Nudibranchs - Sunshine Coast etc. / 8245b
All photos Copyright ©2003-2024 Gary Cobb and contributing photographers
Gary Cobb 0416 048 100
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Onchidium daemelli (Pulmonate)
Location: Eudlo Creek, Maroochydore, Queensland Australia
Size: 10-70 mm
Depth: Intertidal
Temperature: 25 C
Class: Gastropoda
Family: Onchidiidae
Photographs by Gary Cobb - Copyright 2003-2024

Onchidium is a pulmonate not a nudibranch, shell-less slug-like marine molluscs which live intertidally.
They range in size from 10-70mm long. They are usually oval in shape with a hard leathery mantle which ranges from smooth in some species to tuberculate in others. Some species have gill-like papillae scattered over the back and in other species there are eye-like sensory structures on the back. These relatives of the land snails have a section of the mantle cavity modified as a lung to breath air. It opens through a pore alongside the posteriorly opening anus, below the mantle (see below photo A). It crawls using muscular waves of the foot (from rear to the front) like land snails and slugs, whereas heterobranchs crawl with cilia and mucous so there are no waves of contraction(see below photo B).

photo A - Breathing pore

photo B - Muscular waves of the foot for crawling


Ventral view