Yisserin Species in A To Zoo | World Anvil


Yisserins are large cetaceans from the vast oceans of Yllvir, a planet in District 3. These animals have been hunted for the past few hundred years by the native Yiruns, of which we have several zookeepers here at the A To Zoo.


Yisserins are the largest cetacean on their native planet. These animals reach six metres as adults with a robust but streamlined appearance, no distinguishable beak, and a large tail. Yisserins are typically a dark grey, with a range from white to black, and seldom brown.

Yisserins have a triangular dorsal fin that extends from their necks to their tail. They have two pairs of flippers, one just beyond their necks and one mid-body. Their eyes are positioned on the sides of their heads, giving them a view of their surroundings to hunt for prey and avoid predators.

In the wild, yisserins grow up to two metres due to extreme levels of hunting that means the porpoises never have enough time to grow any more. In captivity these animals grow up to six metres, so long as they receive a proper diet and can live up until old age of 40 to 50 years.

Welcome everyone, to our yisserin enclosure! These animals are an incredibly endangered species, and our rehabilitation programme attempts to repopulate the waters of their home planet, Yllvir.
— Cetaceans 3 Zookeeper


Yisserins are typically quite curious, however wild animals are incredibly shy and avoid any and all activity on the surface of the water. They form large pods and like to group together for protection, since there are many predators larger than them and a lone yisserin is an easy meal.

Yisserins have been recorded diving to extreme depths, the record currently at 513 metres below sea level. They can drop their heart rates to 1 - 2 beats per minute when diving and when they resurface their heart reaches about 50 beats a minute, their average. These animals inhabit the south of the Echvos Sea during winters when weather is too extreme for yiruns to go hunting, and they travel north in summers to their feeding grounds.


Diet & Hunting

Yisserins are for the most part filter feeders, and throughout the year they strain plankton through their baleen plates. During summers, yisserins will travel north to feeding grounds, as shoals of krillfish like to gather in the warm waters. These krillfish are slow swimmers and are easy prey for yisserins, and they cause feeding frenzies that attract countless other predatory species.

Yisserin by Mochi
Scientific Name
Phocomors Abyssus
Home Planet
Average Length
6 metres
Average Lifespan
7 years in the wild
40 - 50 years in captivity
Cetaceans 3
Scientific Classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Phocoenidae
Genus: Phocomors
Species: P. Abyssus

Conservation Status

Distribution & Habitat

The range of yisserins has drastically decreased in modern times. Once these animals could be found across the three oceans of the planet, but today they are limited to the Echvos Sea, on the northern coast of the continent of Neogelus.

Yisserins prefer open waters, however recently they have been spotted venturing into kelp forests to hide from predators and yiruns.


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Apr 26, 2023 10:50 by Dr Emily Vair-Turnbull

Aw, I hope the rehabilitation is successful. :(

Emy x   Etrea | Vazdimet
Apr 26, 2023 11:23 by Mochi

It will be, the A to Zoo is the best zoo ever >:)

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