These neotenous characteristics may serve as "social releasers" that trigger our caretaker impulses, according to Archer.

Unlike a metamorphosed salamander, a neotenous one retains external gills and a tail and body fin, lacks moveable eyelids, and of course is obligatorily aquatic.

Rather, the perennibranchs are distinguished mainly by their neotenous features, and their development is likely to show simplifications which are not necessarily primitive.