Dendrodoris nigra is an unmistakable velvet smooth, black bodied, dendrodorid nudibranch (Figure 1) (Willan and Cobb, 2006, Willan and Coleman, 1984). Dorid nudibranchs display visible gill structures often forming circles or rosettes on their posterior back around the anus (Figure 2). As a cryptobranch dorid, D.nigra has the ability to retract its finely branched 6-8 gill plume into a pit on the top of its body, so may or may not be present when inspecting the animal (Behrens et al., 2005, Brodie et al., 1997).  

Figure 2: D.nigra's gill plume. Original photo by  Elsie-Mary Felix

D.nigra’s body form is usually broad and elongate with rather thin undulating margins and is soft and slimy to touch (Willan and Coleman, 1984, Brodie et al., 1997, Willan and Cobb, 2006). The animal is often completely black but comes in a several colour forms. These include an entirely black body with white specking or a dull red submarginal band (Figure 3) (Willan and Cobb, 2006).

D.nigra is relatively large in size, in comparison to other nudibranchs usually measuring 30-50mm in adults but can reach a maximum size of 85mm (Willan and Coleman, 1984). It lays an orange spawn mass which gives rise to orange-red juveniles which turn black as they mature , usually around 15mm in length.

Dendrodoris nigra can also be identified by its club-like rhinophores which are black with a very small spot of white at the tip and can also be retracted into rhinophoral pockets (Figure 4) (Willan and Cobb, 2006, Brodie et al., 1997). D.nigra has an extremely small head and as a member of Dendrodoridae lacks a radula. Instead, it has a pore-like mouth with a long suctorial tube. D.nigra’s thin oral tentacles are inconspicuous due to their fusion with the under surface of the animal.