REP: The Monolingulates

The monolingulates are free-swimming relatives of the multilingulates. While the anatomy of the two subphyla differs significantly, the segmentation and anatomy of the filtering organs are very similar. Monolingulates swim backwards, trailing their sticky tongues behind them and the development of simple eyes on their hind bodies reflects this. Compared to multilingulates they possess only a rudimentary skeleton that has little function besides stabilisation. The tongue excretes a sticky slime that catches up all kinds of living and dead organic matter, which is transported by flagellated cells into the feeding furrows on the sides and from there to the ventrally located mouth at the base of the tongue. The two openings between the torso and the tail lead to both the reproductive organs as well as to the respiratory organs. Mating occurs seasonally, when monolingulates form large swarms during nights, releasing their gametes together.

Feathertongue: a member of a group of monolingulates with short tongues and elongate secondary tendrils. In contrary to the long-tongued species they are able to retract the tongues into their torso when necessary. They are usually found in warmer seas than the others.

Tableback: A member of armoured monolingulates which has an enlarged, plate-like skeleton. The fin-like extensions of the torso create additional lift when swimming to balance out the additional body density. Due to this trait, tablebacks are found only in shallow water, where they often rest on the ground when not feeding.