Study Reveals Unique Ability of Seahorses to Snag Prey at Exceptional Speed
rael-science
Researchers at Tel Aviv University have discovered that seahorses can move their heads up at the
extraordinary speed of 0.002 seconds when they were analyzing the
unbelievable preying capability of seahorses. The fast head movement
happens together with a robust flow of water that snags their prey
straight into their mouth.
A short-snouted seahorse clinging to coral in the Red Sea. Image Credit: Gil Koplovitz. The research was headed by Prof. Roi Holzman and the doctoral student
Corrine Jacobs of the School of Zoology at the George S. Wise Faculty
of Life Sciences and the Steinhardt Museum of Natural History at Tel
Aviv University and was carried out at the Interuniversity Institute for
Marine Sciences in Eilat. Details of the study have been published in
the Journal of Experimental Biology.
The scientists describe that seahorses are fish that possess
exclusive properties such as square tail vertebrae, male “pregnancy” and
the undeniably exceptional eating system. During the day, seahorses
tend to stay anchored with their tail to corals or seaweeds with their
head tilted in a downward direction, close to their body. But when they
spot prey moving over them, they lift their head at unbelievable speed
and capture it.
According
to Prof. Holzman, when seahorses prey, they turn their body like a
spring: using their back muscles, they stretch an elastic tendon and
utilize their neck bones as a “trigger,” similar to a crossbow. The
outcome is faster than even the quickest muscle contraction seen
anywhere in the animal kingdom.
However, so far it has not been clear how the spring-loaded
contraction enabled seahorses to eat. Just like anyone who tries to
remove a fly from a cup of tea understands, water is a viscous medium
and the fish has to open its mouth to produce a flow that pulls the prey
in. Now the question is, do seahorses synchronize snagging in prey
using their head movement?
In their latest study, the Tel Aviv University scientists were
successful in precisely describing and quantifying the movement of the
seahorse by photographing their attack at a speed of 4,000 images per
second and using a laser unit for imaging the water flows.
This measurement revealed that the “crossbow” system has twin
purposes: allowing head movement and producing high-velocity suction
currents — 10 times faster than the movement of fish of similar size.
Their unique advantages allow seahorses to catch especially elusive
prey.
The new measurements also help provide insights into the ecology of
several species of seahorses, differentiated from each other by their
nose size.
Our study shows that the speed of head movement and suction currents are determined by the length of a seahorse’s nose. From the evolutionary aspect, seahorses must choose between a short nose for strong suction and moderate head raising, or a long nose for rapid head raising and weaker suction currents.
Prof. Roi Holzman, Study Lead, Tel Aviv University
“This choice, of course, corresponds to the available diet:
long-nosed species catch smaller, quicker animals whereas short-nosed
species catch heavier, more ponderous ones,” he added.
Prof. Holzman believes that seahorses are not the only example of the
remarkable spring mechanism. In fact, seahorses are members of the
Misfit Fish family, including species such as shrimpfish, alligator
pipefish and flutemouths or cornetfish.
These fish are called that because of their odd shape which enables stretching their body into a spring. The big question applies to the evolution of the spring mechanism, how it was formed and when it developed. I hope our recent study will lead to further studies designed to help solve the riddle of spring fish.
Prof. Roi Holzman, Study Lead, Tel Aviv University
Journal Reference:
Knight, K (2021). Rearing seahorses trigger powerful gulps. Journal of Experimental Biology. doi.org/10.1242/jeb.243282.
Source: https://english.tau.ac.il/