Hypselodoris whitei

Hypselodoris whitei

''Hypselodoris whitei'' is a colourful species of sea slug or dorid nudibranch, a marine gastropod mollusk in the family Chromodorididae.
White's Hypselodoris (Hypselodoris whitei) Madidir III, Lembeh.
Two of the nudis are mating. You can see their genital in blue. 
I have just learned the craziest thing about how nudis mate: they are both hermaphrodites and dispute to be the male. They have developed a strategy by which they let their penis stuck on the other nudi (they loose it and grow a new one later) to avoid loosing the opportunity to inject their own sperm. You can find this cool info in these links:
http://legacy.earlham.edu/~brickte/
https://www.nationalgeographic.com/science/phenomena/2013/02/12/sea-slug-amputates-its-disposable-penis-but-has-two-spares/ Geotagged,Hypselodoris whitei,Indonesia,Spring

Appearance

''Hypselodoris whitei'' has a yellow body with purple longitudinal lines, and a purple bordered mantle. The gills and rhinophores are bright orange tipped with white. It is very similar in appearance to ''Hypselodoris maridadilus'' but that species lacks the white-tipped rhinophores and gills.

This species can reach a total length of at least 40 mm and feeds on sponges.
White's Hypselodoris (Hypselodoris whitei) Madidir III, Lembeh.
It is the same bunch as in previous pic. Link to previous image to see them mating:
https://www.jungledragon.com/image/66402/whites_hypselodoris_hypselodoris_whitei.html

This time pay attention to the one in the center; it only has one rhinophore. Sometimes they retract them but it has also been noticed by diver's that nudis are sometimes simply missing one of the rhinophores. I have read that one reason is because of encounters with predators like crabs or shrimps which remove them with their pincers. On rarer cases it could be the result of mutations as well. Rhinophores are very important organs for the nudi so no wonder why they can retract them when threatened (at least some of the species can do).
More info on this important organ here:
http://www.seaslugforum.net/showall/rhinonud Hypselodoris whitei

Distribution

This nudibranch was described from Caramata Passage between Sumatra and Borneo. It is reported from the Tropical Western Pacific from Australia to Hawaii.

References:

Some text fragments are auto parsed from Wikipedia.

Taxonomy
KingdomAnimalia
DivisionMollusca
ClassGastropoda
OrderNudibranchia
FamilyChromodorididae
GenusHypselodoris
SpeciesH. whitei
Photographed in
Indonesia