4 January 2023

Photographing nudibranchs and the many other astonishing creatures of the ocean is an element of my ongoing multi-species fieldwork in Raja Ampat. In eleven segments below, I showcase the amazing, queer, and diverse world of nudibranchs and their companion species based on photos taken while doing underwater fieldwork.

#1

This is an  inornate headshield slug (Mariaglaja inornata). Until recently, it was classified in the genus Chelidonura. But molecular phylogenetic data in 2017 revealed that it belonged to a new genus, named Mariaglaja after the mother of one of the scientists. 

This is a good example of the ongoing rush of scientific discovery of new species and genera of nudibranchs.  Over 3,000 species of nudibranchs are known and described in the scientific literature, but new species are added to this catalogue all the time.  In fact, there might be twice as many species out there!  Western dive tourists love nudibranchs for their colorful photogenicity, and dive tourist interest is a key driver in these new discoveries.  In Beser, one of the several local languages in Raja Ampat, all nudibranchs are called taráir. And unless they happen to be one of the now many expert local dive guides, the Beser-speaking people of Raja Ampat that I know do not care much about nudibranchs.  In fact, they find dive tourists’ interest in nudibranchs either puzzling or vaguely suspicious. What does this interest really hide, they ask themselves (and me).  Local, touristic, and scientific interest in biodiversity rarely line up neatly!

#decolonizetheocean

 

#2

This is a Flabelina exoptata, I think, one of many species of aeolid nudibranchs.  The cerata on its back are used to breathe but also as defence.  They contain poisonous nematocysts that the nudibranch has acquired from its prey called hydroids, larvae of Hydrozoas, small stinging animals related to jellyfish.

#chemicalocean

 

#3

The dotted nudibranch (Jorunna funebris) feeds only on barrel sponges (Xestospongia sp), accumulating its toxins in the bronchial plume as a defence against predators.

#symbioticocean

 

#4

A Phyllida varicose, I think. Juveniles of Graeffe's sea cucumber (Pearsonothuria graeffei) are brightly colored blue and yellow to mimic this nudibranch and trick predators into avoiding it because this nudibranch like all others are toxic to fish and invertebrates.

#mimicryocean

 

#5

One of many still unnamed nudibranch species of the genus Tenellia.  This species is, I believe, just called Tenellia sp. 50.

#unknownocean

 

#6

Phyllidiella pustulosa. This is one of the most common nudibranchs and one of the first to be described by Western scientists in the early 1800s.

#studytheocean

 

#7

Philinopsis gardineri...another widespread species in the Indo-Pacific

#diverseocean

 

#8

A slightly blurry image of a Chromodoris annae. Notice the yellow branchial plume on the back. This plume is the reason for the name nudibranch which literally means “naked gills”.  The Chromodoris breathes through the plume which also holds high concentrations of a toxin called Latrunculin A. The nudibranch accumulates the toxin, which is poisonous to fish, from the sponges on which it feeds. Latrunculin A is currently being studied as a potential drug in the treatment of cancer.

#cleverocean

 

#9

A Doriprismatica atromarginata with black rhinosphore (sensory organs) and branchial plume on the back. Dorid nudibranchs like this one are named after Doris, the Greek goddess of the sea, who is associated with the abundance and fertility of the ocean.

#nudibranchocean

I discuss this species and the colonial trajectories of interest in nudibranchs in the chapter entitled: “Tidalectic Ethnography. Snorkeling the Coral Reefs of the Anthropocene”, a chapter in the anthology Rubber Boots Methods for the Anthropocene.  Curiosity, Collaboration and Critical Observation in Multispecies Fieldwork.

 

#10

Well, this is not a nudibranch… but cute and amazing nevertheless.  It is, I think,  a Persian Carpet Flatworm (Pseudobiceros bedfordi). After I took this photo, the flatworm suddenly lifted off from the sea floor and began swimming through the water like a belly-dancer or indeed like a magical carpet. Polyclad flatworms are, like many nudibranchs, hermaphrodites. And like nudibranchs, flatworms engage in what is called “penis fencing” during mating. Each hermaphroditic individual attempts to inject sperm into its opponent/partner in order to fertilize it! But flatworms are special in that they have two penises. Since they have no female genitals, they will inject the sperm into any part of the body of its opponent. The sperm will course through the body until it reaches the ovaries.  

#queerocean!

 

#11

This may look like seaweed, but it is a close-up of the head of the well-camouflaged blunt-end sea hare (Dorabella auricularia). Notice the two rolled rhinophores, chemical sensory organs, on its head, hiding amongst the many skin ruffles. The blunt-end sea hare  is the largest species of sea hare and can grow up to 50 cm. It has the ability to eject a purple ink if disturbed. The purple ink is secreted from the red algae on which the sea hares feed, but it is unknown what ecological or evolutionary function, if any, the purple ink has. It is probably not poisonous and unlike the octopus or cuttlefish who can make a quick escape while confusing a predator with its ink cloud, sea hares move too slowly to make an escape in any kind of a hurry. The Beser-speaking population of Raja Ampat call the sea hare “ronanék”.

#amazingocean