Yggrina

Yggrina is a burrowing organism that spends most of its life tunneling through the sediment. They consume scraps of organic material sunken onto the sediment as well as the sediment itself. Pictured here a yggrina emerges from the sediment after being disturbed by something. [Creature design by Squiddum]

Basic Information

Anatomy

Due to the tunnelling lifestyle of yggrina, the eyes of each segment have diminished in size as due to atrophy. The mouth has developed sideways closing ‘jaws’. This is homologous to the mandibles of Ypresi: the muscles that extended into appendages in Ypresi had remained embedded around the mouth in Yggrina, allowing controlled opening and closing of the mouth. Hundreds of tiny chemoreceptor pores surround the mouth and the front of the head. Across all segments, the swimming limbs and gill fronds now align laterally to the body. The swimming limbs have become thinner as they are now primarily used to move along the sediment. The gill frond continuously beat back and forth to get a continuous stream of oxygen while aiding in burrowing. The last segment has lost its eyes and gill fronds entirely. The swimming appendages of the last segment face towards the posterior end.

Genetics and Reproduction

Yggrina are true hermaphrodites. When two individuals meet, they will twirl together while simultaneously releasing gametes. This occurs while both partners are underground. Fertilised eggs are left to develop and hatch in the sediment.

Ecology and Habitats

Yggrina lives on sandy seabeds, acting as a detritivore. They consume clumps of sediment and bits of organic matter. They tunnel just beneath the seabed to feed on the sediment, occasionally surfacing to feed on scraps of detritus if any are detected above.

Dietary Needs and Habits

The ‘jaw’ grabs and shovels clumps of sediment and detritus into the mouth, carving out a trench or tunnel in the process. The food is digested as it traverses the intestinal tract, passing through inorganic/indigestible material out the posterior end.

Additional Information

Geographic Origin and Distribution

Found in all shallow water, at all latitude except the polar regions. Can be found on continental shelves and slopes as deep as the bathypelagic zone.

Perception and Sensory Capabilities

The eyes are vestigial, only capable of distinguishing light from dark. They would only be useful for detecting whether the organism is currently buried. On the other hand, the chemoreceptors around the mouth are sensitive and finely tuned, able to guide towards areas rich in nutrients. This allows Yggrina to locate food/mate despite being virtually blind.

EXTINCT

Genetic Ancestor(s)