The bustling pier square shimmered under the warm afternoon sun, a mosaic of laughter and leisurely strolls. Friends gathered in twos and threes, each breath imbued with the easy joy of the day. Amidst this vibrant scene, Popeye, Olive Oyl, and Professor Owl ambled along, their conversation a gentle murmur against the lively backdrop.

Suddenly, the cheerful hum of the square was pierced by a soft, pained whimper. Not far off, Little Squirrel was huddled on the ground, clutching his knee. His usually bright eyes were clouded with agony, his tiny brows furrowed so tightly they almost disappeared, and his face was a ghastly pale. Even his famously bushy tail, usually a plume of joyful energy, hung limp and dejected. This was not the lively, bouncy Little Squirrel everyone knew. In an instant, Popeye, ever swift to action, bounded towards him.

"Little Squirrel, what's got you so down?" Popeye knelt beside him, his voice gentler than his usual boisterous tone. "Is it... is it like that time my arm suddenly went queer? I just thought I'd overdone it with the heavy lifting, you know!"

Little Squirrel nodded, a tiny, miserable tremor running through him. His voice was barely a whisper, a faint mosquito's buzz against the buzzing square. "My knee... it just hurts and swelled up, Popeye. It's like a rock, and I can't move it an inch. I thought it'd just get better with a little rest, but it's been days now, and it's only gotten worse." A sniffle punctuated his words, a testament to his silent suffering.

By now, Professor Owl and Olive Oyl had reached them, their faces etched with concern. Professor Owl, ever the scholar, meticulously pushed his spectacles higher on his beak before slowly, gravely, squatting down. He extended a wing, its soft feathers brushing gently against Little Squirrel's swollen knee. The moment his wing made contact, a deep seriousness settled upon his wise face.

"Little Squirrel, listen carefully," Professor Owl's voice, though gentle, carried an undeniable weight of concern. "This is far more than just a bump or a fleeting chill. Your body, my dear friend, is very likely sounding an alarm—a 'warning signal' of an autoimmune disease. So many like you, little ones and grown-ups alike, dismiss these symptoms as minor aches, hoping rest will mend them. But to ignore these crucial signals, to delay understanding and treatment, is to gamble with your well-being. And that, my dear, is a gamble not worth taking!"

Olive Oyl, her hands gently steadying Little Squirrel, looked up at the Professor with genuine anxiety. "Professor Owl, what are these 'warning signs'? If only we knew what to look for, we could help our friends, so no one else has to suffer like poor Little Squirrel!"

With a soft flap of his wings, Professor Owl rose to his full height. He gestured towards a vibrant bulletin board standing proudly beside the square. "Aha! Perfect timing," he chuckled, a knowing gleam in his eyes. "Look, everyone! A 'List of Body Warning Signs' has just been posted, complete with clear illustrations. Let's go through them together, one by one. Pay close attention, for these are lessons worth remembering!"

He tapped a claw on the first item, his voice dropping to a serious, almost storytelling cadence. "First, we have persistent fatigue and weakness. This isn't the happy tiredness after a day of spirited play, mind you. This is an exhaustion that sinks into your very bones, a weariness that no amount of sleep or rest can shake off. Think back to our friend Popeye, not so long ago. He was so utterly drained, he couldn't even summon the strength to lift his own hand, let alone reach for his beloved can of spinach!" Professor Owl finished, gesturing towards a comical illustration.

All eyes turned to the bulletin board. There, an illustration depicted Popeye, slumped dramatically over a table, his head nestled on his arm, eyes barely slits, a picture of utter dejection. A forlorn can of spinach sat untouched before him, looking almost as sad as Popeye himself. The scene elicited a few sympathetic chuckles, even from Popeye. He scratched his chin, a sheepish grin spreading across his face. "Gosh, that's exactly it!" he boomed. "I even thought my spinach had gone bad, it was that bad!"

