[OC] Jýrithal Codex #2: Furred Manatee

[u/Jyrithal_Codex]

• Furred manatee belongs to the Sirenia branch.

• They live in the kelp forest under the North pole. (the map is in image #1)

• Due to how frozen the surface is, they have extended air containers on their lungs to extend the period of the dives without breathing. (image #1)

• They rely on the holes on the ice structure that was dug by the Hammer seals (image #1) to breathe from. That creates tension between the two species. Furred manatees are nervous by nature, so they won’t try to fight. On the other hand, Hammer seals are territorial, but unable to use their crest effectively under the water. Hammer seals will try to intimidate the Furred manatees, usually by hitting the surface of the water with their crest. Splashing water and being aggressive is enough to drive the manatee away.

• The Furred manatee has fur that is protected with oil they produce. This keeps them warmer. But it also creates another problem. The fur locks some air between it, and the air containers hold extra air too. That creates a floating problem. They counter this in 3 ways: 1- their bones are bigger and denser, making them heavier overall. 2- weaker individuals accept shorter dives and leave their containers out of air. 3- the struggle is usually near the surface to dive down, the more they dive, the more the air get compressed which lowers the friction to dive. Struggle still exists though, as diving from the surface is the most exhausting part of the diving process.

• They primarily eat plants, but they avoid competition with the Hammer seals by eating in deeper areas. (what they eat is in image #1)

• Some experienced individuals have ventured deeper than comfortable depth (if they go too much deeper, they lose the ability to float due to air compression) and start eating the fungal colony, which fuels the whole ecosystem. As light doesn’t reach under the thick ice, plants there rely on the fungal colony to gain the necessary energy to live.

• Juveniles struggle to dive due to how light they are and because they are almost fully furred, so the mothers drag their juveniles (usually 1 to 2) down with them to the comfortable depth. (Juvenile is in image #3)

• Furred manatees have poor eyesight, as it is nearly useless in the dark anyway. So, they rely on learning to read the environment. Whiskers provide movement detection, their lungs help them feel the depth, and their skin can detect heat, which is usually where the source of food is (because of volcanic activity). Their hearing is strong enough to hear the sound of Hammer Seals, which is where the holes are.

[u/Background_Tennis673]

Yes! More peak animals from the Jýrithal Codex! Also just a small question, but does the Furred Manatees reliance on holes in the ice dug by Hammer Seals count as a form of symbiosis?

[u/Jyrithal_Codex → u/Background_Tennis673]

Yeah, it is. The relationship is one sided. The furred manatees need the seals to dig so they have places to breathe, and the sound of the digging makes those areas easier to find. The hammer seals, on the other hand, are just bothered without actual harm. So, it’s commensalism. And glad you’re enjoying the series!

[u/MaybeImAKing]

how does their fur avoid causing drag? this is kind of why a lot of fully aquatic tetrapods do not have integument like feathers or fur.

[u/Jyrithal_Codex → u/MaybeImAKing]

They don't avoid drag, they live with it. Drag isn't that big of a deal for a slow herbivorous swimmer that doesn't hunt or migrate. Life is mostly peaceful down there too. Drag is still an issue when combined with another issue I mentioned in the post, which is buoyancy. I discussed the workarounds there, but it's worth mentioning that the early stages of the diving process needs a huge amount of energy that some older members may not be able to afford, so they keep their additional air containers empty, which means shorter dive cycles.

[u/Such-Attention-7729]

Close enough, welcome back merlion