just using the vertebral joints directly behind the head as a human would, these fish arched up to two-thirds of their spines when lifting their heads to eat,” said the study’s lead author, Dr. Ariel Camp, in a pronunciation.

“This shows that fish move their spines three-dimensionally as they swim and eat, which helps us understand the evolution of the spine — and especially the neck — in vertebrates.”

Camp noted that trout have small — usually less than three degrees — dorsal rotations for a third of their joints to lift their heads.

On average, the fish can normally turn their head between 20-30°.  to spin

On average, the fish can normally turn their head between 20-30°.  to spin

On average, the fish can normally turn their head between 20-30°. to spin

Frogfish, however, can rotate 20 to 30 degrees to lift their heads with their first intervertebral joint, but have small rotations over the rest of the vertebrate.

On their tops, however, the trout were able to turn their heads up to 18.6 degrees, while some angler fish could turn up to 56 degrees.

Tetrapods (or four-limbed animals) use their necks to move their heads in a three-dimensional manner relative to their bodies and limbs.

Since fish don’t have necks, it was thought they couldn’t.

At their peaks, trout could turn their heads up to 18.6 degrees, while some angler fish could do it up to 56 degrees

At their peaks, trout could turn their heads up to 18.6 degrees, while some angler fish could do it up to 56 degrees

At their peaks, trout could turn their heads up to 18.6 degrees, while some angler fish could do it up to 56 degrees

However, Camp saw this movement while feeding, when many species lift their heads relative to their bodies.

The head lift is believed to arise from “the craniovertebral and cranial most intervertebral joints acting like a neck, by rotating (extending) dorsally,” she added.

The head lift is believed to arise from “the craniovertebral and cranial most intervertebral joints acting like a neck, by rotating (stretching) dorsally,” Camp said.

‘Unlike tetrapods, fish rotate large areas of the spine to turn the head,’ explains Camp.

“This suggests that both cranial and more caudal vertebrae should be considered to understand how non-tetrapods control movement at the head-body interface.”

The study was published today in Proceedings of the Royal Society B: Biological Sciences.

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