"Next," Professor Owl continued, his gaze drifting thoughtfully to Little Squirrel's throbbing knee, "we have joint or muscle pain and stiffness. This is precisely what our Little Squirrel is experiencing now. Joints become achy and swollen, especially noticeable in the quiet hours of dawn. You wake up feeling stiff as a board, needing to 'oil' yourself with movement before you can truly stretch out. And it's not just the big joints; even tiny fingers and wrists can fall prey to this discomfort." Little Squirrel offered a tiny, solemn nod. "Yes," he whispered, "every morning, my knee feels like it's glued stiff. It takes forever just to stand up straight."

Professor Owl continued, his voice taking on a graver note. "Third, we must consider unexplained fever. This isn't your typical high temperature from a common cold. It's often a low-grade fever, hovering persistently between 37.5℃ and 38℃, yet it refuses to budge. Crucially, there are no other tell-tale signs of infection—no coughs, no sneezes, no runny noses. And oddly, regular fever reducers seem to have no effect."

"Fourth, we look for abnormal skin conditions," he declared, pointing to an illustration of Little Duck, whose usually smooth feathers bore a distinctive mark. "Imagine Little Duck, or perhaps other friends, developing perplexing red rashes on their arms. These aren't just minor irritations; they often darken with sun exposure, becoming intensely itchy or even painful. Or consider those curious, butterfly-shaped red patches that might bloom across someone's cheeks. These, too, are urgent messages from your inner workings!"

A hush fell over the group as they absorbed the vivid illustrations. Popeye, his brow furrowed in thought, finally broke the silence. "Blow me down!" he exclaimed, thumping his chest gently. "So these little aches and strange marks... they're not just nothing! They're actual shouts from our own bodies! Are there any other signals we should be listenin' for, Professor?"

Professor Owl's smile returned, a knowing twinkle in his eyes. "Indeed, Popeye, the body has many ways of communicating! Beyond these, keep an eye out for: persistent dry mouth and tongue, a thirst no amount of water seems to quench; dry eyes, feeling gritty as if sand were caught beneath the lids, often accompanied by light sensitivity and excessive tearing; unexplained hair loss, where clumps seem to vanish without reason; and even sudden, significant weight loss, when you haven't even tried to shed a single pound. Each of these, in its own way, could be a whisper or a shout about an underlying autoimmune condition."

He then leaned forward, his voice firm and resonant. "Understand this, everyone: while many of these individual symptoms might seem common, even trivial, the key is their persistence. If fatigue or joint pain, or any of these signs, lingers for an extended period—say, for more than a week—you must, without delay, heed the warning. Do not simply 'hold on' and hope it vanishes. Your body is asking for help!"

Galvanized by Professor Owl's words, Popeye sprang to his feet. He cupped his hands around his mouth, his booming voice echoing across the lively square, carrying his message to every corner. "Ahoy there, everyone! Listen up, listen good!" he bellowed. "If you've got this pesky fatigue that won't quit, or joints that ache and swell, or a low-grade fever that just hangs around, or strange red rashes, or dry mouth and eyes, or hair falling out, or even just losing weight for no reason—you listen to me! Don't be a stubborn barnacle like Little Squirrel here! Get yourselves to Professor Owl, sharpish! Otherwise, you'll feel worse than a sailor without his grog!"

The cacophony of the square slowly died down as residents paused their activities, turning their attention to Popeye's impassioned plea. Whispers of "Did you hear that?" and "Maybe that's what I have!" rippled through the crowd as they began to share the crucial information. Gently, Popeye and Olive Oyl helped Little Squirrel to his feet. A tiny, grateful smile finally touched his pale face. Professor Owl, ever thoughtful, offered him a glass of warm water. "Don't you worry, my dear," he soothed, "now that you're listening to your body, and we're here to help, you'll be on the mend in no time."

The warm sun, as if approvingly, bathed the scene in a golden glow. Popeye, clutching his spinach can as a symbol of renewed strength, declared with a wide, resolute grin, "That's it! From this day forward, we're all going to be 'body detectives'! We'll sniff out those warning signals, protect ourselves, and look out for our pals!" Olive Oyl and Little Squirrel nodded with a fierce determination that mirrored his own. Soon, the square's cheerful bustle resumed, but it was a bustle with a newfound awareness. For every resident, the vital "warning signs" were now etched into their memories, never to be dismissed again.