Planctosphaera pelagica

Planctosphaera pelagica is the only known representative of the Planctosphaeroidea next to the acorn worms ( Enteropneusta ) and the Flügelkiemern ( Pterobranchia ) the gill hole Animals ( Hemichrodata ) within the new mouths ( deuterostomes ). So far, only larvae of these animals to determine why an exact assignment is not possible.

Discovered was Planctosphaera pelagica the first time in 1910 at the Norwegian deep-sea expedition of the " Michael Sars ". The crew fished it from a depth of 270 meters small transparent and spherical organisms that were described in 1932 as larval forms. An assignment to a full-blown species could not be carried so far, but it is considered an acorn worm that lives in the deep sea. Thus the Planctosphaeroidea would be no separate taxon more, but are classified in the acorn worms.

The larvae are with a diameter of 10 to 27 mm are relatively large and are characterized by branched eyelashes bands. The nozzle box takes the animals approximately 2/3 of the surface of the gut is V-shaped.