#rotifera

My tabletop roleplaying setting, Mortasheen, will be available to purchase for a limited time beginning on Halloween, 2025. Until then, bonus supplementary monsters will be going up every day of October. DAY 01/31: BRAINSLARK

Click the link for Brainslark's extensive lore, concept/design notes, and gameplay stats constructed by @gutsygills, art and writing by me.

About Mortasheen's Halloween soft-release

The history of the Mortasheen project and game

(Sources - 1, 2, own work, 4)

Rotifera is a phylum of microscopic and near-microscopic animals, commonly called Wheel Animals or Wheel Animalcules. Many are an important part of freshwater zooplankton.

Rotifers are common in freshwater throughout the world, with a few marine species. They range from 50 micrometres to over 2 millimeters, though most are around 0.1 to 0.5 mm long. Boasting a large amount of diversity, some rotifers are free-swimming, others move by inchworming along the ground, some are sessile and live inside tubes of gelatin attached to the substrate, and some live in sessile or planktonic colonies (seen in gif below). Rotifers are great little recyclers, feeding on detritus, dead bacteria, algae, and protozoans, eating particles up to 10 micrometres in size. They are also prey for many animals, including copepods, fish, bryozoans, comb jellies, true jellies, starfish, and tardigrades. Their fossils have been found in Devonian and Permian fossil beds.

Rotifers are sexually dimorphic, with females always being larger than males, if males of the species even exist at all. Male rotifers’ main lot in life is reproduction: they do not usually have a functional digestive system, and many are already sexually fertile at birth. The female has one or two ovaries, and releases eggs through a cloaca. Male rotifers have a penis which they either insert into the female’s cloaca, or use to inject sperm straight through her skin. Most species hatch as miniature versions of the adult. Females grow rapidly, reaching their adult size within a few days, while many males do not grow at all. Their lifespan lasts from a few days to a few weeks.

This poll also includes the parasitic Acanthocephala (4th image), or “Thorny/Spiny-headed Worms” which was once considered to be a discrete phylum but have since been found to be highly modifed rotifers, so I am including them in this phylum. Acanthocephalans have complex life cycles, involving many hosts.

Propaganda under the cut:

Rotifera: Wheel Animals. Mostly freshwater with some saltwater species, and can live in the water column, within the sediment, or attached to hard surfaces. Some Rotifers even live within the thin layer of moisture covering mosses. Their most distinctive feature is their corona and tentacles, which, when feeding, look like a rotating wheel. Their bodies are entirely soft except for the small jaw-like structures in their throats that help them chew their food. As detritivores, they are important contributors to the nitrogen cycle and breaking down dead organic matter.

Tardigrade, Rotifera, Anguillula