Fluttershy's Animal Classes

by Majestical4729

Fish

At the sanctuary's streams, Fluttershy and Discord were meeting the fishes.

"Alright Discord, there are the fishes of he sanctuary's water bodies." Fluttershy told him, "Do you observe anything they all have in common?"

"Well...so far they all have eyes, mouths, nostrils...fins and tails." Discord noted, looking through the magnifying glass he summoned with his magic, "And scales on their body."

"There's a lot more than that, Discord. Although there are many characteristics that makes an animal a fish, there are only a few that all fishes known currently have, as the other characteristics have some exceptions." Fluttershy stated.

"Then let's go through the no exceptions characteristics, shall we? This is lesson number one after all." Discord pointed out.

"Of course," Fluttershy began, "All fishes are cold-blooded, which is also calledectothermic. This means that fish are unable to regulate their body temperature, relying solely on the outside environment for temperature regulation. The body temperature of fish changes as the environment's temperature changes."

"Fish are cold-blooded...so they r temperature changes..." Discord mumbled to himself as he noted down what Fluttershy just said, before exclaiming, "Oh! Just like amphibians!"

Fluttershy nodded, "Many fish species are extremely sensitive to these temperature changes and are only able to exist in a specific water temperature. Other species are able to survive in wider temperature ranges."

"I'm guessing that an animal caregiver has got to know that..." Discord said his thoughts out loud, getting another response from Fluttershy.

"Yes, indeed. Especially when they have to care for all kinds of animals. Speaking of animals, back to the lecture. Another characteristic all fishes share is gills. One of the basic criteria for an animal to be classified as a fish is the presence of gills throughout its life cycle. Gills are a necessity for underwater life: gills allow fish to absorb oxygen from water and release carbon dioxide, which allows them to “breathe” underwater. As with living in water, all fish have gills but not everything that has gills is a fish. Fish have gills throughout their lifespan while other species that have gills often lose them at some point. Tadpoles, for example, have gills, but eventually lose them as they metamorphose into frogs."

"So fishes get to keep their gills while amphibians do not." Discord wrote down in his notebook.

"Just remember that not all amphibians lose their gills, some gets to retain their gills," Fluttershy informed.

"Anything else?" Discord asked.

"All fish have gills, but some species of fish living in extremely oxygen-depleted environments have developed lungs as well." Fluttershy explained, "But we are not going to go deeper this lesson."

"So we are going to learn about that, some other time?" Discord asked.

"Yes, we are." Fluttershy nodded, before resuming her lecture, "Another characteristic that all fishes have, is fins. Fins are an almost universal characteristic of fish. Many types of fins exist, but the most common are the tail fin, a matching pair of side fins, dorsal fins, and an anal fin."

"So many fins! How am I going to remember them all?!" Discord complained.

"You'll get it dow, Discord. Just like you go everything down so far." Fluttershy assured, "Now, back to the lecture. The general purpose of fins is to provide motion, maneuverability, and stability. Pelvic and pectoral fins allow the fish to maneuver and maintain its stability while dorsal and ventral fins reduce the rolling motion while the fish is swimming and aids the fish during turns. The tail fin propels the fish forward while swimming."

"Fins help the fish control their direction?" Discord asked.

"In a way you can say yes they do," Fluttershy answered, "That being said, there are no set shapes, sizes, or even specific purposes for a particular kind of fin. Fin use and purpose varies wildly depending on the adaptations and needs of each type of fish."

"So different fish, different fins, different purposes," Discord questioned.

"You got that right," Fluttershy replied, before going back to the lecture, "Another characteristic is a swim bladder. All fish have a swim bladder, which is a specialized organ filled with air that helps ensure fish maintains a stable buoyancy in the water, neither sinking or floating too much."

"Sounds like a swim bladder is the perfect thing that can help us spend a day on the sea on ur planned upcoming vacation, Fluttershy..." Discord could not help but think of the vacation he was looking forward to, until Fluttershy snapped him out of it.

"Discord, vacation some other time, the lecture is more important right now!"

"Oh...right..." Discord replied quickly.

"The presence of a swim bladder allows the fish to sleep without sinking to the bottom of its habitat. In some species of fish, air is swallowed and sent to the swim bladder. This adaptation also helps the fish to survive in waters that do not have adequate levels of oxygen." Fluttershy explained.

"That's a lot about the swim bladder," Discord commented, writing the notes down.

