How do puffer puffers get round?

本文同时提供以下语言的翻译:中文

Introduction

It is well known in the order Pufferidae that the bizarre ability to inflate the body is seen in all members of the families Tetraodontidae (pufferidae and trigger-nosed pufferidae) and disodontidae (Trigger-nosed pufferidae).
When they sense danger, they inflate quickly as a defense against predators (which makes it harder for predators to swallow their inflated bodies).
During expansion, a puffer expands rapidly by repeatedly pumping mouthful after mouthful of water or air into an expandable stomach.

So specifically from the physical point of view, how does the pufferfish get water expansion?
The chest band and head of puffed puffer had obvious changes and played a key role.

Take the puffer fish for example:
At the beginning of each expansion cycle (understandable into fugu each inhalation of water or air), buccal pressure drop associated with the activity of a few muscles (the period), these muscles make fugu mouth open (on muscle, muscle),
oppression hyoid organs (outreach hyoid muscles, chest hyoid muscle), chest belt and contraction (chest).
During buccal pressure, water is forced into the stomach;At this point the mandibular adduction (adductor mandibular), hyoid and pectoral muscles are drawn.


For ease of understanding, this process is analogous to the pump mechanism: when the pump is squeezed (negative buccal pressure), the volume of gas in the pump decreases with the volume of the pump.When the pump is released (positive buccal pressure) and the pump recovers, the pressure in the pump decreases,
and water enters the pump because of the pressure difference.

The ventral and lateral skin of puffer fish is highly stretchable, and the puffer’s lack of ribs allows it to withstand extreme shape changes.
The swelling behavior of puffer fish involves the special functional morphology of the head, which has highly active joints that allow a wide range of chest band extension and contraction.
And the well-developed abductor muscle, which can flex the joint between the first branchial bones, provides a new mechanism for buccal depression.


All in all, thanks to this special mechanism, most puffer fish are able to escape predators.Except for the ones kicked by dolphins.

Citation:
1.Wainwright, Peter C., and Ralph G. Turingan. “Evolution of Pufferfish Inflation Behavior.” Evolution, vol. 51, no. 2, [Society for the Study of Evolution, Wiley], 1997, pp. 506–18.
2.Wainwright, Peter C., et al. “Functional Morphology of Pufferfish Inflation: Mechanism of the Buccal Pump.” Copeia, vol. 1995, no. 3, [American Society of Ichthyologists and Herpetologists (ASIH), Allen Press], 1995, pp. 614–25.