A squid-like organism uses gravity powered flight but relies on jet propulsion for launch, pouncing, and evasive tactics.

It’s aerodynamically based on the way a true squid flies however it has evolved atmospheric jet propulsion to replace the constricting hydraulic jets.

**Real squid currently fly like this, with water jets:**

![flying squid](https://scx2.b-cdn.net/gfx/news/hires/2013/imagetakenby.jpg)

[I have already found a solution to cooling](https://worldbuilding.stackexchange.com/questions/159389/help-cooling-living-h-2-fueled-pulse-jet-engine) so **it can now fly like this:**

![](https://i.stack.imgur.com/iosE7.jpg)
But it needs to charge the conflagration chamber then ignite it quickly after leaving the water. That timing is a different question; this one focuses on a gland or faculty that generates and manages the ignition chemistry.

About the creature:
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It’s tentacles and fins have become much larger for sustained flight, two tentacles have become wings [with a 10-foot wingspan](https://worldbuilding.stackexchange.com/questions/159569/what-would-be-the-wingspan-and-lifting-surface-area-for-a-5kg-canard-configurati) (4 foot wings) which lock in their extended position when they jump out of the water. It’s other arms remain articulate for grappling and marine locomotion.

The jet deflagration chamber is the scavenged nearly perfectly flared cylindrical exoskeleton of another mollusk, with a diameter acoustically tuned to an OH deflagration cycle. This squid binds it to its body, having an intake on the nose and exhaust from the posterior of the animal. The material is unlikely keratin or calcium carbonate, it needs to have good thermal insulating properties and structural integrity.

The jet fuel is twofold: H gas is a natural fermentation byproduct stored in bladders; a symbiotic algae lives in a layer under its translucent skin, consuming its respiratory exhaust and producing O$\_2$ which collects in another bladder. The two gasses are injected into the unvalved deflagration chamber for propulsion.

The jet only needs to run for 2-second bursts of possibly 8 - 12 pulses. It’s purpose is to simply gain enough momentum to get airborne, or evade a predator while in flight.

Assume the animal’s total gross weight is 5kg, and it can accelerate at 8 ms$^{-2}$ for two seconds. This flight is expensive, like a jaguar's chase, so they try not to waste this flight. Recharging their jet can take hours, or days without the right conditions.

Given the 960J of heat generated by this reaction, [as calculated by Starfish Prime](https://worldbuilding.stackexchange.com/questions/159389/help-cooling-living-h-2-fueled-pulse-jet-engine/159390#159390), and the 2-second burst requirement to reach cruise speed;

What biological ignition system could spark the O$\_2$ & H fuel pulse jets most reliably?
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The spark can be from chemistry synthesized by the animal, or generated by a symbiotic relationship, or harvested from the environment; but it must be a true exothermic ignition reaction.