"That's all about the swim bladder you need to know now." Fluttershy told him, "Now w are moving onto the water habitat characteristic; all fish live in water. This may seem too obvious to be worth stating, but there are some fish that can spend significant amounts of time out of the water. Mudskippers, for instance eat and interact with each other on land, and often go underwater only to hide from predators. They do not have lungs but can breathe through their skin and keep their gills moist with water that they store internally."

"Do I need to memorise the mudskipper specialty?" Discord asked.

"Since the mudskipper is special and unique, I suggest you do memories it." Fluttershy answered.

"Fine." Discord responded.

"Something to note here though is that while all fish live in water, not everything that lives in water is a fish. Whales and dolphins, for example, are mammals. Turtles live in water, too, but they’re reptiles, not fish." Fluttershy noted.

"Don't worry, I got the idea of that thanks to the mammals and reptiles lectures coming before this lecture about fish!" Discord assured.

"Now onto a characteristic that not all fishes share. Are you ready to learn what it is?" Fluttershy asked.

"Sure are," Discord replied.

"That characteristic is the way fishes reproduce." Fluttershy explained, "For starters, fishes lay eggs, but not all fishes do that. Some of them give birth, like sharks and guppies do."

"So that means some fish lay eggs, others give birth." Discord summarised.

"Yes, it does." Fluttershy answered, "For fishes that lay eggs, their eggs are fertilised by the sperm cells that comes from the males, after the eggs are laid. In other words, fish reproduce through external fertilisation."

"Lke amphibians?" Discord asked.

"Lie amphibians," Fluttershy nodded, "To the point that not only they are both externally fertilised, the eggs are soft-shelled, not Har-shelled unlike birds and reptiles."

"Soft-shelled eggs, that should be easy to remember." Discord commented.

"The way fishes reproduce is the main characteristic that not all fishes share, as most fishes may lay eggs, more than 500 species of fish reproduce by giving birth. But don't worry, you don't need to memorise them. We got books about them." Fluttershy assured.

"What a relief!" Discord heaved a sigh of relief, knowing that he did not have to memorise over 500 species of fish.

"That's all for today's fish lecture. Now to see if you really listened." Fluttershy announced, before beginning to ask Discord questions.

"Question One, what do fishes have to help them breathe?"

"Gills. All fishes have gills. Gills allow fish to absorb oxygen from water and release carbon dioxide, which allows them breathe underwater. All fish have gills, but not everything that has gills is a fish. Fish have gills throughout their lifespan while other species that have gills often lose them at some point. Tadpoles, for example, have gills, but eventually lose them as they metamorphose into frogs."

"Question Two: What do fish have to prevent them from sinking too deep?"

"Swim bladder. All fish have a swim bladder, which is a specialized organ filled with air that helps ensure fish maintains a stable buoyancy in the water, neither sinking or floating too much. The presence of a swim bladder allows the fish to sleep without sinking to the bottom of its habitat."

"Question Three, the body temperature of fishes?"

"All fish are cold-blooded, they are unable to regulate their body temperature, relying solely on the outside environment for temperature regulation. The body temperature of fish changes as the environment's temperature changes."

"Question Four, what helps fishes move?"

"Fins. Fins provide motion, maneuverability, and stability. Pelvic and pectoral fins allow the fish to maneuver and maintain its stability while dorsal and ventral fins reduce the rolling motion while the fish is swimming and aids the fish during turns. The tail fin propels the fish forward while swimming."

"Question Five: Fish habitat?"

"Water habitat, bodies of water. All fish live in water, but not all animals that live in water are fish. Whales and dolphins are mammals, sea turtles are reptiles. Some fish that can spend significant amounts of time out of the water. Mudskippers, for instance eat and interact with each other on land, and often go underwater only to hide from predators. They do not have lungs but can breathe through their skin and keep their gills moist with water that they store internally."

"Question Six; how do fishes reproduce?"

"Many fishes lay eggs, while others give birth like guppies and sharks. Those that lay eggs, fertilise the eggs after the eggs are laid, meaning that they reproduce through external fertilisation. Fish eggs are not hard-shelled unlike birds and reptiles. Instead, like amphibians, fish eggs are soft-shelled."

"Congratulations, Discord. You remember everything!" Fluttershy hugged the draconneques, after he had passes the test with flying colours.

"Of course I remember everything, or I wouldn't be the all powerful Discord, would I?" Discord asked.

Fluttershy giggled, "Alright, all mighty powerful Discord, just 2 more lectures to go, and lesson number 1 will be complete."

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Author's Note:

Acknowledgements:

https://sciencing.com/5-characteristics-fish-common-12059701.html

https://animals.mom.com/mom-fish-babies-4969.html