Disclaimer: Refer to "The Dogfish Sharks".
This is my first shot at a flashback chapter; a chapter that takes place before the beginning of the series. If you guys like this, I can certainly do more and flesh out the history of the Octonauts.
Note that during the past portion of the story, italics are to indicate dialogue from the present.
BKPSDITTEKDL
It was a cool evening under the sea. Captain Barnacles was going around the Octopod, making sure everything was in order, when he heard laughing coming from the Game Pod. He went to investigate and found the younger Octonauts gathered in there with blankets and pillows, in a pseudo-sleepover sort of event, watching Kwazii do a funny pirate dance. Just as he finished, he noticed the captain standing behind him. "Uh, evening, Captain."
"Good evening," said Captain Barnacles. "Why are you all sleeping on the floor in here?"
"Uh, Deborah suggested we could have one of those sleepover things, sir," said Elekai.
Captain Barnacles cocked an eyebrow. "Alright…"
"Kwazii was telling us a funny story from his pirate days," said Tweak.
"I see," said Captain Barnacles. "You know, I have a lot of good stories from when I was young." He saw everyone's eyes widen in curiosity. "Do you want to hear one?" They all nodded in unison. He chuckled and pulled up a chair while the younger Octonauts all crowded around him.
RCVANIB (blast to the past)
"It was many years ago, back when I was only a junior lieutenant."
Twenty-nine years in the past, the Octo-Base was stationed off the coast of Western Australia. Young Barnacles was stationed in HQ.
"I was being trained with the computers by the communications officer, Niall."
"This button activates manual steering," said Niall. "The captain uses this when the ship is out of control and the regular controls aren't working."
Almost on cue, Captain Riviera came into HQ. "How are things going along here, Niall?"
"Very good, Captain," said Niall. He checked the water outside. "Hmm…the water outside is abnormally salty."
"Just then, we saw a snake swimming around in the shallow water close to the surface, flicking its tongue about."
"That little fella seems to enjoy it," said Barnacles.
"We should investigate," said Captain Riviera, going down to the Launch Zone.
"So Captain Riviera took her finest crewmates out to find that snake."
RCVANIB
Outside, Captain Riviera, alongside her lieutenant Caspian and field researcher Atlantis, swam into the shallow waters to find the snake. They found him slithering towards the surface for air. The Octonauts followed his lead and came up to land on an island near the Ashmore Reef. Imagine that snake's surprise to see a Rottweiler, mountain cat, and badger looming over him!
"Don't be frightened, little fella." Captain Riviera said to the snake. "We're the Octonauts. Who are you?"
"I'm a short-nosed sea snake," said the snake, "but you can call me Shorty."
"Short-nosed sea snake? Those haven't been seen in almost twenty years! You met a species believed to be extinct and I never heard about it?!"
"Yes, Shellington, now settle down and listen."
"Oh…okay."
"We saw you flicking your tongue in the water," said Caspian.
"Well, of course," said Shorty. "It's salty. I love salt."
"Of course!" Atlantis exclaimed. "Short-nosed sea snakes have a special gland under their tongues that absorbs excess salt from seawater."
Captain Riviera noticed that Shorty was itching and wiggling. "Are you alright?"
"Fine," said Shorty. "I'm just gonna be moulting soon."
"Spellbinding! I've never seen this type of snake moult before," said Atlantis. "Is it alright if we take you back to the Octo-Base?"
"Octo-Base?"
"It was our first home, before the Octopod."
"Eh, I don't see why not," said Shorty.
Captain Riviera nodded and took out her Octo-Compass. She pressed the Octo-Alert button.
"Octonauts, to the HQ!"
The Octo-Alert blared throughout the Octo-Base, and all of the Octonauts rushed to HQ.
"Octonauts, this is Shorty the short-nosed sea snake."
"Howdy," said Shorty.
"He's going to moult soon, and we've invited him to stay here while he does so."
RCVANIB
"We brought the snake to the Octo-Base's lab."
In the lab, Shorty was placed in a tank, where he began to wiggle out of his old skin. Atlantis, Barnacles, and the medic Verdun watched, intrigued. After some squirming, Shorty was free of his old layer of skin.
"Enchanting!" Atlantis was furiously writing down notes on her notebook.
"Why did Atlantis always talk like it was magic and not basic science? I've always found that odd."
"Are you going to interrupt every two minutes?"
"...No, sir."
Verdun picked up the old skin. "'Is skin is scaly."
"I'm a snake," said Shorty. "That's how our skin is, buddy. I'm mostly brown, but see, my buddy Pipsqueak, now she's a sight. She's got purple scales."
"Scaly, 60 centimeters, lives in Australian waters, brown or purple…" Atlantis looked over all of her notes. "This is great research!"
"Well, I'm glad I could help you, ma'am," said Shorty.
RCVANIB
Later that day, after Shorty had left to go back to his home, the Octonauts were gathered in HQ, where Atlantis was excitedly adding all of the information she learned that day to her creature book.
"Today was a good day for you, eh?" Caspian asked.
"Of course," said Atlantis. "My hope is that when my time with this team is up, the next field researcher will inherit this book and will have all the information I found about creatures they may never get to see."
"I hope zat ze next field researcher aboard zis ship is, how you say..." Verdun paused and mumbled to himself in French for a moment. "...magnificent."
BKPSDITTEKDL (back to the present)
"It's not the most exciting story ever…" Captain Barnacles' voice trailed off as he noticed that all of the younger Octonauts were sound asleep. He smiled and lowered his voice. "But I'll never forget how happy Atlantis was that night, and I'm very glad that she got her wish. Good night." He got up and left the Game Pod.
RCVANIB (old school Creature Report!)
"Calling all Octonauts!"
"Caspian!"
"Verdun!"
"Atlantis!"
"Niall!"
"Inkling!"
"Barnacles!"
"Full attendance! Caspian, activate Creature Report!"
"Creature Report, Creature Report!"
"Places, everyone! Facts: Short-nosed sea snakes love salt."
"Check!"
"Check!"
"Check!"
"Their tongue glands help to collect it all."
"Check!"
"Check!"
"Check!"
"Every month or so, they start to shed…" (Creature Report, Creature Report)
"…and get new skin from tail to head." (Creature Report, Creature Report)
"Australia is where they're found…"
"Check!"
"Check!"
"Check!"
"Two hours under water till they have to get to ground!"
"Dance break!"
(insert dance break here)
"Go snake! Go snake! Go snake! Creature Report, Creature Report!"
"We're done with our mission! Octonauts, at ease, until the next adventure!"
BKPSDITTEKDL
Information about the short-nosed sea snake taken from Australian Geographic
Information about Ashmore Reef taken from Wikipedia