Description

 This species has a flattened and slender shape with a length of up to 37 mm. Pale cream or fawn in colour, with superficial orange pigments on its back. There are 14-16 transverse rows of finger-like extensions (cerata) on either side of its back, ten of which are mobile & elongated. The tips of the cerata are white or pale in colour, particularly at the anterior end of the body, forming a white ruff around the body. Generally the cerata, rhinophores and oral tentacles are white or pale yellow, the colour increasing in density towards the tip. Oral tentacles are slightly longer than the rhinophores, which are smooth or slightly wrinkled but neither of which have lamella. The alimentary canal is visible, and its colour may vary depending on diet from pale green and pink to dark brown.Spawn forms a convoluted spiral thread containing 200-1200 large eggs. Development is direct, i.e. there is no larval stage. Aeolidiella alderi feeds on a variety of sea anemonies mainly Cereus pedunculatus, Diadumene cincta and Sagartia species (Picton & Morrow, 1994). The body of Aeolidiella alderi is more slender than Aeolidia papillosa (Thompson & Brown, 1984).